States that easily grant exemptions or offer personal belief exemptions have higher nonmedical exemption rates than states that offered only religious exemptions. The study is published in the October 11, 2006, issue of the Journal of the American Medical Association.
Pertussis is caused by a bacterial toxin that is spread easily through person-to-person contact, coughing and sneezing. It is more severe in infants and young children, who consequently have a greater risk of pneumonia, seizures, encephalopathy (a brain disorder) and other potentially deadly complications. Pertussis, which is characterized by severe coughing, is endemic in the United States. The incidence of the disease has increased nationwide in the last 20 years, with 25,827 cases reported in 2004, according to the CDC.
“In states that make exemptions widely available or easy to obtain, there has been an increase in the number of children who were not immunized. This is a disturbing trend; previous research has shown that school immunization requirements have played a major role in controlling vaccine-preventable diseases in the United States,” said Saad B. Omer, MBBS, MPH, lead author of the study and an assistant scientist in the Johns Hopkins Bloomberg School of Public Health’s Department of International Health.
The researchers examined long-term data on state-level exemption rates at school entry. They also analyzed the incidence of pertussis for individuals 18 years of age or younger from 1986-2004 for the 48 states that permit nonmedical exemptions and the District of Columbia. The study authors found that nonmedical exemption rates were higher and increasing in states that permitted exemptions based on personal belief and in states where exemption processes were less arduous. Those states were also strongly associated with a higher incidence of pertussis.