Ask the Experts: Influenza

Results (96)

It is important to vaccinate all healthcare personnel, including paid and unpaid workers who may be exposed to patients or infectious materials. This includes direct patient care staff (e.g., physicians, nurses, and therapists), and staff and volunteers in pharmacy, radiology, laboratory, human resources, facilities management (housekeeping), food services, and laundry. Vaccination should include healthcare staff in all settings, such as hospitals, outpatient clinics, pharmacies, emergency response, nursing homes and assisted living facilities, and home care.

Last reviewed: September 10, 2023

All people working in long-term care facilities who do not have a valid contraindication should receive annual influenza vaccination.

Last reviewed: September 10, 2023

Since January 2007 the Joint Commission has required accredited organizations to offer annual influenza vaccination to staff, volunteers, and licensed independent practitioners who have close patient contact.

Last reviewed: September 10, 2023

Every year more healthcare facilities are adopting mandatory vaccination policies for their employees. Immunize.org has included more than 1,330 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 (including volunteers and 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. In addition, the National Adult and Influenza Immunization Summit (NAIIS) has developed tools to assist post-acute and long-term care facilities that plan to implement influenza vaccination requirements for HCP at www.izsummitpartners.org/naiis-workgroups/influenza-workgroup/tools-for-ltcf/. We hope reviewing these policies and tools will give you the information you need to assist in developing a policy for your facility.

Last reviewed: September 10, 2023

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.

Last reviewed: September 10, 2023

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.

Last reviewed: September 10, 2023

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. Immunize.org has posted the following suggested declination form for healthcare workers at www.immunize.org/catg.d/p4068.pdf.

Last reviewed: September 10, 2023

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 1,330 healthcare settings that have implemented mandatory vaccination programs on Immunize.org’s website at Immunize.org’s Influenza Vaccination Honor Roll web section at www.immunize.org/honor-roll/influenza-mandates/.

Last reviewed: September 10, 2023

Contraindications to egg-based inactivated influenza vaccines (IIV) are a severe allergic reaction to a prior dose of any influenza vaccine (any egg-based IIV, ccIIV, RIV, or LAIV of any valency) or a severe allergy to an influenza vaccine component (except egg). ACIP recommends that people with egg allergy of any severity may receive any influenza vaccine appropriate for their age and health status.

Precautions to egg-based IIV include moderate or severe acute illness, and history of Guillain-Barré syndrome within 6 weeks after a dose of influenza vaccine.

Contraindications to ccIIV4 are a history of a severe allergic reaction or any component of ccIIV4.

Precautions to ccIIV4 are moderate or severe acute illness, a history of Guillain-Barré syndrome within 6 weeks after a dose of influenza vaccine, and a history of a severe allergic reaction to a previous dose of any other influenza vaccine (e.g., any egg-based IIV, RIV, or LAIV).

Contraindications to RIV4 are a history of a severe allergic reaction or any component of RIV4.

Precautions to RIV4 are moderate or severe acute illness, a history of Guillain-Barré syndrome within 6 weeks after a dose of influenza vaccine, and a history of a severe allergic reaction to a previous dose of any other influenza vaccine (e.g., any egg-based IIV, ccIIV, or LAIV).

Last reviewed: September 10, 2023

A severe allergic reaction to any influenza vaccine is a contraindication to receiving additional doses of the same vaccine or receiving any egg-based influenza vaccines. The following table summarizes the contraindications and precautions for different types of influenza vaccine and is adapted from table 3 of the 2022–23 influenza ACIP recommendations at www.cdc.gov/mmwr/volumes/71/rr/pdfs/rr7101a1-H.pdf:

Vaccine (of any valency) associated with previous serious or anaphylactic reaction Available 2022–23 influenza vaccines
Egg-based IIV4s
and LAIV4		 Cell-culture- based IIV4: ccIIV4 (Flucelvax) Recombinant IIV4: RIV4 (Flublok)
Any egg-based IIV or LAIV Contraindication Precaution † Precaution †
Any ccIIV Contraindication Contraindication Precaution †
Any RIV Contraindication Precaution † Contraindication
Unknown influenza vaccine Allergist consultation recommended

† Note regarding patients having either of the above precautions for either ccIIV or IIV: use of ccIIV4 and RIV4 in such instances should occur in an inpatient or outpatient medical setting under the supervision of a healthcare provider (HCP) who can recognize and manage severe allergic reaction; HCPs can also consider consulting with an allergist to help identify the vaccine component responsible for the reaction.

Last reviewed: September 10, 2023

Contraindications are:
• a history of severe allergic reaction to a vaccine component (except egg) or after a previous dose of any influenza vaccine (people with egg allergy of any severity may receive LAIV if it is otherwise appropriate for their age and health status)
• concomitant aspirin or salicylate-containing therapy in children and adolescents because of the risk of Reye syndrome
• children age 2 through 4 years who have received a diagnosis of asthma or whose parents or caregivers report that a healthcare provider has told them during the preceding 12 months that their child had wheezing or asthma or whose medical record indicates a wheezing episode during the preceding 12 months
• immunosuppression due to any cause including medications or HIV infection
• cerebral spinal fluid (CSF) leak, cochlear implant, or anatomic asplenia or functional asplenia (e.g., due to sickle cell anemia)
• close contacts and caregivers of severely immunosuppressed people who require a protected environment (e.g., reverse isolation in a hospital)
• pregnancy
• receipt of influenza antiviral medication within the previous 48 hours (oseltamivir or zanamivir), previous 5 days (peramivir), or previous 17 days (baloxavir)

Precautions are:
• moderate or severe acute illness with or without fever (defer)
• history of Guillain-Barré syndrome within 6 weeks after a dose of influenza vaccine
• asthma in a person age 5 years or older
• underlying medical conditions that might predispose to complications after influenza virus infection, such as chronic pulmonary, cardiovascular (except isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders including diabetes mellitus

Last reviewed: September 10, 2023

The 2023 influenza ACIP recommendations state that everyone 6 months of age or older with egg allergy should receive an influenza vaccine. Any influenza vaccine (egg based or non-egg based) appropriate for the person’s age and health status can be used.

Egg allergy alone does not require any additional safety measures for influenza vaccination beyond those recommended for any recipient of any vaccine. All vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are available.

A person who has had a previous severe allergic reaction to an influenza vaccine has a contraindication to future receipt of that 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 (available at www.immunize.org/fda) or go to www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/excipient-table-2.pdf.

For more on the evidence and rationale supporting the change in recommendations regarding influenza vaccination and egg allergy, see pages 12 and 13 of the published ACIP recommendations for the 2023–24 season at www.cdc.gov/mmwr/volumes/72/rr/pdfs/rr7202a1-H.pdf.

Last reviewed: September 10, 2023

No.

Last reviewed: September 10, 2023

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 pneumococcal conjugate vaccine (PCV13, Pfizer) or DTaP vaccine (Daptacel, Infanrix, Pediarix, Pentacel), 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. The risk of febrile seizure following coadministration of influenza vaccine with the newer PCV15 or PCV20 pneumococcal conjugate vaccines has not been evaluated.

Febrile seizures may be triggered by any cause of fever and occur in up to 5% of all children, and they are generally benign. Healthcare providers should be prepared to answer parents’ questions about febrile seizures and fever when discussing vaccinations. Here is a CDC resource that addresses these concerns: www.cdc.gov/vaccinesafety/concerns/febrile-seizures.html.

Last reviewed: September 10, 2023

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.

Last reviewed: September 10, 2023

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.

Last reviewed: September 10, 2023

Both the inactivated and recombinant influenza vaccine VIS and the live influenza vaccine VIS were updated on August 6, 2021. These VISs and translations in multiple languages are available here: www.immunize.org/vis/.

Last reviewed: September 10, 2023

Immunize.org has a 1-page printable document that summarizes each of the products available for the current influenza vaccination season, including age indications, at www.immunize.org/catg.d/p4072.pdf.

Last reviewed: September 10, 2023

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 temperature
  • The probability of bacterial contamination
  • The probability of reducing the vaccine’s potency over time

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
  • 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, all remaining vaccine in syringes prefilled by staff should be discarded.

Last reviewed: September 10, 2023

Vaccinating people against influenza who have recently tested positive for COVID-19 involves multiple considerations, such as whether vaccinating them could expose others to COVID-19, how sick they are, their risk for severe influenza illness, the ability to vaccinate at a later date, and the desire to avoid confusing postvaccination symptoms with those of COVID-19. Usually, people who are infectious should not be brought to a vaccination setting if doing so could expose others to COVID-19. Any moderate or severe acute illness is a precaution to influenza vaccination: vaccination should generally be deferred until recovery. For people with mild or asymptomatic COVID-19, delaying vaccination might be considered to avoid confusing COVID-19 symptoms with postvaccination reactions.

CDC may continue to modify recommendations for vaccination of this population.

Last reviewed: September 10, 2023

Inactivated influenza vaccines are not known to cause false positive nasal swab tests. The results may indicate real infections; however, false positive test results are possible with rapid tests, and these are more likely to occur if the tests are done 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.

Last reviewed: September 10, 2023

IIV should be administered in the anterolateral thigh muscle of an infant or young child. IIV and RIV (approved for people age 18 years and older) should be administered 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. Immunize.org has prepared a printable document 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.

Last reviewed: September 10, 2023

This is not an acceptable practice. Doses of influenza vaccine (or any other vaccine) should never be split into “half doses.” If a “half dose” is administered, it should not be accepted as a valid dose. The second half of the dose may be administered if the error is caught and corrected at that visit; if not, repeat the vaccination as soon as possible with a full age-appropriate dose.

Last reviewed: September 10, 2023

Yes. Syncope may occur following any vaccination. It is prudent for all people to be observed for syncope for at least 15 minutes after any vaccination.

Last reviewed: September 10, 2023

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.

Last reviewed: September 10, 2023

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 Quadrivalent this is 10 doses. For Afluria Quadrivalent 5.0 mL multi-dose vial, the package insert states that the stopper can be punctured up to 20 times, allowing up to 20 doses of 0.25 mL dose for children age 6–35 months old. After the maximum number of doses has been withdrawn or number of punctures of the stopper has met the FDA-recommended limit, the vial should be discarded, even if there is vaccine remaining in the vial and the expiration date has not been reached.

Last reviewed: September 10, 2023

The dose does not need to be repeated. However, this is a vaccine administration error. Clinicians should carefully select an influenza vaccine and vaccine dose that is licensed for the age group of the person being vaccinated. The error should be conveyed to the child’s parent or guardian and also reported to Vaccine Adverse Events Reporting System (VAERS) at www.vaers.hhs.gov. Actions should be taken to limit vaccine administration errors at the clinic where the error occurred. Immunize.org’s educational piece “Influenza Vaccine Products for the 2023-24 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.

Last reviewed: September 10, 2023

RIV4 is not licensed for people 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, vaccine administration errors like this should be reported to the Vaccine Adverse Events Reporting System (VAERS) at www.vaers.hhs.gov.

Last reviewed: September 10, 2023

If the error is discovered on the same clinic day you can administer the other “half” of the FluLaval Quadrivalent dose. If the error is discovered the next day or later, the dose should not be counted. The child should be recalled to the office as soon as possible and given a full age-appropriate repeat dose, either a 0.5 mL dose of FluLaval Quadrivalent, a 0.5 mL dose of Fluarix Quadrivalent, a 0.25 or 0.5 mL dose of Fluzone Quadrivalent, a 0.25 mL dose of Afluria Quadrivalent, or a 0.5 mL dose of Flucelvax Quadrivalent.

Last reviewed: September 10, 2023

All influenza vaccines (inactivated, recombinant, and live attenuated vaccines) should be stored at refrigerator temperature of 2° through 8°C (36° through 46°F). No influenza vaccine should be frozen. Influenza vaccine exposed to freezing temperature should not be used.

Last reviewed: September 10, 2023

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