Nasal Spray Flu Vaccine Often Administered After Expiration Date

Patients who receive the live attenuated influenza vaccine (LAIV) this November may inhale an expired dose, research published in the September 5, 2014, Morbidity and Mortality Weekly Report suggests.

Relying on the Vaccine Adverse Events Reporting System (VAERS), researchers from the US Centers for Disease Control and Prevention (CDC) uncovered that 866 (18.4%) of the 4699 LAIVs administered intranasally between July 1, 2007, and June 30, 2014, were expired. In contrast, only 96 (0.02%) of 49,695 inactivated influenza vaccines (IIV) administered via injection across that time period were expired.

Despite that alarming statistic, the investigators noted 97.5% of expired LAIV administrations did not involve any documented adverse health events. Although the data did not indicate any health risk associated with receiving expired LAIV, the CDC still recommended revaccination with a valid dose.

The report authors pointed out that LAIV has a much shorter shelf life than IIV. While IIV expires 1 year after the influenza season for which it is produced, LAIV typically expires 18 weeks after it is released for distribution.

In the study, the researchers found the majority of expired live flu vaccines were administered during the first week of November, which is approximately 18 weeks from the vaccine’s July 1 distribution date. Due to the passive nature of the VAERS reports analyzed in the study, the investigators noted it “likely captures only a small fraction of expired LAIV administered, so this error might be more common than VAERS data indicate.”

“Health care providers need to be aware of the shorter shelf life of LAIV, and implement measures to avoid administering expired LAIV, especially from November and onward, when this error appears to be more common,” the researchers recommended.