Expired Flu Shots: 192 Patients Reported to VAERS in the 2018–19 Season

Everyone 6 months and older is recommended to get a flu vaccine every year. Each season's injectable inactivated influenza vaccine (IIV) carries the same expiration date: June 30 — the end of the flu season that runs from July 1 to June 30 of the next year.

An expired flu shot might not protect you, for two reasons: the virus strains in the vaccine can change from year to year, and protection against the strains it does contain could fade if the vaccine loses potency over time.

What VAERS received

From July 11, 2018, to March 29, 2019, the Vaccine Adverse Event Reporting System (VAERS) received 125 reports covering 192 patients given expired IIV during the 2018–19 season. Over that time, 169.1 million doses of seasonal flu vaccine were distributed.

Reports with documented dates of administration of expired injectable flu vaccine, July 2018–January 2019 (102). CDC

So an expired IIV does not appear to add risk beyond that of an in-date one. Whether it failed to protect was not assessed.

How it happened

Most reports didn't say why. In one pharmacy cluster, four people got expired doses that another pharmacy had shipped by mistake. Seven reports said patients were offered a new dose of the current season's vaccine; three confirmed they got it.

VAERS depends on people choosing to report, so it likely catches only a small fraction of expired shots — the error may be more common than these numbers suggest.

How to prevent it

• Rotate stock and check regularly for expired doses; remove expired vaccines and diluents at once.
• Check the expiration date before giving a vaccine or sending it to another facility.
• Vaccine coordinators should know about the June 30 expiration and plan to dispose of or return leftover doses after it. Unused vaccine can sometimes be returned for credit even when it must be thrown away — ask the state immunization program or the manufacturer.
• Anyone given an expired flu vaccine should be revaccinated with the current season's vaccine.

CDC's Vaccine Storage and Handling Toolkit has more guidance.

Sources

Based on Hesse EM, Hibbs BF, Cano MV, "Notes from the Field: Administration of Expired Injectable Influenza Vaccines Reported to the Vaccine Adverse Event Reporting System — United States, July 2018–March 2019," MMWR volume 68, number 23, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The report gives the 73 high-risk recipients as 70.1% of the 103 with known ages, which those two numbers do not produce, so only the counts are given here.