Two key late-stage studies of Pfizer's blockbuster pneumococcal vaccine for children show it works well in adults, a market the drugmaker wants to target.
The studies of Pfizer Inc.'s Prevnar 13 vaccine against pneumonia, meningitis and other infections were presented at a medical conference in Milan, Italy.
Pfizer says they show it worked at least as well as an older pneumococcal vaccine made by Merck & Co.
Prevnar already is the world's top-selling vaccine. Prevnar 13, launched early last year, protects against 13 strains of pneumococcal disease, instead of just the seven covered by the original version, Prevnar 7.
The two versions had combined sales of about $3.7 billion last year. Pfizer hopes to boost that by a couple billion dollars.