Vaccinating children could provide protection for older adults

Researchers at Vanderbilt University recently found that infant vaccination against pneumococcal bacteria significantly reduced pneumonia hospitalizations in older adults, according to a study published on Thursday in the New England Journal of Medicine.

In a study funded by the Centers for Disease Control and Prevention, researchers found that infant vaccination since 2000 reduced pneumonia hospitalization by more than 10 percent overall. The most significant drops in pneumonia hospitalization took place at the extreme ends of the age spectrum.

"Pneumonia is a leading cause of hospitalization in the United States," Marie Griffin, the study's first author, said. "The protective effect we saw in older adults, who do not receive the vaccine but benefit from vaccination of infants, is quite remarkable. It is one of the most dramatic examples of indirect protection or herd immunity we have seen in recent years."

The study found that after introducing pneumococcal conjugate vaccine, or PCV7, among infants, children under the age of two experienced a 40 percent drop in pneumonia hospitalizations. The study also showed 70,000 fewer annual pneumonia hospitalizations in 2009 than there were in the year 2000 among adults aged 85 and older.

"Humans are the only reservoir for the pneumococcus," Carlos Grijalva, the co-author of the study, said. "This group of bacteria can live in the nose and throat of healthy people, especially children. From young children, these bacteria may be transmitted to older age groups. Over time, the vaccine is causing a change in types of pneumococcus carried and transmitted nationwide. We are very fortunate to witness this in our time. These huge indirect effects on the adult population don't happen very often."

The researchers said they were optimistic that the newer vaccine that protects against 13 types of pneumococcus can keep providing direct and herd immunity effects moving forward.

"PCV13 may cause another large reduction in pneumonia hospitalizations; perhaps another 10 percent, we hope," Griffin said. "It is important for people to know that adults are benefiting from our childhood vaccine program. These are adults who won't be hospitalized, won't be getting antibiotics, or complications of hospitalizations, and won't be dying, since the risk of death is five percent to 12 percent when older adults are hospitalized with pneumonia. Vaccination of infants with pneumococcal conjugate vaccines results in a tremendous public health benefit."