Pfizer begins testing omicron-matched COVID shots in adults

By LAURAN NEERGAARD
AP Medical Writer

Pfizer and BioNTech have begun studying a COVID-19 vaccine tweaked to match to the omicron variant in healthy adults. COVID-19 vaccine makers have been updating their shots in case global health authorities decide a change is needed. The study announced Tuesday will include more than 1,400 volunteers ages 18 to 55. Most already are vaccinated and will get boosters of the omicron-based vaccine or the original version. Some unvaccinated volunteers will get three omicron-based doses. The original vaccines still offer good protection against severe illness and death. And a booster improves the chances of avoiding even a milder infection.