The science on Omicron is starting to settle, so what does it reveal about the new dominant strain’s infectiousness, mortality and vaccine resistance.
Booster shots are rolling out across much of the world to spur protection against COVID-19, prompting questions about when exactly they should be given.
A booster shot given several months after the immune system has been primed by an initial series usually two doses of a vaccine can invigorate its response, a leading expert said.