A recent preprint co-authored by the U.S. Centers for Disease Control and Prevention’s (CDC) U.S. Flu Vaccine Effectiveness Network Investigators finds that repeat annual influenza vaccines are associated with an increased risk of influenza infection.
The preprint authors initially wondered if vaccination timing and influenza infections in prior seasons may have contributed to repeat vaccinees’ increased risk of infection.
However, they concluded these factors “cannot fully explain the increased infection risk in repeat vaccinees compared with non-repeat vaccinees.”
