Advisers to the U.S. Food and Drug Administration voted on Sept. 17 to recommend Covid-19 vaccine booster shots for Americans 65 and older and those at high risk of severe illness, after overwhelmingly rejecting a call for broader approval.

New York City will require public school teachers and staff to get vaccinated against Covid-19, Mayor Bill de Blasio said on Aug. 23, part of a push to get more residents inoculated and slow the spread of the highly contagious Delta variant.

California on Aug. 11 became the first U.S. state to require that its teachers and other school staff be vaccinated or regularly tested for Covid-19, a move Governor Gavin Newsom called “a responsible step” to ensure the safety of children.

Covid-19 vaccinations should be required for U.S. teachers to protect students who are too young to be inoculated, the head of the nation’s second-largest teachers’ union said on Aug. 8, shifting course to back mandated shots as more children fall ill.