UPDATE 3-Pfizer wins U.S. approval for pneumonia vaccine

* Prevnar 13 was key product acquired from Wyeth

* Vaccine advisers recommend new shot

* Pfizer shares gain 0.8 percent (Recasts; Adds details on price, analyst comment, closing share price)

WASHINGTON, Feb 24 (Reuters) - Pfizer Inc's PFE.N new version of a blockbuster vaccine that fights pneumonia, meningitis and other infections won approval from U.S. health officials on Wednesday.

Government vaccine advisers recommended the new Prevnar 13 shot for infants who have not been immunized with the original. They also urged one dose for children up to age 5 who already received all four doses of the earlier vaccine.

Prevnar 13 was the most important experimental product Pfizer acquired in last year’s purchase of Wyeth. It fights 13 strains of Streptococcus pneumoniae bacteria, or pneumococcus.

The original Prevnar, which targeted seven strains, was introduced in 2000 and has annual sales around $3 billion.

Infections caused by pneumococcus greatly declined after the original Prevnar was launched. At the time, the seven targeted strains accounted for 80 percent of invasive pneumococcal infections in young children in North America.

By 2007, cases had dropped 99 percent in children younger than 5 years old, according to the Food and Drug Administration (FDA).

Studies also showed disease rates fell in unvaccinated people, especially the elderly.

“Although the rates of invasive pneumococcal disease have declined dramatically, there are still children in the United States who are suffering with this serious illness,” Dr. Karen Midthun, acting head of the FDA’s unit that reviewed Prevnar 13, said in a statement.

The new version “will help prevent pneumococcal disease caused by” the six additional strains, she said.

Pfizer has estimated that the added protection could reduce deaths from pneumococcus by an extra 9,800 over 10 years.

The new vaccine targets a strain called 19A that has emerged as the most common cause of pneumococcal infection in the United States. That strain is becoming harder to treat as it develops resistance to antibiotics, said Dr. Emilio Emini, Pfizer’s chief scientific officer for vaccine research.

Deutsche Bank analyst Barbara Ryan said approval of Prevnar 13 “was expected, and is an incremental opportunity for the current $3 billion Prevnar franchise.”

She said sales of the vaccine could grow to $4.5 billion a year if Prevnar 13 is approved for adults. Pfizer hopes to apply for approval for adult use by year’s end, Emini said.

Pneumonia caused by the pneumococcal organism is one of the biggest causes of death in older people and its incidence begins to increase after age 50.

The FDA approved the four-dose Prevnar 13 for infants and children ages 6 weeks through 5 years for preventing invasive diseases caused by the 13 strains. It also approved the vaccine for preventing ear infections caused by the original seven strains.

In studies in children, potential side effects were similar in Prevnar 13 and the original shot and included tenderness at the injection site and irritability.

Pfizer will charge private providers $108 for Prevnar 13, company spokeswoman Kristen Neese said.

Leerink Swann analyst Seamus Fernandez said the pricing was higher than he had expected and reiterated his “outperform” rating on Pfizer shares.

GlaxoSmithKline Plc GSK.L has a rival vaccine called Synflorix that is active against 10 strains. Synflorix is approved in Europe and some other markets, but not in the United States.

Merck MRK.N also sells the Pneumovax 23 vaccine, which fights 23 types of pneumococcus and is the only vaccine of its type that is FDA-approved for adults.

Pfizer’s shares rose 0.8 percent to close at $17.81 on the New York Stock Exchange. (Reporting by Lisa Richwine, Maggie Fox and Ransdell Pierson, editing by Gerald E. McCormick, Toni Reinhold and Carol Bishopric)