A significant number of expired doses of live attenuated influenza vaccine doses were administered between 2007 and 2014, according to a recent MMWR report.
Because the live attenuated influenza vaccine (LAIV) has a relatively short shelf life, LAIV may be more likely to be administered after its expiration date than inactivated influenza vaccine (IIV).
CDC explored this hypothesis by analyzing reports to the Vaccine Adverse Event Reporting System (VAERS) of expired LAIV administered from July 2007 through June 2014.
Of the 4,699 LAIV reports, 18.4% reported administration of expired vaccine. Approximately 98% of these reports did not cite any adverse events. Vaccination occurred after the first week in November, approximately 18 weeks from July 1, in 95.1% of expired LAIV reports.
Contrastingly, 0.02% (n=96) of 49,695 IIV reports involved administration of expired vaccine.
VAERS is a passive surveillance system, so it is likely the reports represented a small fraction of expired LAIV administered, according to Penina Haber, MPH, of the CDC’s National Center for Emerging and Zoonotic Infectious Diseases, and colleagues, who wrote the report.
“Health care providers need to be aware of the short shelf life of LAIV and implement measures to avoid administering expired LAIV, especially from November onward, when this error appears to be more common,” the researchers concluded.
Disclosure: The researchers report no relevant financial disclosures.