Vaccinated Adults Less Likely to Die from Pneumonia

Adults hospitalized for pneumonia who have received the pneumococcal vaccine are at a lower risk of dying from the disease than those who haven't been vaccinated, according to an article in the April 15 issue of Clinical Infectious Diseases, now available online. Prior vaccination also reduces patients' risk of developing medical complications and decreases their length of stay in the hospital.

Pneumococci, or Streptococcus pneumoniae, are bacteria that colonize the nose and throat, often without causing harm. When they do cause infection, however, it can be serious, sometimes resulting in pneumonia that could be fatal to people who are elderly or vulnerable due to other illnesses.

Researchers from Pennsylvania, Texas, and New Jersey analyzed data from nearly 63,000 patients hospitalized for pneumonia between 1999 and 2003. Twelve percent of the patients were known to have received pneumococcal vaccination prior to being hospitalized, 23 percent were unvaccinated, and the rest had unknown vaccine status.

Vaccinated patients were 40 to 70 percent less likely to die during hospitalization than either unvaccinated patients or patients with unknown status. Vaccinated patients also had a lower risk of developing respiratory failure, kidney failure, heart attack, or other ailments. In addition, vaccinated patients' average hospital stay was two days shorter than that of unvaccinated patients.

Adult pneumococcal vaccination is somewhat controversial, according to lead author David Fisman, MD, of PrincetonUniversity, because "it's been very hard to show that it prevents pneumonia, especially in older adults." However, the benefits of vaccination seem evident in the new study. "When people hit the door really sick and most likely to die, even in those people, being vaccinated was associated with a lower risk of death," Fisman said. The pneumococcal vaccine impairs the development of a serious condition called bacteremia, or bacterial infection of the bloodstream. "Even if you're really sick, prevention of the bacteria getting into the bloodstream...might save your life," Fisman said.

The Centers for Disease Control and Prevention (CDC) recommends that adults age 65 and older should get the pneumococcal vaccination, as should younger people with certain medical problems. CDC's "Healthy People 2010 program sets a goal of having 90 percent of older adults vaccinated by 2010. "Among older people, we think that about 60 percent of those who ought to get the vaccine actually get it," Fisman said. "According to our results, reaching the CDC's 'Healthy People 2010' targets for pneumococcal vaccination would be expected to save thousands of lives, and prevent tens of millions of dollars in healthcare expenses each year."

Even though it's not clear whether the pneumococcal vaccine can ward off pneumonia, the known advantages make the case for vaccination. "Whether or not it prevents pneumonia is almost irrelevantit clearly has an effect on reducing death in the individuals who get pneumonia," said Fisman.

Source: Infectious Diseases Society of America (IDSA)