Influenza (Flu) Vaccine Safety

Key points

  • Influenza (flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. Serious complications of flu infection can result in hospitalization or death.
  • There are vaccines that can help reduce the risk from flu and its potentially serious complications.

Overview

Influenza (flu) can cause mild to severe illness, and its complications can result in hospitalization or death. Some people, such as older people, young children, and people with certain health conditions, are at higher risk for developing serious flu complications.

CDC recommends annual influenza vaccination for everyone 6 months and older with any flu vaccine licensed by the FDA that is appropriate for the recipient’s age and health status.

Available vaccines & manufacturer package inserts

Types of flu vaccines

Injectables (inactivated influenza vaccines (IIV) and recombinant influenza vaccines (RIV))

  • Do not contain live flu viruses.
  • Come in various types of trivalent, quadrivalent, high-dose, adjuvanted, cell-based, and recombinant formulations.
Keep Reading: Vaccine Information Statement: Inactivated or Recombinant Shot

Nasal spray (live, attenuated influenza vaccine (LAIV)

  • Contains live flu viruses that are attenuated (weakened), so that they will not cause influenza.
Keep Reading: Vaccine Information Statement: Live, Intranasal Spray

Available flu vaccines & manufacturer package inserts

Keep in mind‎

There is no preferential recommendation for any one flu vaccine over another. The composition of U.S. flu vaccines is reviewed annually and updated as needed to match circulating flu viruses. In any given flu season, there are multiple FDA-licensed flu vaccines from different manufacturers available for use.

For children and adults

  • The FDA approved Afluria Quadrivalent for use in persons 6 months of age and older.
  • FDA approved FluLaval Quadrivalent for use in persons 6 months of age and older.
  • FDA approved FluMist Quadrivalent, a live attenuated influenza virus (LAIV) nasal spray vaccine, for persons 2 through 49 years of age. This is the only LAIV nasal spray vaccine available for use during the 2021-2022 season.
  • FDA approved Fluarix Quadrivalent for use in persons 6 months of age and older.
  • FDA approved Flucelvax Quadrivalent for use in persons aged 2 years and older. This is the only cell-based inactivated influenza vaccine that has been licensed by the FDA for using during the 2021-2022 flu season.
  • FDA approved Flublok Quadrivalent, a recombinant vaccine, for use in persons 18 years of age and older.
  • FDA approved Fluzone Quadrivalent for use in persons 6 months of age and older.

For people 65 years of age and older

  • FDA approved Fluad Quadrivalent, an adjuvanted flu vaccine, for use in persons 65 years of age and older.
  • FDA approved Fluzone High-Dose Quadrivalent for use in persons 65 years of age and older. This is a quadrivalent vaccine that contains four times the antigen of standard-dose inactivated influenza vaccines.

Who should & should not get the vaccine

CDC recommends annual influenza vaccination for everyone 6 months and older with any flu vaccine licensed by the FDA that is appropriate for the recipient's age and health status. Vaccination is particularly important for people who are at high risk of developing serious complications from influenza.

Keep Reading: Who should & who should not get the flu vaccine

Common side effects

Injectable (inactivated influenza vaccines (IIV) and recombinant influenza vaccines (RIV))

  • Injection site reactions that include soreness, redness and swollen arm.
  • Fever.
  • Muscle Aches.
  • Headache.
  • Fatigue.

Nasal spray (live, attenuated influenza vaccine (LAIV)

In children

  • Runny nose.
  • Wheezing.
  • Headache.
  • Vomiting.
  • Muscle aches.
  • Fever (low grade).

In adults

  • Runny nose.
  • Headache.
  • Sore throat.
  • Cough.

When to call 911‎

Severe allergic reactions following vaccination are rare, but can be life threatening. If someone experiences symptoms of a severe allergic reaction, which can include hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, and weakness.

Vaccines, like any medicine, can have side effects. Many people who get an annual flu vaccine have no side effects at all. Most side effects from flu vaccination are mild and go away on their own in a few days without any treatment.

Report possible adverse events to VAERS‎
‎

The Vaccine Adverse Event Reporting System (VAERS) is an early warning system, co-managed by CDC and FDA, that monitors for potential vaccine safety problems. Healthcare providers and vaccine manufacturers are required by law to report certain adverse events (any side effect or health problem after vaccination that is concerning to you, even if you are not sure if the vaccine caused the event) following vaccination to VAERS; patients and caregivers can also submit reports.

Submitting a Vaccine Adverse Event Reporting System (VAERS) Report and Using VAERS Data

A closer look at the data

Fact‎

Findings from vaccine safety monitoring systems and scientific studies have shown that the flu vaccines have an excellent safety profile. Hundreds of millions of Americans have safely received flu vaccines for more than 50 years and the body of scientific evidence overwhelmingly supports their safety.

The safety of flu vaccines is monitored by CDC and FDA. Certain safety outcomes are commonly evaluated, including Guillain-Barré Syndrome, maternal and infant safety, and febrile seizures.

Guillain-Barré Syndrome (GBS)

The data on an association between seasonal inactivated influenza vaccine and GBS have been variable from season-to-season. When there has been an increased risk, it has been in the range of 1-2 additional GBS cases per million flu vaccine doses administered. The data also indicate that a person is more likely to get GBS after flu disease than after getting a flu vaccine.

Keep Reading: Vaccines and Guillain-Barré Syndrome (GBS)

Maternal and infant safety

Pregnant women are considered at high risk for developing serious complications from flu. Several studies have shown that influenza vaccination can protect pregnant women during and after pregnancy and protect the baby from influenza infection for several months after birth.

  • Using the Vaccine Safety Datalink (VSD), CDC conducted a study looking at the long-term outcomes of infants born to mothers who were vaccinated with tetanus, diphtheria and acellular pertussis (Tdap) and the influenza vaccine during their pregnancy. The study found that influenza and Tdap vaccines in pregnancy are not associated with an increased risk of hospitalization or death in infants during the first six months of life.1
  • CDC and other scientific institutions have conducted multiple studies that have examined the risk of miscarriage following influenza vaccination. The extensive body of evidence does not suggest a link between influenza vaccination and miscarriage.234
Keep Reading: Flu & Pregnancy

Febrile seizure

A CDC study showed that children aged 6-23 months had an increased risk for febrile seizure after simultaneously receiving inactivated influenza vaccine (IIV), pneumococcal conjugate vaccine (PCV) and diphtheria-tetanus-acellular pertussis vaccine (DTaP).5

Keep Reading: Vaccines and Febrile seizures

Narcolepsy following vaccinations in Europe (2009)

Key points‎

An increased risk of narcolepsy was found following vaccination with Pandemrix, a monovalent 2009 H1N1 influenza vaccine that was used in several European countries during the H1N1 influenza pandemic. This risk was initially found in Finland, and then other European countries also detected an association.

Background

Pandemrix is a monovalent 2009 H1N1 influenza vaccine manufactured by GlaxoSmithKline in Europe. It was specifically produced for pandemic 2009 H1N1 influenza. It was not used before 2009, and has not been used since the influenza pandemic season (2009-2010). It contains an oil-in-water emulsion adjuvant called ASO3.

An increased risk of narcolepsy was found following vaccination with Pandemrix. This risk was initially found in Finland, and then other European countries also detected an association.

Pandemrix was not licensed for use in the United States.

CDC vaccine safety efforts and research

In response to the events in Europe, CDC reviewed data from the U.S. Vaccine Adverse Event Reporting System (VAERS) and the Vaccine Safety Datalink (VSD) and found:

  • No indication of any association between U.S.-licensed H1N1 or seasonal influenza vaccine and narcolepsy.
  • That vaccination with influenza vaccines containing the 2009 H1N1 virus strain used in the United States was not associated with an increased risk for narcolepsy.5
  • No associations between adjuvanted pH1N1 vaccines (arenaprix-AS03, Focetria-MF59, and Pandemrix-AS03) and narcolepsy.6

How CDC monitors vaccine safety

CDC and the Food and Drug Administration (FDA) are committed to ensuring that vaccines provided to the public are safe and effective. Once vaccines are licensed or authorized for emergency use in the United States, CDC and FDA continuously monitor them through several safety systems.

Keep Reading: About CDC's Vaccine Safety Monitoring Program

Resources

Seasonal Influenza Vaccine Safety: A Summary for Clinicians
CDC Centers for Disease Control and Prevention Influenza Flu - vaccine safety summary provides an ov...
Guillain-Barré syndrome and Flu Vaccine
Overview of Guillain Barre Sydrome GBS, what causes it, and who is at risk of developing the disorde...
Thimerosal in Flu Vaccine
Oerview of the use of thimerosal in seasonal flu vaccines - CDC
Thimerosal and Vaccines
Answers to common questions about vaccine safety and thimerosal.
Contraindications and Precautions
Contraindications and Precautions: General Best Practice Guidelines for Immunization. Advisory Commi...
Immunization Schedules
Stay up-to-date on getting recommended vaccines. Here are immunization schedules for people of all a...
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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
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  2. Donahue, J. G., Kieke, B. A., King, J. P., Mascola, M. A., Shimabukuro, T. T., DeStefano, F., Hanson, K. E., McClure, D. L., Olaiya, O., Glanz, J. M., Hechter, R. C., Irving, S. A., Jackson, L. A., Klein, N. P., Naleway, A. L., Weintraub, E. S., & Belongia, E. A. (2019). Inactivated influenza vaccine and spontaneous abortion in the Vaccine Safety Datalink in 2012-13, 2013-14, and 2014-15. Vaccine, 37(44), 6673–6681. https://doi.org/10.1016/j.vaccine.2019.09.035
  3. Donahue, J. G., Kieke, B. A., King, J. P., DeStefano, F., Mascola, M. A., Irving, S. A., Cheetham, T. C., Glanz, J. M., Jackson, L. A., Klein, N. P., Naleway, A. L., Weintraub, E., & Belongia, E. A. (2017). Association of spontaneous abortion with receipt of inactivated influenza vaccine containing H1N1pdm09 in 2010-11 and 2011-12. Vaccine, 35(40), 5314–5322. https://doi.org/10.1016/j.vaccine.2017.06.069
  4. Irving, S. A., Kieke, B. A., Donahue, J. G., Mascola, M. A., Baggs, J., DeStefano, F., Cheetham, T. C., Jackson, L. A., Naleway, A. L., Glanz, J. M., Nordin, J. D., Belongia, E. A., & Vaccine Safety Datalink (2013). Trivalent inactivated influenza vaccine and spontaneous abortion. Obstetrics and gynecology, 121(1), 159–165. https://doi.org/10.1097/aog.0b013e318279f56f
  5. Duffy, J., Weintraub, E., Hambidge, S. J., Jackson, L. A., Kharbanda, E. O., Klein, N. P., Lee, G. M., Marcy, S. M., Nakasato, C. C., Naleway, A., Omer, S. B., Vellozzi, C., DeStefano, F., & Vaccine Safety Datalink (2016). Febrile Seizure Risk After Vaccination in Children 6 to 23 Months. Pediatrics, 138(1), e20160320. https://doi.org/10.1542/peds.2016-0320Duffy, J., Weintraub, E., Vellozzi, C., DeStefano, F., & Vaccine Safety Datalink (2014). Narcolepsy and influenza A(H1N1) pandemic 2009 vaccination in the United States. Neurology, 83(20), 1823–1830. https://doi.org/10.1212/WNL.0000000000000987
  6. Weibel, D., Sturkenboom, M., Black, S., de Ridder, M., Dodd, C., Bonhoeffer, J., Vanrolleghem, A., van der Maas, N., Lammers, G. J., Overeem, S., Gentile, A., Giglio, N., Castellano, V., Kwong, J. C., Murray, B. J., Cauch-Dudek, K., Juhasz, D., Campitelli, M., Datta, A. N., Kallweit, U., ... Shimabukuro, T. T. (2018). Narcolepsy and adjuvanted pandemic influenza A (H1N1) 2009 vaccines - Multi-country assessment. Vaccine, 36(41), 6202–6211. https://doi.org/10.1016/j.vaccine.2018.08.008