More than four million.
That’s how many people have been killed by COVID-19 globally as of Thursday. At least, that’s the officially reported number. As SARS-CoV-2, the coronavirus that causes COVID-19, continues to spread, it is mutating. It is those new strains of the virus that are largely driving the latest surges in unvaccinated populations around the world.
As dangerous variants of the virus emerge, public health officials are increasingly concerned about the capacity of the virus to mutate into versions that fully vaccinated people might not be protected from. Vaccines are still providing high levels of protection against the known variants, and are particularly good at preventing severe illness in fully vaccinated people—the vaccines’ infection-blocking mechanism has remained effective, for now.
“The worst case scenario is that a variant develops that can escape the protection from the vaccine,” says Brandon Dionne, assistant clinical professor of pharmacy and health systems sciences at Northeastern. “That’s what we’re really worried about.”
That’s already happening to some extent—although not to a concerning level yet, Dionne says. There have been more breakthrough cases of COVID-19 reported in fully vaccinated people since the Delta variant has been circulating than when earlier versions of the virus were dominant.
Hospitalised with covid, how long to get off oxygen and released?
Covid recovery 
Sats low during flight + CFTR variant unknown significance
