(Adds details on standard Pneumovax vaccine, updates share price, final two paragraphs)
By Ransdell Pierson and Caroline Humer
Feb 24 (Reuters) - Pfizer Inc said on Monday that Prevnar 13, its blockbuster vaccine against childhood infections, prevented pneumonia outside of hospitals in people age 65 and older, in one of the largest drug trials ever conducted.
The 85,000-patient study, called CAPiTA, also showed that Prevnar 13 prevented invasive pneumococcal disease, meaning infections of Streptococcus pneumoniae bacteria in the bloodstream and other normally sterile sites in the body.
Wall Street analysts have predicted that success of the trial would boost annual sales of Prevnar 13 by $1 billion or more, as doctors steer elderly patients to the product.
"We expect the U.S. and other developed markets to broadly recommend adult use of the product," given favorable results from the study, J.P. Morgan analyst Chris Schott said in a research note.
Schott said he expects Prevnar 13 sales among adults of $300 million in 2015, rising to $1.5 billion in future years as it is more widely used for that population.
An estimated 300,000 adults aged 50 and older are hospitalized every year because of pneumococcal pneumonia, a substantial cause of illness and death, according to the U.S. Food and Drug Administration.
Prevnar 13, sold under the brand name Prevenar 13 in many markets outside the United States, is one of Pfizer's biggest products. The drug, and an older version of the vaccine known as Prevnar 7, have annual sales of $4.4 billion, making them the company's second-biggest franchise.
During the trial, Prevnar 13 met its primary goal of preventing a first episode of community-acquired pneumonia. It also met a secondary goal of preventing a first episode of invasive bloodstream infections, which are typically far more severe than pneumonia without such bloodstream involvement.
Pfizer said data from the study, conducted in the Netherlands, would be presented at a medical meeting in India next month.
The FDA in early 2010 approved Prevnar 13, to protect children against additional strains of Streptococcus pneumoniae bacteria that cause an array of diseases, including pneumonia, ear infections and meningitis.
But the U.S. health regulator in late 2011 widened the approved use of Prevnar 13 to include adults age 50 and older, to prevent pneumonia and invasive infections. The approval was conditioned, however, on success of the now-completed CAPiTA study.
Favorable data from the study are expected to be added to the package insert label of Prevnar 13, greatly boosting the attractiveness of the vaccine to doctors with elderly patients.
Tim Anderson, an analyst with Sanford Bernstein & Co, said relatively few adults have yet been vaccinated with Prevnar 13. He predicted adult sales will rise to $1.3 billion in 2020 and that total sales of the Prevnar franchise will rise to $6 billion that year.
The standard pneumonia vaccine, Pneumovax from Merck & Co , is approved to prevent pneumococcal disease in patients 50 years and older and children as young as 2 at risk of pneumococcal infections. But it is not considered highly effective.
Pfizer shares rose 1.7 percent to $31.99 in trading on the New York Stock Exchange, amid a 0.7 percent gain for the ARCA Pharmaceutical Index of large U.S. and European drugmakers. (Reporting by Ransdell Pierson and Caroline Humer; Editing by Jeffrey Benkoe, Bernadette Baum and Jonathan Oatis)