Nearly 200 patients received expired flu vaccines during the last flu season, according to a CDC report published Friday.
The latest report covers data from July 11, 2018, to March 29, 2019.
According to CDC, influenza vaccines have a standard June 30 expiration date for the upcoming flu season—meaning a flu vaccine is good from July 1 through June 30.
One potential problem expired vaccines present is that they're not designed for the strains circulating in the current flu season, CDC said. Another potential problem, according to CDC, is that vaccine potency may decrease over time.
According to reports received by CDC's Vaccine Adverse Event Reporting System (VAERS), a spontaneous reporting surveillance system, 169.1 million doses of the seasonal flu vaccine were administered between July 11, 2018, and March 29, 2019.
During that time, VAERS received 125 reports that 192 patients were administered expired injectable inactivated influenza vaccines, according to CDC. CDC in the report said VAERS only reports a small number of flu vaccine injections, meaning expired flu vaccinations may be more common than the data suggest. In four cases, the expired vaccine caused an adverse event, but none of the effects were serious, CDC said.
According to CDC, recipients' ages were available for 103 cases. Of those, CDC found that about 70% were in high-risk age groups for influenza, meaning they were less than five years old or older than 50.
The report did not identify the factors that led to patients receiving expired vaccines. However, one group of reports from a pharmacy revealed that four patients received expired vaccine doses that were mistakenly shipped from another pharmacy, according to CDC.
Preventing future incidents
CDC in the report reminded providers that the standard expiration date for the upcoming flu season, set to begin July 1, is June 30. CDC also recommended that facilities inspect vaccines for expiration before administering doses to patients and dispose of or return any expired vaccine doses.
If patients do receive an expired vaccine, they "should be revaccinated with the current season's influenza vaccine," CDC said (Kommers, Becker's Clinical Leadership & Infection Control, 6/17; Duffy, Infectious Disease Advisor, 6/18; CDC's Morbidity and Mortality Weekly Report, 6/14).
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