A new study published this week in the New England Journal of Medicine shows that vaccines given to children to prevent blood and ear infections are reducing the spread of pneumonia to older, at-risk adults. In fact, Vanderbilt University researchers found that the herd immunity effect from the vaccination of children was more effective in preventing pneumonia than a vaccine currently given to prevent pneumonia in the elderly.

“Pneumonia is a leading cause of hospitalization in the United States,” said Dr. Marie Griffin, lead author of the study and a professor of Preventive Medicine at Vanderbilt. “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 looked at a U.S. national database for pneumonia hospitalizations from 1997 to 2009. Since the PCV7 vaccine was added to the childhood vaccine list in 2000, children age 2 and under saw a 40% reduction in hospital visits due to pneumonia. At the same time, pneumonia hospitalizations for adults over 65 accelerated, and by 2009 made up over half of the overall decline in hospitalizations for pneumonia.

The PCV7 vaccine protects against seven types of pneumonia and bacteria that cause ear and lung infections in young children. Though researchers are worried that less common types of pneumonia not covered by the PCV7 vaccine could become more prevalent, this study provides evidence that the replacement for PCV7 introduced in 2010, PCV13, could provide another large reduction in hospitalizations from pneumonia.

“PCV13 may cause another large reduction in pneumonia hospitalizations; perhaps another 10 percent, we hope,” said Griffin. “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 5 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.”