A trial of Pfizer Inc's experimental antiviral pill for COVID-19 was stopped early after the drug was shown to cut by 89% the chances of hospitalization or death for adults at risk of developing severe disease, the company said on Friday.

The results appear to surpass those seen with Merck & Co Inc's pill, molnupiravir, which was shown last month to halve the likelihood of dying or being hospitalized for COVID-19 patients also at high risk of serious illness. read more

Full trial data is not yet available from either company.

Pfizer shares surged 13% to $49.47, while those of Merck fell 6% to $84.69.