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H1N1 Influenza
General information Back to top
Can we test patients who think they already had H1N1 influenza to see if their infection was caused by H1N1?
There is no test readily available that can show whether a person had 2009 H1N1 influenza in the past. People for whom the 2009 H1N1 influenza vaccine is recommended should receive it, unless they can be certain they had 2009 H1N1 influenza based on a reverse transcriptase polymerase chain reaction (RT-PCR) test.
If a patient has received the seasonal influenza vaccine, do they need to receive the H1N1 influenza vaccine?
If a patient is in a risk group to receive H1N1 influenza vaccine, they should be vaccinated. Studies suggest that vaccination with seasonal influenza vaccine will not provide protection against the 2009 H1N1 influenza virus.
Should the 2009 H1N1 influenza vaccine be given to someone who had an influenza-like illness between April and now?
If an influenza-like illness (ILI) was confirmed as H1N1 by reverse transcriptase polymerase chain reaction (RT-PCR), then vaccination with H1N1 monovalent vaccine is not necessary for the 2009-2010 season. If the ILI was not confirmed by RT-PCR, then the person should be vaccinated if indicated. There is no harm in vaccinating a person who had 2009 H1N1 influenza in the past.
Vaccine development Back to top
What can I say to patients who think the H1N1 influenza vaccines are "new" or experimental?
The 2009 H1N1 influenza vaccines are being produced by the same companies using the same procedures used to produce seasonal influenza vaccines. The 2009 H1N1 vaccines are exactly the same as seasonal influenza vaccines except for the strain of influenza virus they contain. One way to approach this discussion is to emphasize that the 2009 H1N1 vaccine is not a "new" vaccine but rather is a change in the strains (just as is done in preparing new vaccine for each influenza season). Each year, experts look at the strains that are likely to be circulating during the next influenza season, and put those into the upcoming year's influenza vaccine. That's exactly what has been done in this case.
Most of the seasonal influenza vaccines distributed over the last decade have included H1N1-like strains. If the timing had been better, it is possible that the 2009 H1N1 strain could have been included in the 2009-2010 seasonal influenza vaccine.
Do any of the H1N1 influenza vaccines include an adjuvant?
None of the currently approved influenza A 2009 (H1N1) monovalent vaccines or seasonal influenza vaccines contains an adjuvant. (NOTE: An adjuvant is a substance that is sometimes added to the vaccine to enhance the immune response, so that smaller quantities of vaccine can be given.).

Do the H1N1 influenza vaccines use thimerosal as a preservative?
IAll multidose vials of influenza vaccine (both seasonal and H1N1) contain thimerosal as a preservative. There is no evidence that thimerosal is harmful. CDC recommends that pregnant women and children may receive influenza vaccine with or without thimerosal. However, because some pregnant women and parents are concerned about exposure to thimerosal, manufacturers are producing some preservative-free seasonal and 2009 H1N1 influenza vaccines in single-dose syringes.
The live intranasal H1N1 influenza vaccine is packaged in single doses so it does not use a preservative; however, it cannot be used for pregnant women or children younger than age 2 years.
Vaccination of targeted groups Back to top
Who is targeted to receive the H1N1 vaccine?
On Aug. 28, 2009, CDC issued recommendations for the use of the 2009 H1N1 influenza vaccine. The recommendations identify 5 initial target groups for H1N1 influenza vaccination. They are (1) pregnant women; (2) people who live with or provide care for infants younger than age 6 months (e.g., parents, siblings, day care providers); (3) healthcare and emergency medical services personnel; (4) children and young adults ages 6 months through 24 years; and (5) people ages 25 through 64 years who have medical conditions that put them at higher risk for influenza-related complications. You can access the complete recommendations at www.cdc.gov/mmwr/pdf/rr/rr58e0821.pdf.
According to ACIP, individuals aged 25-64 years with medical conditions that put them at higher risk for influenza-related complications should be among those targeted to receive the first available H1N1 influenza vaccine. What exactly are these high-risk conditions?
A footnote on page 5 of the ACIP recommendations for use of H1N1 influenza vaccine (www.cdc.gov/mmwr/PDF/rr/rr5810.pdf) defines these medical conditions in a footnote, as follows: "Chronic medical conditions that confer a higher risk for influenza-related complications include chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, cognitive, neurologic/neuromuscular, hematologic, or metabolic disorders (including diabetes mellitus) or immunosuppression (including immunosuppression caused by medications or by human immunodeficiency virus)."
Are healthcare personnel among the initial target groups for monovalent H1N1 vaccine?
Emphatically yes. Healthcare personnel are among the highest priority groups for both monovalent H1N1 AND seasonal influenza vaccine. HCP of all ages should be vaccinated as soon as the vaccines become available.
Why are pregnant women prioritized for vaccination?
Data from early 2009 H1N1 influenza cases in the United States show that pregnant women account for a disproportionate number of deaths, making them a high-priority group for vaccination (see www.thelancet.com/journals/lancet/article/PIIS0140-6736(09)61304-0/abstract). Also, guidance has been issued for clinicians to promptly treat pregnant women who become infected with the 2009 H1N1 virus with antiviral drugs (see www.cdc.gov/h1n1flu/clinician_pregnant.htm).
Why aren't adults age 65 years and older included as a priority group for the 2009 H1N1 vaccination as they are for seasonal influenza, where they are included as part of the age-50-and-older priority group?
Adults age 65 years and older are included as a priority group if they live with or care for infants younger than age 6 months or are a healthcare or emergency services provider. Current studies indicate that the risk of infection, hospitalization, and death from the 2009 H1N1 influenza virus among persons age 65 years and older is less than is the risk for younger age groups. Studies suggest that there is some degree of preexisting immunity to the 2009 H1N1 strains, especially among adults older than age 60 years. One possible explanation is that some adults in this age group have had previous exposure, either through infection or vaccination, to an influenza A (H1N1) virus.
Will H1N1 influenza vaccine be available for healthy people age 25 years and older (who are not in targeted groups)?
Once public health authorities at the local level determine that the H1N1 influenza vaccine demand for the 5 target groups has been met, providers will be notified that they can administer the vaccine to healthy people ages 25 through 64 years. Once demand for H1N1 influenza vaccine among younger age groups is met, vaccination should be expanded to all people age 65 and older.
Administering H1N1 vaccine Back to top
Will we be able to administer both the seasonal and H1N1 influenza vaccines at the same visit?
You can in most cases. See the points below.
You can administer both the inactivated seasonal and the inactivated H1N1 influenza vaccines at the same visit (using separate syringes and sites) or at any time before or after each other.
You can administer the inactivated seasonal and live H1N1 influenza vaccines together or at any time before or after each other.
You can administer the live seasonal and inactivated H1N1 influenza vaccines together or at any time before or after each other.
Administering both the live attenuated seasonal and the live attenuated H1N1 influenza vaccines at the same visit is NOT recommended because of concerns about competition between the 2 vaccine viruses. If you have only live vaccines for both seasonal and H1N1 influenza available, you should separate the doses of the live vaccines by at least 4 weeks.
In the package inserts, the age for two doses in children is different for seasonal (6 months through 8 years) and 2009 H1N1 monovalent vaccine (6 months through 9 years). Does CDC recommend that clinicians follow the recommendation in the package inserts?
Yes, CDC recommends that clinicians follow the guidance in the manufacturer package inserts. For 2009 H1N1 monovalent vaccines, that means that clinicians should administer two doses of 2009 H1N1 monovalent vaccine to children ages 6 months through 9 years. Persons 10 years and older should receive one dose.
If a child needs two doses of either seasonal or H1N1 influenza vaccine, can you give the child one dose of inactivated vaccine and one dose of live vaccine? This may be an issue because of supply fluctuation.
Once H1N1 influenza vaccine becomes available, should we stop administering seasonal influenza vaccine?
No. Providers should start administering seasonal influenza vaccine as soon as it is available and continue to administer it throughout influenza season, including during the winter and spring months.
Can 2009 H1N1 vaccine be administered at the same visit as other vaccines?
Inactivated 2009 H1N1 vaccine can be administered at the same visit as any other vaccine, including pneumococcal polysaccharide vaccine. Live (nasal-spray) 2009 H1N1 vaccine can be administered at the same visit as any other live or inactivated vaccine EXCEPT seasonal live attenuated influenza vaccine.
If seasonal LAIV and 2009 H1N1 LAIV are given during the same visit, do either or both doses need to be repeated, and if so, when?
There are no data on the administration of seasonal and 2009 H1N1 LAIV during the same visit. ACIP recommends that seasonal and 2009 H1N1 LAIV not be administered during the same visit. However, if both types of LAIV are inadvertently administered during the same visit, neither vaccine needs to be repeated.
What if seasonal or H1N1 LAIV is given 2 weeks after a dose of varicella vaccine or MMR? Does the dose of LAIV need to be repeated?
Yes. If two live virus vaccines are administered less than 4 weeks apart and not on the same day (EXCEPTION: live H1N1 and live seasonal influenza vaccines should not be given on the same day), the vaccine given second should be considered invalid and repeated. The repeat dose should be administered at least 4 weeks after the invalid dose. If the repeat dose is inactivated influenza vaccine it can be administered immediately.
What personal protective equipment is recommended for healthcare workers who are giving the 2009 H1N1 nasal-spray vaccine?
Personal protective equipment (gloves and masks) are not needed when administering nasal-spray vaccine, including the 2009 H1N1 nasal-spray vaccine.
Do providers working at a large-scale influenza vaccination event have to wash their hands between each patient?
Hands should be washed thoroughly with soap and water or cleansed with an alcohol-based waterless antiseptic between patients. The Department of Health and Human Services has provided the following guidance in its Pandemic Influenza Plan:
If hands are visibly soiled or contaminated with respiratory secretions, wash hands with soap (either non-antimicrobial or
antimicrobial) and water.
In the absence of visible soiling of hands, approved alcohol-based products for hand disinfection are preferred over antimicrobial soap and water or plain soap and water because of their superior microbiocidal activity, reduced drying of the skin, and convenience.
For more information, go to: www.cdc.gov/handhygiene
Though I know it is not necessary to wear gloves when providing injections, if a nurse chooses to wear gloves, should the nurse change gloves after administering each vaccination during a busy flu clinic?
Yes. Persons who administer vaccines should either wash their hands with soap and water, use alcohol-based hand sanitizer, or change their gloves between individual patient encounters.
Contraindications and precautions Back to top
Can patients on influenza antiviral prophylaxis (e.g., Tamiflu) receive seasonal and/or H1N1 influenza vaccine?
Such patients can receive inactivated seasonal or inactivated H1N1 influenza vaccine. A person taking an influenza antiviral drug (including Tamiflu or Relenza) should not be given the nasal-spray influenza vaccine until 48 hours after the last dose of the influenza antiviral medication was given. If LAIV is administered less than 48 hours after a dose of antiviral medication, or if antivirals are administered less than 2 weeks after LAIV is administered, then the LAIV dose should not be counted as valid.
Can a person with a runny nose receive nasal-spray influenza vaccine?
Can the live nasal-spray influenza vaccines be given to close contacts of pregnant women?
Yes. A pregnant woman can be in close contact with someone who has gotten the nasal-spray (live) vaccine for either H1N1 or seasonal influenza. A pregnant healthcare worker can also administer nasal-spray influenza vaccines to patients. Because the viruses in the nasal-spray vaccines are attenuated or weakened, vaccine viruses are unlikely to cause any illness symptoms, even if an unvaccinated person inadvertently gets vaccine viruses in their nose. The nasal-spray vaccine against seasonal influenza viruses has been used in millions of school children and healthy adults since it was licensed, and there have been no reports of pregnant women becoming ill after exposure to their vaccinated children or other family members.
Although the live nasal-spray influenza vaccines can be given to contacts of pregnant women, they should not be administered to pregnant women.
Are there any contraindications to giving breastfeeding mothers the 2009 H1N1 vaccine?
Breastfeeding mothers can get either live or inactivated H1N1 influenza vaccine. They can also receive either live or inactivated seasonal influenza vaccine. As noted elsewhere, seasonal and H1N1 live (nasal-spray) vaccines should not both be given at the same visit.
Can healthcare workers who cannot receive the nasal-spray vaccine (e.g., pregnant women, older adults, persons with chronic medical conditions) administer this vaccine to others?
Yes. Healthcare workers who cannot get the nasal-spray vaccine themselves can administer the vaccine to others.
Clinic materials Back to top
Can we use the same influenza VISs that have been issued from CDC for seasonal influenza vaccine when we give the 2009 H1N1 influenza vaccine?
No. You should use the separate VISs for the monovalent 2009 H1N1 vaccine only to the 2009 H1N1 vaccine. You will find them posted at www.immunize.org/vis.
Where can I find VISs for seasonal and H1N1 influenza vaccines?
IAC posts the English-language VISs developed by CDC and all available translations on its website as soon as they become available. Please note that all VIS translations are graciously donated, so IAC is unable to guarantee specific delivery dates.
To access all available seasonal inactivated influenza VISs, go to: www.immunize.org/vis/vis_flu_inactive.asp
To access all available seasonal live influenza VISs, go to: www.immunize.org/vis/vis_flu_live.asp
To access all available H1N1 inactivated influenza VISs, go to: www.immunize.org/vis/vis_h1n1_inactive.asp
To access all available H1N1 live influenza VISs, go to: www.immunize.org/vis/vis_h1n1_live.asp
What if our organization needs a VIS translation before it is available from IAC's website, or needs VISs in a language that is unlikely to be donated by others? Is it legal to translate CDC's English-language VIS ourselves?
Permission is not required to translate a VIS. However, providers should not change the text of a VIS or write their own VISs. It is permissible to add a practice's name, address, or phone number to an existing VIS.
If your organization decides to have some VISs translated, consider sharing the translations with IAC for possible posting to our website. You can access our guidelines for translations at www.immunize.org/printmaterials/print_translate.asp
Do you have any other resources that would make this difficult influenza season easier for those of us providing vaccines?
IAC has developed standing orders for both seasonal and H1N1 influenza vaccination and has revised its influenza screening questionnaires to be suitable for both seasonal and H1N1 influenza vaccines.
Standing Orders for Administering Seasonal Influenza Vaccines to Children & Adolescents
Standing Orders for Administering Seasonal Influenza Vaccine to Adults
Standing Orders for Administering Influenza A (H1N1) 2009 Monovalent Vaccines
Screening Questionnaire for Injectable Influenza Vaccination--the same form may be used to screen for both seasonal and H1N1 influenza vaccine
  English: www.immunize.org/catg.d/p4066.pdf
Spanish: www.immunize.org/catg.d/p4066-01.pdf
Screening Questionnaire for Intranasal Influenza Vaccination--the same form may be used to screen for both seasonal and H1N1 influenza vaccines
  English: www.immunize.org/catg.d/p4067.pdf
Spanish: www.immunize.org/catg.d/p4067-01.pdf
Reviewed on 11/09
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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. 5U38IP000290) 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.