2010 California Pertussis Outbreak Linked to Vaccine Refusal

New evidence regarding a 2010 California pertussis outbreak suggests that many people's refusal to get the whooping cough vaccine may have been a critical cause of the health issue.

The extremely contagious respiratory disease was the largest outbreak the country has seen in over 60 years, according to various reports, resulting in 9,120 cases and 10 deaths. In fact, statistics show that this outbreak alone counted for a third of all cases in the United States that year.

Several causes of the outbreak are linked to a waning immunity of the pertussis vaccine. A recent analysis also offers evidence that highlights information regarding geographic regions and the intentional refusal of the vaccine and increased cases of the disease.

Data from the California Department of Public Health looks at non-medical exemptions for children entering kindergarten from 2005 through 2010 and pertussis cases that were diagnosed in 2010 in California.

This analysis looked at 39 statistically significant geographic clusters that showed high rates of non-medical exemptions and two statistically significant areas of high pertussis cases. The report also showed that census districts within an exemption cluster were 2.5 times more likely to be in a pertussis cluster.

Various factors put areas at higher risks for clusters, including high socioeconomic status, lower population density, lower average family size, lower percentage of racial or ethnic minorities and higher median household income.

The study authors conclude that the refusal to receive a pertussis vaccine can put populations at a greater risk for the problem or even death, particularly seen in the elderly or infants.

Pertussis, also more commonly known as 'whooping cough', is an endemic disease in the United States that comes to a head every 3 to 5 years with frequent outbreaks, according to the Centers for Disease Control and Prevention (CDC). 

More information regarding this analysis can be found via Pediatrics.