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Disease Issues
How serious a problem is influenza in the U.S.?
Influenza is the most frequent cause of death from a vaccine-preventable disease in the United States. In a study of influenza seasons from 1976–1977 through 2006–2007, the estimated number of annual influenza-associated deaths from respiratory and circulatory causes ranged from a low of 3,349 (1985–1986 season) to a high of 48,614 (2003–2004 season), with an average of 23,607 influenza-associated deaths. In addition to fatalities, seasonal influenza is also responsible for more than 200,000 hospitalizations per year. Rates of infection from seasonal influenza are highest among children, but the risks for complications, hospitalizations, and deaths are higher among adults ages 65 years and older, children younger than 5 years, and people of any age who have medical conditions that place them at increased risk for complications from influenza.
A novel H1N1 virus was first detected in March 2009 and quickly spread to pandemic levels. In the U.S., it is estimated that approximately 43–89 million persons became ill with 2009 pandemic H1N1 from April 2009 to April 2010. The virus also resulted in significant hospitalizations and deaths among children, adults 19–65 years, obese persons, and pregnant and post-partum women. The pandemic virus has continued to circulate. It was the predominant virus isolated during the 2013–2014 season.
The 2015–2016 influenza season was moderately severe and peaked later than usual in March 2016. Although H3N2 viruses predominated early in the season, H1N1 viruses were the most common later in the season and were the predominant virus for the entire season. The highest rates of hospitalization were among persons ages 65 years and older (88 per 100,000) and 50-64 years (46 per 100,000). There were 85 laboratory-confirmed influenza-related pediatric deaths reported.
Where can I get information on influenza and its surveillance?
Information regarding influenza surveillance is available October through May from the CDC influenza website at www.cdc.gov/flu/weekly/fluactivitysurv.htm. In addition, periodic updates about influenza are published in the MMWR. State and local health departments should be consulted regarding availability of influenza vaccine, access to vaccination programs, information about state or local influenza activity, and for reporting influenza outbreaks and receiving advice regarding their control.
Vaccine Recommendations Back to top
Which influenza vaccines will be available during the 2016–17 influenza season?
Multiple manufacturers are producing influenza vaccine for the U.S. market for the 2016–17 season. Inactivated vaccines will be produced using egg-based, cell culture-based, and recombinant technologies. Some of the inactivated influenza vaccines will be quadrivalent (contain four strains of influenza virus) rather than trivalent (three strains). Live attenuated influenza vaccine (LAIV, FluMist, AstraZeneca) is expected to be available but is not recommended to be used during the 2016–17 season (see next question). A complete listing of influenza vaccine products is available from the Immunization Action Coalition (IAC) at www.immunize.org/catg.d/p4072.pdf.
Why did CDC’s Advisory Committee on Immunization Practices (ACIP) recommend that LAIV not be used during the 2016–17 season?
This recommendation was made because of evidence of low vaccine effectiveness among children 2 through 17 years of age against the H1N1 strain of influenza virus during the 2013–14 and 2015–16 seasons. The reason for this lack of effectiveness of LAIV is not known. Only inactivated or recombinant influenza vaccines should be used during the upcoming influenza season. Details about this recommendation are available on pages 14–17 of the 2016–17 ACIP influenza recommendations, available at www.cdc.gov/mmwr/volumes/65/rr/pdfs/rr6505.pdf.
With the ACIP recommendation to not use live attenuated influenza vaccine (LAIV, FluMist, AstraZeneca) during the 2016–2017 season will there be enough inactivated influenza vaccine (IIV) to meet the demand for the upcoming season?
Influenza vaccine manufacturers project that as many as 171 to 176 million doses of influenza vaccine will be available for the 2016–2017 season. LAIV accounts for up to 14 million of those doses (about 8% of the total supply). Based on manufacturer projections, health officials expect that supply of IIV for the 2016–2017 season should be sufficient to meet any increase in demand resulting from the ACIP recommendation, though providers may need to check more than one supplier or purchase a vaccine brand other than the one they normally select.
I know that LAIV is not recommended to be used this season. If a dose of LAIV is administered this season, is it a valid dose, or should we repeat it with IIV?
CDC has advised that the dose can be counted. It does not need to be repeated with IIV.
What are the differences between trivalent and quadrivalent influenza vaccines?
Influenza vaccine produced for the 2016–2017 season will be either trivalent (three components) or quadrivalent (4 components). Both types of vaccine contain two A viruses and one B virus: The components of the 2016–2017 vaccines are:
  A/California/7/2009 (H1N1)pdm09-like virus (same as 2015–2016)
A/Hong Kong/ 4801/2014 (H3N2)-like virus
B/Brisbane/60/2008–like virus (Victoria lineage)
The quadrivalent vaccine will contain these three viruses, plus a B/Phuket/3073/2013–like virus (Yamagata lineage) virus.
If quadrivalent vaccine includes one additional strain, why isn't it preferred for use over trivalent vaccines?
Even though both influenza B viruses are likely to cause disease during an influenza season, traditionally experts have to choose between the two very different B viruses to include with the two A viruses based on which type of B virus is expected to predominate. This can be difficult to predict. The quadrivalent vaccine includes both B viruses. However, while quadrivalent vaccines may eventually replace trivalent vaccines, during the coming season the quantity of quadrivalent vaccine may be limited. Consequently ACIP does not express a preference for use of one type of influenza vaccine over another type (that is, quadrivalent over trivalent) for those for whom more than one type of vaccine is indicated and available.
Is it acceptable to administer a dose of the quadrivalent influenza vaccine to a patient who has already received the trivalent vaccine? We’ve had a few patients request this.
No. ACIP does not recommend more than one dose of influenza vaccine in a season, except for certain children age 6 months through 8 years for whom two doses are recommended.
Who is recommended to get vaccinated against influenza?
ACIP recommends annual vaccination for all people ages 6 months and older who do not have a contraindication to the vaccine.
When should influenza vaccine be given?
You can begin administering vaccine as soon as it becomes available. Early vaccination of children younger than age 9 years who need 2 doses of vaccine can be helpful in assuring routine second doses are given before the influenza season begins.
We have noticed that ACIP recommends that we begin vaccinating with seasonal influenza vaccine in September or even earlier. Does protection from seasonal influenza vaccine decline or wane within 3 or 4 months of vaccination? Should I wait until later in the year to vaccinate my elderly or medically frail patients?
ACIP recommends that to avoid missed opportunities for vaccination, providers should offer vaccination during routine healthcare visits and hospitalizations as soon as it becomes available. Antibody to inactivated influenza vaccine declines in the months following vaccination. A study conducted during the 2011–12 influenza season (Euro Surveill 2013;18:20388) found a decline in vaccine effectiveness late in influenza season, primarily affecting persons age 65 years and older. While delaying vaccination might permit greater immunity later in the season, deferral could result in missed opportunities to vaccinate, as well as difficulties in vaccinating a large number of people within a more limited time period. Vaccination programs should balance maximizing the likelihood of persistence of vaccine-induced protection through the season with avoiding missed opportunities to vaccinate or vaccinating after influenza virus circulation begins. Revaccination later in the season of people who have already been fully vaccinated is not recommended.
How late in the season can I vaccinate my patients with influenza vaccine?
Peak influenza activity generally occurs in January or February. Providers should continue vaccinating patients throughout the influenza season, including into the spring months (for example, through May), as long as they have unexpired vaccine in stock and unvaccinated patients in their office.
Because influenza occurs in many areas of the world during April through September, vaccine should be given to travelers who missed vaccination in the preceding fall and winter. Another late season use of vaccine is for children younger than age 9 years who needed 2 doses of vaccine but failed to get their second dose. For each of these situations, vaccine can be given through the month of June since most injectable influenza vaccine has a June 30 expiration date.
Which travelers are recommended to be vaccinated?
Healthcare providers should vaccinate any person who failed to get vaccinated in the previous vaccination season and who wants to reduce their risk of acquiring influenza during their upcoming travel, particularly if they are at high risk for influenza-related complications. This includes persons who are traveling to the tropics, traveling with organized tourist groups at any time of year, or traveling to the Southern Hemisphere during April–September.
If a patient received a dose of influenza vaccine in June (for example, for international travel), how long should the patient wait before getting vaccinated with the next season's flu vaccine?
There should be a minimum of 4 weeks between the doses in such situations.
I have a 24-year-old patient who received influenza vaccine in Argentina on June 19, 2016. Does he need to get another influenza vaccine during the current U.S. influenza season?
Yes. The person should be revaccinated with the 2016–2017 U.S. vaccine, even though the strains in the U.S. vaccine are the same as the 2016 Southern hemisphere vaccine. Vaccination again with the current vaccine will help assure protection through the influenza season into next spring.
I have a patient who received inactivated influenza vaccine in Brazil in September 2016. Does he need to be revaccinated with the current U.S. formulation?
No. The southern hemisphere influenza vaccine formulation for 2016 contains the same viruses in both trivalent and quadrivalent vaccines as the northern hemisphere vaccine for the 2016–17 season.
If an unvaccinated patient who has just recovered from a laboratory confirmed case of influenza comes into our clinic, should we vaccinate him?
Yes. Influenza vaccine contains three or four influenza vaccine virus strains; two A viruses and one or two B viruses, which are prepared based on circulating viruses from the previous influenza season. Infection from one virus type does not confer immunity to other types and it would not be unusual to be exposed to more than one type during a typical influenza season, so a person who has recently had influenza will benefit from receipt of a vaccine that contains additional influenza virus strains.
How long does immunity from influenza vaccine last?
Protection from influenza vaccine is thought to persist for a year because of waning antibody and because of changes in the circulating influenza virus from year to year. Antibody persistence may be shorter for persons age 65 years and older.
Some of my patients refuse influenza vaccination because they insist they "got the flu" after receiving the injectable vaccine in the past. What can I tell them?
There are several reasons why this misconception persists:
Less than 1% of people who are vaccinated with the injectable vaccine develop flu-like symptoms, such as mild fever and muscle aches, after vaccination. These side effects are not the same as having influenza, but people confuse the symptoms.
Protective immunity doesn't develop until 1–2 weeks after vaccination. Some people who get vaccinated later in the season (December or later) may be infected with influenza virus shortly afterward. These late vaccinees develop influenza because they were exposed to someone with the virus before they became immune. It is not the result of the vaccination.
To many people "the flu" is any illness with fever and cold symptoms or gasstrointestinal symptoms. If they get any viral illness, they may blame it on the vaccine or think they got "the flu" despite being vaccinated. Influenza vaccine only protects against certain influenza viruses, not all viruses.
The influenza vaccine is not 100% effective, especially in older persons. For more information on this topic, go to: www.cdc.gov/flu/professionals/vaccination/effectivenessqa.htm
Is a Vaccine Information Statement (VIS) only recommended or is it mandatory when administering influenza vaccine?
The use of a VIS for influenza vaccine given to any child or adult is mandatory under the National Vaccine Injury Compensation Program. Two VISs are available, one for LAIV (although LAIV is not recommended to be used during the 2016–17 season) and one for IIV. Each can be found at www.immunize.org/vis along with many translations. Beginning in the 2015–16 influenza season, the influenza VIS was modified so that it does not need to be replaced each year. The 2015–16 VIS can be used during the 2016–17 season.
Are there recommendations for the prevention of institutional outbreaks of influenza?
The most important factor in preventing outbreaks is annual vaccination of all occupants of the facility, and all persons in the facility who share the same air as the high-risk occupants. Groups that should be targeted include physicians, nurses, and other personnel in hospitals and outpatient settings who have contact with high-risk patients in all age groups, and providers of home care to high-risk persons (for example, visiting nurses, volunteers).
We are trying to provide influenza vaccination to all eligible patients during their stay in our hospital. If a patient does not remember if he or she has already received the vaccine this season, should we go ahead and vaccinate?
If a patient or family member cannot remember if the patient received influenza vaccine this season and no record is available, proceed with administering influenza vaccine, even if it might mean an extra dose is given. When a patient reports that they HAVE received influenza vaccine but does not have written documentation, ACIP states that in the specific case of influenza (and pneumococcal polysaccharide) vaccination, patient self-report of being vaccinated should be accepted as evidence of vaccination.
Do statin medications (taken to lower blood lipid levels) affect the efficacy of influenza vaccine?
Two recent studies raise the possibility that statin medications may blunt the effectiveness of influenza vaccines in seniors. Experts caution that more research is needed to better understand the issue. Because of their benefit, seniors should not stop taking their statin without consultation with their healthcare provider. Influenza vaccine remains the best protection we have against influenza, and provides at least some protection in people who take statins, so patients should still receive an influenza vaccine to be protected. There is no change to the ACIP recommendation for influenza vaccine.
Live Attenuated Influenza Vaccine (LAIV) Issues Back to top
Note: Live attenuated influenza vaccine (LAIV; FluMist), is not recommended by CDC’s Advisory Committee on Immunization Practices for use in the U.S. during the 2016–17 influenza season. Because LAIV is a licensed vaccine that might be available and that some providers might elect to use, the following information regarding LAIV from previous seasons is provided for informational purposes.
For whom is LAIV approved?
LAIV is currently approved by the Food and Drug Administration for use only for healthy non-pregnant persons ages 2 through 49 years.
How is LAIV administered?
The vaccine dose (0.2 mL) comes inside a special sprayer device. A plastic clip on the plunger divides the dose into two equal parts. The patient is seated in an upright position with head tilted back. Half of the contents of the sprayer (0.1 mL) is sprayed into each nostril.
Can LAIV be administered to persons with minor acute illnesses, such as a mild upper respiratory infection (URI) with or without fever?
Yes, unless clinical judgment suggests nasal congestion is present that might impede delivery of the vaccine to the nasopharyngeal mucosa, in which case deferral of administration should be considered until the congestion resolves.
Can a woman who is breastfeeding receive LAIV?
Breastfeeding is not a contraindication for any routine vaccination including LAIV.
Can LAIV be given to contacts of immunosuppressed patients?
Like other live vaccines, LAIV should not be administered to immunosuppressed persons. ACIP has stated a preference for using inactivated influenza vaccine for household members, healthcare personnel, and others who have close contact with severely immunosuppressed individuals (for example, patients with hematopoietic stem cell transplants) during those periods in which the immunosuppressed person requires care in a protective environment because of the theoretical risk that the live attenuated vaccine virus could be transmitted to the severely immunosuppressed individual and cause disease. Healthcare personnel or other persons who have close contact with persons with lesser degrees of immunosuppression (for example, persons with diabetes, persons with asthma taking corticosteroids, or persons infected with human immunodeficiency virus) who are otherwise eligible for LAIV may receive it. No special precautions need to be taken by the vaccinated person.
How long after someone is vaccinated with LAIV must they stay away from a severely immunosuppressed person (a person who is in protective [reverse] isolation)?
Persons should avoid contact with any person who is severely immunosuppressed for at least 7 days after receiving LAIV. There are no restrictions on being in contact with any other patients.
Is LAIV contraindicated for adults with asthma?
Asthma is a precaution for LAIV in people 5 years of age and older.
Can we give LAIV to a person who is taking an influenza antiviral medication?
An antiviral drug active against influenza virus may reduce the effectiveness of LAIV. If a person is taking an influenza antiviral drug, you should not administer LAIV until 48 hours after the person took the last dose of the drug. If a person takes antiviral drugs within 2 weeks of getting the nasal-spray influenza vaccine, the person should be revaccinated. However, you can give inactivated influenza vaccine (IIV) to a person who is taking an influenza antiviral drug.
One of our young patients made it impossible to administer the second part of the LAIV dose. What should we do?
A half dose of LAIV (or any other vaccine) is a non-standard dose and should not be counted. If you were unable to give the second half of the vaccine at that same appointment, you will have to provide another full dose of influenza vaccine at another time. Alternatively, you can give inactivated influenza vaccine any time after this partial dose. If you want to give LAIV again, you should wait four weeks, as it is a live vaccine.
For Children Back to top
Which children should receive influenza vaccine?
ACIP recommends annual influenza vaccination for all children age 6 months and older who do not have a contraindication to the vaccine.
Which influenza vaccines can we give to children?
Among the injectable inactivated influenza vaccines (IIV), Fluzone (Sanofi Pasteur) and FluLaval (GlaxoSmithKline) are approved by the FDA for use in children ages 6 through 35 months. There are several injectable influenza vaccines that can be given to children age 3 years or older.
The nasal spray live attenuated influenza vaccine (LAIV, FluMist, AstraZeneca) is approved for healthy children age 2 years and older. However, both the ACIP and the American Academy of Pediatrics recommend that LAIV not be used during the 2016–17 influenza season. Information about all influenza vaccines available in the U.S. is available in IAC's handout titled "Influenza Vaccine Products for the 2016–2017 Influenza Season" at www.immunize.org/catg.d/p4072.pdf.
Please provide details about the use of FluLaval influenza vaccine in children younger than 3 years.
On November 18, 2016, the Food and Drug Administration approved an extension of the age range of quadrivalent FluLaval IIV to include children 6 through 35 months of age. FluLaval was previously approved for people 3 years of age and older. The approval of the extended age range for FluLaval was based on a study showing an equivalent ("non-inferior") response compared to children who received Fluzone pediatric formulation. The vaccine will be supplied for this indication in manufacturer-filled syringes and multi-dose vials. The dosage approved for children 6 through 35 months of age is 0.5 mL – the same dosage as for people 3 years of age and older.
ACIP has not yet issued a recommendation regarding the use of FluLaval in children 6 through 35 months of age. However, clinicians are free to use this and other vaccines in a manner consistent with their labeling.
We've heard that ACIP has recommended limited use of one of the influenza vaccine products for children. Is that true?
Yes. In addition to the recommendation not to use LAIV during the 2016-17 season, ACIP recommends limitations on using Afluria, which is manufactured by bioCSL for the U.S. market, among children. The company’s 2010 Southern Hemisphere influenza vaccine (Fluvax and Fluvax Junior) was associated with increased post-marketing reports of fever and febrile seizures in children predominantly younger than age 5 years as compared to previous years. For this reason, ACIP recommends that Afluria, which is licensed for use in people age 5 years and older, not be used in children younger than age 9 years. ACIP further recommends that Afluria may be administered to children ages 5 through 8 years who are at high risk for influenza complications if there is no other age-appropriate IIV available, after risks and benefits of using this vaccine in this age group have been discussed with the parent or guardian. The vaccine should not be given to children younger than age 5 years. For detailed information, see www.cdc.gov/mmwr/pdf/rr/rr6207.pdf, page 18.
Which children younger than age 9 years will need 2 doses of influenza vaccine in this influenza season?
Children age 6 months through 8 years should receive a second dose 4 weeks or more after the first dose if they 1) are receiving influenza vaccine for the first time, or 2) did not receive a total of at least two doses of trivalent or quadrivalent influenza vaccine before July 1, 2016, or 3) if the child’s vaccination history is unknown. The two doses need not have been received during the same season or consecutive seasons.
For more details about the ACIP recommendations for which children need two doses, see www.cdc.gov/mmwr/volumes/65/rr/pdfs/rr6505.pdf, page 28.
You can also find this information in IAC's handout titled "Guide for Determining the Number of Doses of Influenza Vaccine to Give to Children Ages 6 Months Through 8 Years;" it is available at www.immunize.org/catg.d/p3093.pdf.
When determining whether a child age 2 through 8 years needs one or two doses of influenza vaccine this season, can we count doses of LAIV administered in past years? We were not sure because LAIV is not recommended this year.
CDC advises that doses of LAIV administered in past seasons can be counted.
Can a child who needs 2 doses of influenza receive 1 dose of quadrivalent vaccine and 1 dose of trivalent vaccine?
Yes. You can give these two vaccines, as long as the 2 doses are appropriately spaced.
Can a child 6 through 35 months of age who needs 2 doses of influenza vaccine this season receive one each of Fluzone Pediatric and FluLaval vaccine?
Yes. Both Fluzone Pediatric (0.25 mL dose) and FluLaval (0.5 mL dose) are approved by the Food and Drug Administration for use in children 6 through 35 months of age.
Please give details about the use of FluLaval influenza vaccine in children younger than 3 years of age.
On November 18, 2016, the Food and Drug Administration approved an extension of the age range of quadrivalent FluLaval IIV to include children 6 through 35 months of age. FluLaval was previously approved for people 3 years of age and older. The approval of the extended age range for FluLaval was based on a study showing an equivalent (“non-inferior”) response compared to children who received Fluzone pediatric formulation. The vaccine will be supplied for this indication in manufacturer-filled syringes and multi-dose vials. The dosage approved for children 6 through 35 months of age is 0.5 mL – the same dosage as for people 3 years of age and older.
If a child receives influenza vaccine at age 34 or 35 months for the first time (0.25 mL dose) and then returns for the second dose at age 37 months, should we give another 0.25 mL dose or should we give the 0.5 mL dose that is indicated for ages 3 and older?
The child should always receive the dose appropriate for his or her age at the time of the clinic visit; at age 37 months that would be 0.5 mL.
Can a clinic vaccinate children younger than age 3 years with influenza vaccine taken from a multidose vial of Fluzone or FluLaval? The multi-dose vials contain thimerosal as a preservative.
Yes. Multidose vials of Fluzone and FluLaval contain a small amount of thimerosal to prevent bacterial and fungal growth in the vial. Thimerosal-containing vaccines are safe to use in children. No scientific evidence indicates that thimerosal in vaccines cause adverse events unless the patient has a severe allergy to thimerosal. However, a few states have enacted legislation that restricts the use of thimerosal-containing vaccines in children. To find out if your state has such restrictions, check with your state immunization program (see www.immunize.org/coordinators for phone numbers).
There is a debate within my clinical department about not allowing influenza vaccine to be given with DTaP and PCV13. Are there data that state these should not be given concomitantly?
A CDC study has shown a small increased risk for febrile seizures during the 24 hours after a child receives the inactivated influenza vaccine at the same time as the PCV13 vaccine or DTaP vaccine. However, the risk of febrile seizure with any combination of these vaccines is small and ACIP recommends giving these vaccines at the same visit if indicated. See www.cdc.gov/vaccinesafety/concerns/febrile-seizures.html for more information.
For Special Groups Back to top
Is influenza vaccine recommended for pregnant women?
Yes. It is especially important to vaccinate pregnant women because of their increased risk for influenza-related complications. An increased risk of severe influenza infection was also observed in postpartum women (those delivered within the previous 2 weeks) during the 2009–2010 H1N1 pandemic. Vaccination can occur in any trimester, including the first. Only inactivated vaccine should be given to pregnant women.
Why do we vaccinate pregnant women against influenza when it is not recommended to vaccinate infants younger than age 6 months?
ACIP has recommended vaccinating pregnant women with inactivated influenza vaccine since 1997. Pregnant women are at increased risk for complications, hospitalization, and even death from influenza because of the increased physiologic strain of pregnancy on their heart, lungs, and immune system. Vaccination can occur in any trimester, including the first.
Influenza vaccine is not recommended for children younger than age 6 months because it is not approved for this age group. In addition, there are data that indicate that vaccinated pregnant women pass maternal antibodies to the fetus in the last few weeks of pregnancy; this helps protect the young infant against influenza. Vaccinating pregnant women protects women, their unborn babies, and their babies after birth.
Does ACIP recommend one influenza product over another for pregnant women?
Pregnant women can receive any of the inactivated vaccines. They should not be given the live attenuated influenza vaccine.
Can thimerosal-containing vaccine be given to pregnant women?
Yes, unless you live in a state that has enacted legislation restricting use in pregnant women. There is no scientific evidence that thimerosal in vaccines, including influenza vaccines, is a cause of adverse events, unless the patient has a systemic allergy to thimerosal.
I have a patient who is now 12 weeks pregnant. In September 2016, she received quadrivalent inactivated influenza vaccination (before she was pregnant). Should we give her another dose of 2016–17 influenza vaccine since she was not pregnant at the time of her first dose?
The Advisory Committee on Immunization Practices (ACIP) does not recommend more than one dose of influenza vaccine per season, except for certain children being vaccinated for the first time. The 2017–18 influenza vaccine may be available near the end of her pregnancy so she can be given a dose of next year's formulation at that time.
A co-worker of mine says we are supposed to give infants preservative-free influenza vaccine. Is this true?
No. CDC and ACIP express no preference for preservative-free vaccine for infants or any other group of vaccine recipients.
No scientific evidence exists that thimerosal in vaccines, including influenza vaccines, is a cause of adverse events, unless the patient has a systemic allergy to thimerosal. However, some states have enacted legislation that restricts the use of thimerosal-containing vaccines. Check with your state immunization manager to see if your state is one of them (www.immunize.org/coordinators).
Do diabetics who control their disease with diet need influenza vaccine?
People with a metabolic disease, including diabetes, should receive annual influenza vaccination with the inactivated vaccine.
Is influenza vaccine safe to administer to patients with multiple sclerosis?
Yes. Multiple sclerosis is not a contraindication to any vaccine, including influenza and pneumococcal vaccines.
Does influenza vaccine increase the HIV titer in the blood of people with HIV infection?
Although some studies have demonstrated a transient increase in replication of HIV following inactivated influenza vaccine, other studies have not found this. This temporary increase in HIV titer has not been associated with deterioration in either T-lymphocyte counts or clinical condition. ACIP believes that annual influenza vaccination with inactivated vaccine will benefit many HIV-infected persons.
Please tell me about Fluad, the new influenza vaccine for people age 65 years and older.
In November 2015, the Food and Drug Administration (FDA) licensed Fluad (Seqirus), a trivalent, MF59-adjuvanted inactivated influenza vaccine, for people age 65 years and older. Fluad is the first adjuvanted influenza vaccine marketed in the U.S. An adjuvant is a substance added to a vaccine to increase its immunogenicity. The MF59 adjuvant is based on squalene, an oil that occurs naturally in many plants and animals. Fluad has been used in Europe since 1997 and is approved in 38 other countries. In contrast to Fluzone High-Dose (Sanofi Pasteur), Fluad is a standard-dose vaccine, containing 15 mcg of hemagglutinin per dose.
A study published in 2014 found that the injectable vaccine Fluzone High-Dose (Sanofi Pasteur) protects people 65 years and older better than standard-dose Fluzone. Does ACIP preferentially recommend use of Fluzone High-Dose for all people age 65 years and older?
Aging decreases the body's ability to develop a good immune response after getting influenza vaccine, which places older people at greater risk of severe illness from influenza. A higher dose of antigen in the vaccine should give older people a better immune response and therefore provide better protection against influenza. However, despite published evidence of better protection from Fluzone High-Dose when compared to standard-dose Fluzone (N Engl J Med 2014; 371:635–45), ACIP has not stated a preference for this vaccine for people age 65 years and older.
May Fluzone High-Dose (Sanofi Pasteur) or Fluad (Seqirus) be administered to patients younger than age 65 years?
No. Fluzone High-Dose and Fluad are licensed only for people age 65 years and older and are not recommended for younger people.
Sometimes patients age 65 years and older who have received the standard-dose influenza vaccine hear about the high-dose (Fluzone High-Dose, Sanofi Pasteur) or adjuvanted vaccine (Fluad, Seqirus)  and want to receive that, too. Is this okay to administer?
No. ACIP does not recommend that anyone receive more than one dose of influenza vaccine in a season except for certain children age 6 months through 8 years for whom two doses are recommended.
Would giving an older patient 2 doses of standard-dose influenza vaccine be the same as administering the high-dose product?
No, and this is not recommended.
If a patient is undergoing treatment for cancer, is it safe to vaccinate her or him against influenza?
People with cancer need to be protected from influenza, and they can and should receive inactivated influenza vaccine (not LAIV) even if they are immunosuppressed. Cancer patients and survivors are at higher risk for complications from influenza, including hospitalization and death. Here is a helpful CDC web page on cancer and influenza for patients: www.cdc.gov/cancer/flu.
How soon after bone marrow transplant do we start to vaccinate our patients against influenza?
Inactivated influenza vaccine should be administered beginning at least 6 months after bone marrow transplant and annually thereafter for the life of the patient. A dose of inactivated influenza vaccine can be given as early as 4 months after transplant, but a second dose should be considered in this situation. A second dose is recommended routinely for all children receiving influenza vaccine for the first time.
A nursing home resident was admitted to the hospital with influenza and treated with oseltamivir. The person is now returned to the nursing home. The residents in the facility are being treated prophylactically with oseltamivir. Should the person who was hospitalized also receive oseltamivir prophylactically?
This is a complicated issue and the exact situation you describe is not addressed in the most recent ACIP recommendations on the use of influenza antiviral drugs. Whether to continue the antiviral drug depends on why the rest of the people in the facility are being treated. Oseltamivir for treatment of influenza is usually a 5-day course. If there is continued risk of exposure in the facility, it seems reasonable to continue the prophylactic treatment accordingly. The ACIP influenza antiviral guidelines are available at www.cdc.gov/mmwr/pdf/rr/rr6001.pdf.
For Health Care Personnel (HCP) Back to top
Why is influenza vaccination important for HCP? We already encourage them to stay home from work when they are sick.
Unfortunately, by the time an HCP has symptoms of influenza, they will have already exposed many patients since the virus is shed for 1-2 days before symptoms begin. Do the right thing. Start planning early to make sure all employees in your work setting receive annual influenza vaccination before the influenza season begins.
What are the ACIP recommendations for influenza vaccination of HCP?
Because HCP provide care to patients at high risk for complications of influenza, they should be considered a high-priority group for receiving vaccination. Achieving high rates of vaccination among HCP will protect staff and their patients, and reduce disease burden and healthcare costs. Vaccination rates of HCP are still too low; overall only 79% of HCP report influenza vaccination during the 2015–2016 season.
Influenza vaccination of HCP are summarized in the following points:
All HCP should be educated regarding the benefits of influenza vaccination.
Influenza vaccine should be administered annually to all eligible HCP.
A signed declination should be obtained from HCP who decline influenza vaccination.
Healthcare facilities should monitor HCP influenza vaccination coverage and declination at regular intervals.
HCP vaccination coverage should be used as one measure of a patient-safety quality program.
In 2011, ACIP published "Immunization of Health-Care Personnel," which includes information about all recommended vaccines (see www.cdc.gov/mmwr/pdf/rr/rr6007.pdf).
Which health care personnel should be vaccinated against influenza?
It is important to vaccinate ALL hospital and outpatient-care personnel, especially those that have direct contact with patients. In addition to physicians and nurses, vaccination in a hospital setting also includes full-time and part-time employees in radiology, laboratories, pharmacy, human resources, facilities management (housekeeping), food services, or laundry. Vaccinate volunteers as well. Others that should be vaccinated are emergency response workers, employees of nursing homes and assisted living programs, and providers of home care.
Which employees of chronic care facilities and nursing homes should be vaccinated against influenza?
All employees of long-term care facilities who have any patient contact and do not have a valid contraindication should receive annual influenza vaccination.
What is the Joint Commission's recommendation on vaccinating healthcare workers against influenza?
In January 2007, a new infection control standard of the Joint Commission became effective that requires accredited organizations to offer annual influenza vaccination to staff, volunteers, and licensed independent practitioners who have close patient contact.
I would like to help establish a policy of mandatory influenza vaccination for HCP in our facility and would like to learn from others. Can you help?
Every year more healthcare facilities are adopting mandatory vaccination policies for their employees. IAC has included many of these on its Honor Roll for Patient Safety, which gives special recognition to institutions that enforce mandatory vaccination for all personnel who are in the vicinity of a patient (for example, including volunteers, housekeeping staff). To read about the policies of the various facilities included in the Honor Roll, go to www.immunize.org/honor-roll/influenza-mandates/honorees.asp. We hope reviewing these policies will give you the information you need to assist in developing a policy for your facility.
We have a mandatory vaccination policy in our facility; however, we allow employees to choose not to be vaccinated after filling out and signing an informed declination form. What can we do to achieve assurances that patient safety is still maintained?
Though vaccination is the most effective means of protecting your patients from influenza, there may be instances where employees are not vaccinated for medical or personal reasons. In these instances, you may want to consider reassigning unvaccinated workers to non-patient areas or requiring that they wear masks throughout the influenza season.
I heard about a hospital where more than 95% of employees received influenza vaccine last year. How did they achieve such a high level of vaccination?
There are a number of hospitals that have implemented successful programs to vaccinate their healthcare workers. One example is the Virginia Mason Medical Center in Seattle, WA that has consistently achieved high levels of vaccination among their employees and volunteers. A report covering the first five years of their program was also published in the September 2010 issue of Infection Control and Hospital Epidemiology; an abstract of the report is available online at www.ncbi.nlm.nih.gov/pubmed/20653445.
IAC has developed an online Honor Roll for Patient Safety that recognizes hospitals, medical practices, professional organizations, and government entities that have taken a stand for patient safety by adopting policies endorsing mandatory influenza vaccination or by implementing mandatory influenza vaccination policies for all employees. To view the current listing of policies and position statements from leading organizations in medicine, pediatrics, pharmacy, public health, infectious diseases, and hospital administration, visit IAC's Influenza Vaccination Honor Roll at www.immunize.org/honor-roll/influenza-mandates.
Does the federal law that requires providing patients with VISs apply when administering influenza vaccine to employees and volunteers in hospitals or other workplaces?
If a vaccine is covered under the National Childhood Vaccine Injury Act—and almost all vaccines routinely administered to adults are (with the exception of PPSV and zoster)–it is mandatory under federal law to give the VIS for that vaccine to the vaccinee. Therefore, when you give influenza vaccine to employees and staff, you are required by law to provide them with a VIS.
Why does CDC recommend that we consider obtaining a signed declination from HCP who refuse influenza vaccination?
Some studies have shown an increase in HCP influenza vaccine acceptance when decliners are required to sign such a statement. In addition, such statements can help a vaccination program assess the reasons for declination and plan future educational efforts. IAC has posted the following suggested declination forms for healthcare workers:
Declination of Influenza Vaccination (English) found at www.immunize.org/catg.d/p4068.pdf
  Declination of Influenza Vaccination (Spanish) found at www.immunize.org/catg.d/p4068-01.pdf
Please tell me which professional associations have endorsed mandatory influenza vaccination for HCP and have created policy statements.
There are many professional associations that have issued policy statements supporting mandatory healthcare worker influenza vaccination. You can find information about these organizations as well as a list of more than 500 healthcare settings that have implemented mandatory vaccination programs on IAC's website at IAC's Influenza Vaccination Honor Roll web section at www.immunize.org/honor-roll/influenza-mandates/.
Contraindications and Precautions Back to top
For whom is inactivated influenza vaccine contraindicated?
Persons who have experienced a severe allergic reaction to a prior dose of influenza vaccine, or who are known to have a severe allergy to a vaccine component should not be vaccinated.
Precautions to vaccination include moderate or severe acute illness, and history of Guillain-Barré syndrome within 6 weeks of a dose of influenza vaccine.
What is the latest ACIP guidance on influenza vaccination and egg allergy?
ACIP revised its guidance on vaccination of persons with egg allergy for the 2016–17 season. ACIP recommends that people with a history of egg allergy who have experienced only hives after exposure to egg should receive any inactivated influenza vaccine without specific precautions (except a 15-minute observation period for syncope). People who report having had an anaphylactic reaction to egg (more severe than hives) may also receive any age-appropriate influenza vaccine. The vaccine for those individuals should be administered in a medical setting (such as a health department or physician office). Vaccine administration should be supervised by a healthcare provider who is able to recognize and manage severe allergic conditions. Although not specifically recommended by ACIP, providers may prefer an egg-free recombinant vaccine for people age 18 years and older with severe egg allergy.
A previous severe allergic reaction to influenza vaccine, regardless of the component suspected to be responsible for the reaction, is a contraindication to future receipt of the vaccine. For a complete list of vaccine components (i.e., excipients and culture media) used in the production of the vaccine, check the package insert (at www.immunize.org/fda) or go to www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/excipient-table-2.pdf.
For more details about giving influenza vaccine to people with a history of egg allergy, see www.cdc.gov/mmwr/volumes/65/rr/pdfs/rr6505.pdf, pages 29–30. You also may find the IAC handout “Influenza Vaccination of People with a History of Egg Allergy” helpful (see www.immunize.org/catg.d/p3094.pdf).
Is allergy to chicken or duck feathers a contraindication to receipt of an egg-based influenza vaccine?
The influenza VIS states that giving pneumococcal conjugate vaccine (PCV13) and inactivated influenza vaccine simultaneously may increase the risk of febrile seizures. Can we continue to give these two vaccines at the same time?
Yes, you can. Some, but not all studies, have reported increased rates of febrile seizures among children, especially those age 12 through 23 months, who received simultaneous vaccination with IIV and PCV13, when compared with children who received these vaccines separately. However, because of the risks associated with delaying either of these vaccines, ACIP does not recommend administering them at separate visits or deviating from the recommended vaccine schedule in any way.
Febrile seizures are not uncommon, occurring in 2% to 5% of all children; and they are generally benign. Healthcare providers should be prepared to discuss parents' questions about this issue, including questions about fever and febrile seizures.
The inactivated influenza vaccine VIS states: "Young children who get the flu shot and pneumococcal vaccine (PCV13) and/or DTaP vaccine at the same time might be slightly more likely to have a seizure caused by fever. Ask your doctor for more information. ACIP chose to include this statement on the VIS to inform parents of this potential risk.
For more information, see these CDC resources: www.cdc.gov/vaccinesafety/Concerns/FebrileSeizures.html and www.cdc.gov/vaccines/pubs/hcp/vis/vis-statements/flu-tiv-pcv-note.html.
We usually instruct our patients that they should separate vaccinations and allergy shots by at least 24 hours because if there were a reaction to one or the other, it wouldn't be possible to determine which was the cause. This becomes problematic during influenza vaccination season. What should we do?
The probability of a serious allergic reaction following any vaccine is extremely low if the person is properly screened. ACIP has not issued a recommendation that desensitization injections and vaccines be separated by any specific time period; consequently, we feel that you should take the opportunity to vaccinate.
When I was 5 years old, I had Guillain-Barrè syndrome (GBS) unrelated to vaccination. I am now 35 with no residual effects of the GBS. I am a nurse and my facility requires employees to receive influenza vaccine. Is it safe for me to be vaccinated?
Yes. A history of GBS unrelated to influenza vaccine is not a contraindication or precaution to influenza vaccination. GBS within 6 weeks following a previous dose of influenza vaccine is considered a precaution for use of influenza vaccines.
Administering Vaccines Back to top
Is there any plan to change the Influenza Vaccine Information Statement (VIS) for the 2017–2018 influenza season?
The current influenza vaccine VIS may be used for the 2017–2018 influenza season. No changes are planned.
Which formulations of influenza vaccines (i.e., nasal spray, intradermal, injectable high-dose, and injectable standard-dose) are licensed for various age groups?
There are multiple manufacturers of influenza vaccine and each may have differences in their product line (for example, licensed age group, mode of administration, etc.). IAC has developed a handout that summarizes each of the products available for the current influenza vaccination season that is available online at www.immunize.org/catg.d/p4072.pdf.
Does the ACIP prefer that healthcare professionals administer high-dose or adjuvanted influenza vaccine to people age 65 years and older, or is standard-dose influenza vaccine acceptable?
ACIP has no preference. CDC stresses that vaccination is the first and most important step in protecting against influenza.
The pneumococcal conjugate vaccine (PCV13, Prevnar, Pfizer) package insert says that in adults, antibody responses to PCV13 were diminished when given with inactivated influenza vaccine. Does this mean we should not give PCV13 and influenza vaccine at the same visit?
The available data have been interpreted that any changes in antibody response to either of the vaccines’ components were clinically insignificant. If PCV13 and influenza vaccine are both indicated and recommended they should be administered at the same visit. See the PCV13 ACIP recommendations at www.cdc.gov/mmwr/pdf/wk/mm6337.pdf, page 824.
We have had three employees who have tested positive for influenza by nasal swab within 2 weeks of receiving Fluarix Quadrivalent (GlaxoSmithKline) vaccine. Is there a time period after receiving influenza vaccine that a nasal swab can give a false positive result?
Inactivated influenza vaccines, including Fluarix, are not known to cause false positive nasal swab tests. However, false positive test results are possible with rapid tests, and these are more likely to occur when influenza prevalence in the area is low. For more information regarding interpretation of rapid influenza tests see www.cdc.gov/flu/professionals/diagnosis/rapidlab.htm.
What is the preferred anatomic site for administration of inactivated influenza vaccine (IIV)?
With the exception of intradermal vaccine (Fluzone Intradermal, Sanofi), IIV should be administered in the anterolateral thigh muscle of an infant or young child and in the deltoid muscle of an older child, adolescent, or adult. The anterolateral thigh muscle can also be used for an older child, adolescent, or adult if necessary. It is critical that intramuscular influenza vaccine be injected into a muscle. Influenza vaccination season is an opportune time to review proper intramuscular injection techniques with your staff. IAC has prepared a handout on how to administer intramuscular vaccine injections (available at www.immunize.org/catg.d/p2020.pdf) that can be used as a staff training tool.
Some of our patients believe that they have had reactions to influenza vaccine in the past, and request the dose to be split into 2 doses administered on different days. Is this an acceptable practice?
This is definitely not an acceptable practice. Doses of influenza vaccine (or any other vaccine) should never be split into “half doses”. If a “half dose” is given it should not be accepted as a valid dose and should be repeated as soon as possible with a full age-appropriate dose.
Should staff at drive-through influenza vaccination clinics encourage drivers to park and wait for 15 minutes after vaccination to make sure they don't have a syncopal (fainting) episode?
Yes. Syncope has been reported following vaccination. It is prudent for all persons to be observed for syncope for at least 15 minutes after vaccination.
Is it okay to draw up vaccine into syringes at the beginning of the day? If it isn't, how much in advance can this be done?
CDC discourages the practice of prefilling vaccine into syringes for several reasons, including
the increased possibility of administration and dosing errors,
  the increased risk of inappropriate storage,
  the probability of bacterial contamination since the syringe will not contain a bacteriostatic agent, and
the probability of reducing the vaccine's potency over time because of its interaction with the plastic syringe components.
Prefilling vaccine into syringes also violates basic medication administration guidelines, which state that an individual should administer only those medications he or she has prepared and drawn up.
Although pre-drawing vaccine is discouraged, a limited amount of vaccine may be pre-drawn in a mass-immunization clinic setting under the following conditions:
only a single type of vaccine (for example, influenza) is administered at the mass-immunization clinic setting,
  vaccine is not drawn up in advance of its arrival at the mass-vaccination clinic site,
  these pre-drawn syringes are stored at temperatures appropriate for the vaccine they hold,
no more than 1 vial or 10 doses (whichever is greater) is drawn into syringes, and
  clinic staff monitor patient flow carefully and avoid drawing up unnecessary doses or delaying administration of pre-drawn doses.
At the end of the clinic day, any remaining vaccine in syringes prefilled by staff should be discarded.
Sometimes I am unable to get 10 doses of influenza vaccine out of a 5.0 mL (10-dose) vial. Do you have any suggestions?
Certain vaccine syringes have small hubs where a volume of the vaccine that is withdrawn from the vial collects and is not available to be injected. Syringes without a hub are available; their use results in less vaccine wastage.
When removing both pediatric (0.25 mL) and adult (0.5 mL) doses from a multidose vial of Fluzone we can get more than 10 doses from the 5.0 ml vial. Can we continue to remove doses from the vial until it is empty?
No. Only the number of doses indicated in the manufacturer’s package insert should be withdrawn from the vial. For a 5.0 mL vial of Fluzone this is 10 doses. After the maximum number of doses has been withdrawn, the vial should be discarded, even if there is vaccine remaining in the vial and the expiration date has not been reached.
We inadvertently administered a 0.5 mL dose of Fluvirin (IIV3, Seqirus) to a 2-year-old child before realizing that the vaccine is only licensed for use in people age 3 years and older. Do we need to repeat the dose with an age-appropriate product?

No, the dose does not need to be repeated. However, this is a vaccine administration error as this formulation is not recommended for children younger than age 4 years. Clinicians should carefully select an influenza vaccine that is licensed for the age group of the person being vaccinated. At the time of this writing, Fluzone 0.25 mL (Sanofi Pasteur) is the only inactivated influenza vaccine approved for use in children age 6 months through 35 months.

If the child should need a second dose of influenza vaccine, an age-appropriate vaccine should be selected. IAC’s educational piece “Influenza Vaccine Products for the 2016–2017 Influenza Season” (available at www.immunize.org/catg.d/p4072.pdf) provides helpful information on the wide variety of influenza vaccines in use this season.
We inadvertently administered intradermal influenza vaccine (Fluzone ID, Sanofi Pasteur) to a patient who is not in the recommended age range of 18 through 64 years. What should we do now?
Because people younger than age 12 years or older than 65 years are more likely to have skin that is too thin for proper intradermal administration, a dose given to a person in these age ranges should be considered invalid, and the patient should be revaccinated. For people age 12 through 17 years, the dose is considered valid and does not have to be repeated if the clinician is certain that the dose was administered intradermally rather than subcutaneously. If there is any doubt about whether the dose was injected intradermally, it should be repeated.
If the recombinant influenza vaccine (FluBlok, Protein Sciences) was given inadvertently to a person younger than 18 years, can it be counted? Would there be any adverse side effects from this error?
Flublok is not licensed for persons younger than 18 years of age, so there are no data regarding safety and efficacy in this age group. However, no serious side effects would be expected. The dose does not need to be repeated. Even if no adverse reaction occurs, we request that vaccine administration errors like this be reported to the Vaccine Adverse Events Reporting System at www.vaers.hhs.gov.
A 2-year-old was inadvertently given a 0.25 mL dose of FluLaval rather than the recommended 0.5 mL dose. What should we do?
If the error is discovered while the child is still in the office you can administer the other "half" of the FluLaval dose. If the error is discovered later, then the child should be recalled to the office and given a full age-appropriate repeat dose, either a 0.5 ml dose of FluLaval or a 0.25 mL dose of Fluzone.
Storage and Handling Back to top
How should influenza vaccines be stored?
Both IIV and LAIV should be refrigerated at 2° to 8°C (36° to 46°F). Neither vaccine should be frozen.
This page was updated on August 23, 2017.
This page was reviewed on December 14, 2016.
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This website is supported in part by a cooperative agreement from the National Center for Immunization and Respiratory Diseases (Grant No. 6NH23IP22550) at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. The website content is the sole responsibility of IAC and does not necessarily represent the official views of CDC.