U.S. might not formally change definition of fully vaccinated soon, but booster shots become a fact of life in more places as research suggests benefits against new variant
Omicron is changing the definition of what it means to be fully vaccinated because early studies suggest that current Covid-19 vaccines will require three doses to offer sufficient protection against the variant.
Yet given resistance to vaccinations, requiring a booster dose could be a thorny decision for policymakers and health authorities.
