Herd immunity from GSK, Merck vaccines cutting hospitalizations

Researchers have previously linked GlaxoSmithKline ($GSK) and Merck's ($MRK) rotavirus vaccines to a drop in virus-related infant hospitalizations, but the benefit to other age groups was unclear. A U.S. Centers for Disease Control and Prevention (CDC) team has now dug into this topic.

The study looked at the numbers of rotavirus-related hospitalizations before and after the routine use of GSK's Rotarix and Merck's RotaTeq. Writing in the Journal of the American Medical Association (JAMA), CDC staff reported that, as expected, the number of hospitalizations of kids under 5 fell significantly. The 80% drop between 2000 to 2006 and 2008 to 2010 likely reflects the immunization of this age group. Hospitalizations of older children and adults fell too, though.

CDC found a 70% decrease in hospitalizations of kids aged 5 to 14 years old, despite this group being too old to be routinely immunized. Older people benefited too. Hospitalizations of adults aged 25 to 44 years old fell 43%, and there was a double-digit decline among the over-65 group. In July researchers found that Pfizer's ($PFE) Prevnar 7 and 13 pneumonia vaccines are having a similarly pronounced effect on hospitalizations of unvaccinated populations.

Both studies are evidence of the herd immunity provided by vaccines. "This study confirms the benefits of the rotavirus vaccine program, but it also shows there's an unexpected benefit to the population at large. This is one example of what we call herd immunity. By vaccinating young children you prevent them from getting sick, but you also prevent them from transmitting [rotavirus] to their siblings and their parents," CDC's Ben Lopman told Reuters Health.

- read Reuters' article
- check out NPR's take
- view the JAMA abstract

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