Can inactivated influenza virus vaccine be used after its expiration date?
FDA does not recommend the use of any vaccine beyond the labeled expiration date. The primary purpose of the expiration date is to ensure that vaccines used in clinical practice meet their release specifications, which ensures that they continue to be safe and efficacious. Release specifications include potency (strength), content of excipients, and sterility. The maintenance of vaccine release specifications over time (stability of the product) is monitored by each manufacturer for representative lots of influenza vaccine under controlled, documented storage conditions. The expiration date of a vaccine is based on these studies.
Although vaccine under proper storage conditions may maintain release specifications beyond the expiration date, the potency of inactivated influenza vaccines is generally declining gradually from the time of manufacture, and the rates of decline may vary. Variation in the rate of decline is partly related to differences in the specific strains used from year to year for vaccine production. An increased rate of decline occurs when the vaccine is exposed to temperatures outside the range recommended for optimal storage (generally 2-8