A new report by investigators with the US Centers for Disease Control and Prevention (CDC) details the administration of expired injectable influenza vaccines to nearly 200 patients in the United States from 2018 to 2019.
According to the report published in the Morbidity and Mortality Weekly Report
, seasonal flu vaccine doses have a standard expiration date of June 30, after which time vaccine formulations, including updated virus components matched to circulating viruses, become available. “Vaccination with an expired influenza vaccine might not protect against influenza infection because different influenza virus strains can be included in the vaccine each year; in addition, protection against viruses included in the vaccine could wane if vaccine potency decreases over time,” explain the authors of the report.
From July 11, 2018, to March 29, 2019, though, the Vaccine Adverse Event Reporting System (VAERS) received 125 reports of 192 patients in the United States who had received expired injectable influenza vaccines during the 2018–2019 flu season
. The report’s authors note that the number of expired vaccine doses administered during that period increased in September and decreased after October, which are the months when most people receive the flu vaccine.
The dates of vaccination among the patients receiving the expired flu vaccine ranged from July 2, 2018, to January 16, 2019. Information was available for 103 of the vaccine recipients, 73 of whom (70.1%) were identified as being in high-risk age groups for influenza. Of those patients, 5 were under the age of 5 years, and 65 were older than 50 years. There were also 6 reports of patients who had been pregnant at the time of vaccination, although pregnancy outcomes were not reported. In addition, of the 125 reports, there were 4 cases of adverse events after expired flu vaccine administration, although none were serious, and all were consistent with adverse events for seasonal influenza vaccine.
“Any person who receives an expired influenza vaccine should be revaccinated with the current season’s influenza vaccine,” the authors of the report write. “The VAERS adverse event findings suggest that expired [injectable influenza vaccine] does not pose additional risks for adverse events beyond those of seasonal [injectable influenza vaccine]. Vaccine failure was not assessed. In most reports, factors that contributed to administration of expired vaccine were not specified; however, 1 cluster of reports from a pharmacy stated that 4 persons received expired vaccine doses that had been mistakenly shipped from another pharmacy.”
Vaccines should be inspected for expiration before they are administered or transported to other facilities, the report notes, and facility vaccine coordinators need to be aware of the standard injectable influenza vaccine expiration date of June 30 and make plans for the safe disposal or return of any doses that remain after that date. Since the 1991 expiration of the Medical Waste Tracking Act
, state environmental agencies have set their own regulations for the safe disposal of expired vaccine vials. Unused vaccines that are not returned must be handled according to state requirements, which may include sending unused vials for incineration with a medical waste disposal company.
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