patient care perspectives

Clinical Reactions and Serologic Response Following Influenza Vaccination in Pediatric Patients

by Mark H. Sawyer, MD

Overview

Parental concerns about vaccine safety and efficacy often fuel vaccine hesitancy. However, serious clinical reactions from vaccines, including those for influenza, are rare and the benefits of influenza vaccination are clear. Our featured expert discusses clinical reactions and serologic responses to influenza vaccination, with a focus on the pediatric population.

Expert Commentary

Mark H. Sawyer, MD, FAAP, FIDSA

Professor of Clinical Pediatrics
Division of Infectious Diseases
University of California, San Diego, School of Medicine
Rady Children’s Hospital-San Diego
San Diego, CA

“Most people who receive the influenza vaccine do not experience any problems. Some reactions are more common in certain age groups, such as syncope from injected vaccines among adolescents. Serious allergic reactions from any vaccine are estimated at approximately 1 in 1 million doses.” 

Mark H. Sawyer, MD, FAAP, FIDSA

We do not completely understand why the influenza vaccine does not work equally well from one year to the next, and there are many theories on this. Some data suggest that yearly vaccination eventually results in weaker immune protection compared with intermittent vaccination; other data suggest that influenza vaccine-induced immunity may fade before the end of the flu season. The live attenuated influenza vaccine (LAIV) induces mucosal immunity, which many people believe is very important for protection, and the localized response may result in better protection against influenza viruses that have changed during the course of the season. The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices, as well as the American Academy of Pediatrics, are again including the LAIV among the recommended options for the 2019-2020 influenza season based, in part, on serologic data suggestive of high effectiveness.

With respect to clinical responses and side effects, most people who receive the influenza vaccine do not experience any problems. The inactivated influenza vaccine and the recombinant influenza vaccine are administered intramuscularly, and virtually all of the common side effects—including muscle soreness, redness, and/or swelling at the site of injection; headache; nausea; and muscle aches—disappear within the first day or so. Serious clinical reactions from vaccines, including those vaccines for influenza, are extremely rare; serious allergic reactions from any vaccine are estimated at approximately 1 in 1 million doses. The same is true of Guillain-Barré syndrome and the theoretical risk of Reye’s syndrome with the LAIV—these serious reactions are extremely rare. Some reactions are more common in certain age groups, such as syncope from injected vaccines among adolescents. Something about the hormones at that age seems to make a fainting type of reaction more likely in response to the acute pain of injection. The Centers for Disease Control and Prevention recommends that providers consider observing patients (seated or supine) for 15 minutes following vaccination to decrease the risk for injury should syncope occur. Syncope is less of an issue with the LAIV because there is no injection. But the attenuated virus in the LAIV replicates in the nasal lining, which can cause a runny nose, nasal congestion, and, sometimes, a mild sore throat and a low-grade fever. All of these side effects are generally mild and self-limiting. Early clinical trials indicated that the LAIV could trigger an asthma exacerbation in young children, so the LAIV should not be used in those with a history of severe asthma or wheezing. I personally have never seen a child hospitalized because of an asthma attack triggered by the LAIV. But it is something to keep in mind.

References

American Academy of Pediatrics News. AAP: no flu vaccine preference for 2019-’20 season. https://www.aappublications.org/news/2019/03/14/fluvaccine031419. Accessed October 23, 2019.

Bartoszko JJ, McNamara IF, Aras OAZ, et al. Does consecutive influenza vaccination reduce protection against influenza: a systematic review and meta-analysis. Vaccine. 2018;36(24):3434-3444.

Centers for Disease Control and Prevention. Possible side effects from vaccines. https://www.cdc.gov/vaccines/vac-gen/side-effects.htm. Accessed October 23, 2019.

Committee on Infectious Diseases. Recommendations for prevention and control of influenza in children, 2019–2020. Pediatrics. 2019;144(4): e20192478.

Grohskopf LA, Alyanak E, Broder KR, Walter EB, Fry AM, Jernigan DB. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices - United States, 2019-20 influenza season. MMWR Recomm Rep. 2019;68(3):1-21.

Henninger ML, Kuntz JL, Firemark AJ, Varga AM, Bok K, Naleway AL. Feasibility of a pilot intervention to reduce pain and syncope during adolescent vaccination. Vaccine. 2018;36(27):3937-3942.

Mohn KG, Smith I, Sjursen H, Cox RJ. Immune responses after live attenuated influenza vaccination. Hum Vaccin Immunother. 2018;14(3):571-578.

Sawyer MH, Simon G, Byington C. Vaccines and febrile seizures: quantifying the risk. Pediatrics. 2016;138(1):e20160976.

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