Vaccine refusal may have contributed to California’s 2010 pertussis outbreak, study finds

Vaccination exemptions for non-medical reasons, such as religious or philosophical beliefs, may have contributed to the pertussis epidemic that struck California in 2010, says a new study.

During that outbreak California saw 9120 cases and 10 deaths, accounting for more than one third of all cases of whooping cough seen in the United States that year.

Before the introduction of pertussis vaccines in the 1940s, the disease was the leading cause of childhood death in the US. In 1934, for example, the country saw more than 250 000 cases. After the introduction, the number of cases fell, reaching a low of 1010 in 1976.

In …