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From The Medical Letter on Drugs and Therapeutics
November 6, 2019

Influenza Vaccine for 2019-2020

JAMA. Published online November 6, 2019. doi:https://doi.org/10.1001/jama.2019.18016

Annual vaccination against influenza A and B viruses is recommended for everyone ≥6 months old without a contraindication.1 Available vaccines for the 2019-2020 season are listed in the Table.

Seasonal Influenza Vaccines for 2019-2020
Seasonal Influenza Vaccines for 2019-2020

In the US, influenza vaccine should be offered by the end of October and continue to be offered for as long as influenza is circulating in the community. In most adults, serum antibody levels peak about two weeks after vaccination.1 Early vaccination (ie, in July or August) may result in suboptimal immunity before the end of the influenza season, especially in older adults. Children who require 2 doses should receive the first dose as early as possible, so that the second dose can be given by the end of October.

Live-Attenuated Vaccine

FluMist Quadrivalent, the intranasally administered live-attenuated influenza vaccine, is FDA-approved for use in healthy nonpregnant persons 2-49 years old (see “s” footnote in the Table for contraindications and precautions).

Recombinant Vaccine

Flublok Quadrivalent, a recombinant inactivated vaccine produced without the use of influenza virus or chicken eggs, contains three times the amount of antigen included in standard-dose influenza vaccines and is FDA-approved for use in persons ≥18 years old.

High-Dose Vaccine

Fluzone High-Dose, an inactivated trivalent vaccine that contains four times the amount of antigen included in standard-dose influenza vaccines, is FDA-approved for use in persons ≥65 years old. In a randomized, double-blind trial in 31 989 adults ≥65 years old during two influenza seasons, the high-dose vaccine induced significantly greater antibody responses than a standard-dose trivalent inactivated vaccine, and was 24.2% more effective in preventing laboratory-confirmed influenza illness.2

Adjuvanted Vaccine

Fluad, an adjuvanted inactivated trivalent influenza vaccine, is FDA-approved for use in persons ≥65 years old.3


The ACIP and the American College of Obstetricians and Gynecologists recommend vaccinating pregnant women against influenza without regard to the trimester of pregnancy,4,5 but they should not receive the live-attenuated vaccine.


The ACIP, the American Academy of Allergy, Asthma and Immunology, and the American College of Allergy, Asthma and Immunology state that any age-appropriate influenza vaccine can be administered to persons who report a history of hives related to egg exposure. Persons with more severe egg allergy can also receive any age-appropriate influenza vaccine, but they should be vaccinated in a healthcare setting with supervision by a healthcare provider experienced in recognizing and managing severe allergic reactions.

Immunocompromised Persons

The live-attenuated influenza vaccine should not be used in immunocompromised persons.

Adverse Effects

Influenza vaccination has been associated with Guillain-Barré syndrome, but the absolute risk is very low (about 1-2 additional cases per million persons vaccinated). Except for soreness at the injection site, adverse reactions to inactivated influenza vaccines are uncommon. The most common adverse reactions associated with the live-attenuated vaccine are runny nose, nasal congestion, fever, and sore throat. Nevertheless, persons who care for severely immunocompromised patients in protected environments should not receive the live-attenuated vaccine or should avoid contact with such patients for 7 days after receiving it.


Vaccination against seasonal influenza is recommended for all persons ≥6 months old, including pregnant women. Quadrivalent vaccines offer broader coverage against influenza B viruses. The intranasal live-attenuated vaccine is a recommended option for the 2019-2020 season. Recombinant, high-dose, and adjuvanted vaccines elicit greater antibody responses than standard-dose unadjuvanted vaccines in persons ≥65 years old, and the high-dose and recombinant vaccines have been shown to be more effective for prevention of laboratory-confirmed influenza in older persons in randomized controlled trials.

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Article Information

Published Online: November 6, 2019. doi:10.1001/jama.2019.18016

Once a month, The Medical Letter provides a previously published article to JAMA to be republished.

Previous Publication: The entire article was published in The Medical Letter on Drugs and Therapeutics. October 21, 2019;61(1583):161-165. It is reprinted here with permission from ©The Medical Letter Inc.

About The Medical Letter: The Medical Letter is a nonprofit organization that publishes biweekly new drug evaluations and treatment recommendations. The Medical Letter does not sell advertising or receive any commercial support. Financial support comes primarily from sales of subscriptions, books, software, continuing education materials, and licenses.

For a free trial subscription to The Medical Letter, go to www.medicalletter.org/tmlj. The Medical Letter—Essential to your practice.

Editors: Mark Abramowicz, MD, President; Gianna Zuccotti, MD, MPH, Vice President and Executive Editor; Jean-Marie Pflomm, PharmD, Editor in Chief

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. doi:10.15585/mmwr.rr6803a1PubMedGoogle ScholarCrossref
DiazGranados  CA, Dunning  AJ, Kimmel  M,  et al.  Efficacy of high-dose versus standard-dose influenza vaccine in older adults.  N Engl J Med. 2014;371(7):635-645. doi:10.1056/NEJMoa1315727PubMedGoogle ScholarCrossref
 Fluad—an adjuvanted seasonal influenza vaccine for older adults.  Med Lett Drugs Ther. 2016;58(1486):8.PubMedGoogle Scholar
CDC. Flu vaccination and addressing concerns pregnant women might have about flu vaccine safety. https://www.cdc.gov/flu/professionals/vaccination/vaccination-possible-safety-signal.html. Accessed August 28, 2019.
 ACOG Committee Opinion No. 732: influenza vaccination during pregnancy.  Obstet Gynecol. 2018;131(4):e109-e114. doi:10.1097/AOG.0000000000002588PubMedGoogle ScholarCrossref