With limited options to treat people with COVID-19, the U.S government has also secured millions of doses of Pfizer Inc's(PFE.N)rival antiviral drug, which last week was shown to cut by 89% the chance of hospitalization or death for adults at risk of severe disease.
The vaccine is still highly effective in people six months after their second dose. Yet there is some evidence its efficacy might diminish over longer periods, and the shot isn’t as effective againstt he Delta variant, prompting research into adding a third dose