Whooping Cough Outbreaks Tied to Parents Shunning Vaccines
Study finds that areas with high rates of nonmedical vaccine exemptions also had high number of cases
By Serena Gordon
MONDAY, Sept. 30 (HealthDay News) -- New research confirms what experts have suspected: The decision not to vaccinate children for nonmedical reasons can have far-reaching effects, including raising the risk of infections for other children and their families.
Researchers compared areas with significant numbers of parents who chose not to vaccinate their children for nonmedical reasons to areas that were affected by the 2010 whooping cough outbreak in California. They found that people living in areas with high nonmedical vaccine exemption rates were 2.5 times more likely to also be located in an area with high levels of whooping cough.
"Not vaccinating your child is not a benign decision. It has real health consequences to the individual child and to the community," explained study senior author Saad Omer, an associate professor of global health, epidemiology and pediatrics at Emory University in Atlanta.
Results of the study were published online Sept. 30 and will appear in the October print edition of the journal Pediatrics.
Whooping cough, also known as pertussis, is a highly contagious bacterial disease that attacks the respiratory system. Last year, the United States had the highest number of whooping cough cases since 1955, according to the U.S. Centers for Disease Control and Prevention. During 2012, the CDC received reports of 48,000 cases and 18 deaths, with most of the deaths occurring in infants.
Part of the reason there's been a resurgence in whooping cough is that the newer vaccine, which causes far fewer side effects than the old vaccine, doesn't work for as long as the older vaccine did, the researchers explained. Because of this, it's crucial that children receive vaccines and booster doses on schedule. If there's a delay in vaccination, the risk of whooping cough goes up.
In 2010, 9,120 cases of whooping cough, with 10 deaths, were reported in California. That was the highest number of whooping cough cases in that state since 1947, according to background information in the study. Factors that may have played a role in this outbreak include the waning immunity associated with the newer vaccine, better diagnosis techniques and the cyclical nature of whooping cough.
But, the researchers also wanted to see if the clustering of people who had nonmedical exemptions for vaccines played a role in the outbreak. Omer said that previous research has shown that there do tend to be clusters of people with nonmedical vaccine exemptions.
In California, the rate of such exemptions has risen from 0.77 percent in 2000 to 2.33 percent in 2010, according to the study. Still, the state has relatively high vaccination rates. Almost 91 percent of children entering kindergarten in 2010 had received all the required immunizations, the study authors pointed out.