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Influenza
Protects against the flu; offered as a shot and, in recent years, as a nasal spray.

What’s new: The nasal spray, while sometimes available as a painless alternative to the needle, was not recommended for use in the U.S. last year and may not be this year, either.

Why: Data from the past few flu seasons revealed that the spray, which contains a weakened live form of the influenza virus, didn’t work as well as the shot with the inactive virus. Scientists are investigating potential causes for the disparity, says Sandra Fryhofer, MD, an internist in Atlanta and member of the CDC’s influenza work group. The flu vaccine’s ability to prevent illness can vary from season to season. Look for updates about this year’s recommendation soon at cdc.gov/flu and plan to get your shot by the end of October, according to the CDC.