US health officials have approved Pfizer's new version of a blockbuster vaccine that fights pneumonia, meningitis and other diseases caused by pneumococcus bacteria, a company spokeswoman said.

Prevnar 13 was the most important experimental product the company acquired in last year's purchase of Wyeth. The vaccine fights 13 strains of streptococcus pneumoniae bacteria.   

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

BMO Capital Markets analyst Robert Hazlett has estimated sales for the Prevnar franchise will hit $3.7 billion in 2012. - Reuters