UPDATE 1-Pfizer's Prevnar prevents pneumonia in elderly -study

(Adds details on vaccine, trial, pneumonia)

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 pneumoccocal 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.

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.

Company shares rose 1 percent to $31.77 in morning trading on the New York Stock Exchange, amid a 0.5 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 and Bernadette Baum)