Nov 5 (Reuters) - A trial of Pfizer Inc"s (PFE.N) experimental antiviral pill for COVID-19 was shown to cut by 89% the chances of hospitalization or death for adults at risk of developing severe disease, a "stunning" result that potentially adds another weapon to combat the pandemic. Following are the reactions from leaders and public health experts: U.S. PRESIDENT JOE BIDEN "If authorized by the FDA we may soon have pills that treat the virus in those who become infected. We"ve already secured millions of doses. The therapy would be another tool in our toolbox to protect people from the worst outcomes of COVID."BRITAIN"S HEALTH SECRETARY SAJID JAVID "Incredible results from Pfizer showing their antiviral medicine cuts the risk of hospitalization or death from COVID-19 by almost 90%." "We have procured 250,000 doses of this promising treatment on behalf of the UK and our independent medicines regulator, the MHRA, will now assess its safety, quality and effectiveness." WHITE HOUSE CHIEF OF STAFF RONALD KLAIN (On Twitter) "This still needs review by FDA and approvals." "But with vaccines for children 5-11 now getting started, and the prospect of an antiviral this effective, this could be a turning point week in our fight against COVID." ASHISH JHA, DEAN OF THE BROWN UNIVERSITY SCHOOL OF PUBLIC HEALTH (on Twitter) "Just stunning results ... Implications of effective therapeutics for ending the pandemic are very, very large." DR. ERIC TOPOL, A PROFESSOR OF MOLECULAR MEDICINE AND DIRECTOR OF THE SCRIPPS RESEARCH TRANSLATIONAL INSTITUTE "This is even bigger than the Merck drug." "This one knocked it out of the park - 89% versus 50%. But also, they had different endpoints, 8% in the placebo group for the Pfizer, 14% in Merck ... This is huge, because now we"re going to have two drugs." FORMER FOOD AND DRUG ADMINISTRATION COMMISSIONER AND PFIZER BOARD MEMBER SCOTT GOTTLIEB (on Twitter) "We have an overwhelming therapeutic toolbox to eliminate death and suffering from Covid. For U.S., the end of the pandemic is now in clear view, and secure. We need to evenly distribute this triumph of science over disease around the world, and make sure this never happens again." WHO CHIEF SCIENTIST SOUMYA SWAMINATHAN (on Twitter) "Good to see new oral antivirals being developed for #COVID19. To have global impact, will need early diagnosis of infection (rapid diagnostics) plus affordable access to these new drugs." MIZUHO SECURITIES EQUITY ANALYST VAMIL DIVAN "Oral treatment options would complement, not cannibalize, the vaccine even as questions have been raised on how the oral medicines might impact vaccine sales." "The oral treatments will be an important option for patients who are either unvaccinated or vaccinated and looking to reduce their risk of severe illness, especially if they are at high risk for severe illness."