Getting pneumonia while you have the flu can be dangerous. It’s known as a coinfection, and in previous flu pandemics pneumonia has been a leading factor in deaths. Earlier in this year’s swine flu outbreak, some studies indicated that coinfection with pneumonia for the H1N1 virus was rare, but a new study of the autopsies of 77 patients who died from the swine flu found that 29 percent had coinfections of bacterial pneumonia.

The patients in this study weren’t selected randomly, so they don’t reflect the population overall. And the autopsies don’t reveal whether the cause of death was flu, pneumonia or both. But the study does show that pneumonia can play a role in the severity of disease for this year’s swine flu, and could even lead to death.

Pneumoccocal pneumonia is the most common bacterial pneumonia, and it can be prevented with a vaccine. Yet few Americans get vaccinated.

There are currently two vaccines available. The Centers for Disease Control and Prevention recommends the pneumococcal polysaccharide vaccine (PPSV; Pneumovax) for everyone over 65 and those from 2 to 64 years old with certain health conditions, such as chronic heart, lung, or liver disease, alcoholism, or impaired immunity. The PPSV is a single shot, with a 5-year booster for those who got it their first shot before they turned 65, or who are at very high risk. It offers protection against a wide spectrum of bacteria.