Vaccine refusal tied to pertussis outbreak

Refusal to vaccinate children against whooping cough might have played a role in the 2010 pertussis outbreak in California, researchers reported. Analysis of the outbreak — the largest in the state since 1947 — showed that pertussis cases fell into two large temporal and spatial clusters, according to Saad Omer, MBBS, PhD, of Emory University in Atlanta, and colleagues. And a 5-year analysis of so-called nonmedical exemptions from vaccination for children entering kindergarten found 39 spatial clusters, Omer and colleagues reported in the October issue of Pediatrics. The two types of clusters tended to overlap, Omer and colleagues found, suggesting nonmedical exemptions might have been “one of several factors in the 2010 California pertussis resurgence.” Several other possible causes of the outbreak have been put forward, including the notion that the acellular vaccine now used is less effective than the older whole-cell medicine. Researchers have also suggested that even if it has the same initial...