A really intriguing study suggesting a non-specific general health effect of live vaccines was just published in JAMA.
The study compared a half million children immunized with the MMR vaccine as their most recent vaccine compared to DTap-IPV-HiB. The hypothesis tested was that MMR, with its live components, would have a non-specific immune enhancing effect due to greater immune stimulation than with the killed vaccine. To assess this the incidence of hospitalization for any infection was determined.
The researchers found a statistically protective effect (IRR 0.86) with those who received MMR as their most recent vaccine.
What this study may have uncovered is a non-specific immune boosting effect of live vaccines. If true, it may mean that live vaccines should be placed in the immunization schedule at the times most opportune to provent childhood morbidity, as suggested by an accompanying editorial.
Further, the animus that the anti-vaccine movement has against live vaccines has again shown to be completely unfounded and not reality based.