The seven-strain pneumonia vaccine used in the U.S. beginning in 2000 has prevented 168,000 hospitalizations for the disease each year since, and its effectiveness showed no signs of waning, a new study concludes.
The biggest benefit, by far, was seen among people age 85 and older, for whom the so-called 7-valent pneumococcal conjugate vaccine, marketed as Prevnar, prevented 73,000 hospitalizations annually.
Children under two years old were also major beneficiaries - an estimated 47,000 pneumonia hospitalizations were prevented per year - a reduction of 43 percent compared to before the vaccine was available, according to the findings published in the New England Journal of Medicine.
"This is only the hospitalizations," lead author Dr. Marie Griffin of Vanderbilt University Medical Center in Nashville, Tennessee, told Reuters Health. "This is only one piece of what this vaccine is doing. It's also preventing ear infections and outpatient visits. It's really an amazing vaccine."
She and her colleagues calculated that in all age groups, about 12,000 deaths were also prevented annually over the past 12 years, but most were among people 75 years and older. In that age group, pneumonia is fatal for 7 to 12 percent of those who get it.
A newer vaccine, Prevnar 13, that protects against six additional pneumonia strains has been in use since 2010. As a result, "there's an expectation there will be another big decline," Griffin said in a telephone interview.
The fact that hospitalization rates declined - and remained low - after the seven-strain vaccine was added to U.S. immunization schedules alleviates concerns that other strains not covered by the vaccine would become more common, the researchers said.
"The worry was that the (strains) not included in the vaccine may actually take over and that didn't happen, so this was good news," Dr. Paul Goepfert, director of the Vaccine Research Clinic at the University of Alabama at Birmingham, told Reuters Health by phone. He was not involved in the new study.
Griffin and her colleagues also found that, for all age groups, the time spent in the hospital for pneumonia treatment was a bit shorter after the vaccine was introduced.
The vaccine's effect on hospitalization rates for children ages 5 to 17 years old and adults 18 to 39 was not significant, but those groups had the lowest rates before the vaccine was introduced.
Pneumonia accounted for just over four percent of all U.S. hospitalizations that didn't involve childbirth before the original seven-strain vaccine was introduced.
Griffin pointed out that the reduction in elderly hospitalization rates happened despite the fact that children are the only group who are routinely vaccinated against pneumonia.
"This was a very nice demonstration of herd immunity," Goepfert said. "It's neat that a vaccine in kids can protect adults."
He added that the findings offer more evidence that doctors can use to encourage parents who may be reluctant to get their kids vaccinated.
"The clinician can say, 'This is not only helping your child, it's helping the adults around your child,'" said Goepfert.