Pfizer says late-stage trial of RSV vaccine proved effective in reducing risk in very young children

Pfizer Inc. said Tuesday a late-stage trial of its Respiratory Syncytial Virus, or RSV, vaccine proved highly effective in reducing the risk of severe disease for infants against a virus that causes hundreds of deaths a year. The Phase 3 trial found that the vaccine given to pregnant mothers achieved vaccine efficacy of 81.8% in infants from birth through the first 90 days of life. The trial found efficacy of 69.4% through the first six months of life, the company said in a statement. There is currently no vaccine available for RSV. Pfizer said it expects to make its first regulatory application for the vaccine by the end of 2022 and to follow on with other regulatory bodies. It will also submit the results of the trial for peer-review in a scientific journal. RSV is a common cause of respiratory illness and can affect the lungs and breathing passages of very young children by clogging them with mucus. Pfizer shares were up 1.4% premarket, and have fallen 21% in the year to date, while the s&P 500 has fallen 19%.

Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.