A report published in the journal Pediatrics suggests that Pfizer's Prevnar, or PCV7, hasn't made a visible dent in pneumonia, as reported in Yahoo!News.
In 1994, 19 in 1000 children got a pneumonia diagnosis at the doctor's office or at an emergency department, compared to 22 in 1000 in 2007.
However, earlier work found the number of children who had to be treated for pneumonia at the hospital dropped by more than half after the vaccine became available.
"It's possible that the vaccination has had a major impact on the more serious complications of pneumonia," said lead researcher Samir S. Shah, adding that "if you look at how effective the vaccine was in reducing meningitis and blood infections, it has done a phenomenal job."
However, Shah said Pfizer's new pneumococcus vaccine, PCV13, which replaced PCV7 on the childhood immunization schedule this year, is likely to afford better protection than its predecessor.