Three DTaP doses cut young children’s whooping cough risk by 96%, CDC study finds

A CDC study of children caught up in an Alaskan outbreak found that those who had not been vaccinated were about 26 times more likely to develop laboratory-confirmed pertussis.

A new study from the US Centers for Disease Control and Prevention has found that young children who received at least three doses of the DTaP vaccine had 96.2% protection against whooping cough, a highly contagious respiratory illness caused by the bacterium Bordetella pertussis. The findings come as vaccination rates in the United States continue to drift lower, raising concern among public health specialists about the risk of outbreaks among the youngest children. According to the CDC analysis, children who were not vaccinated were around 26 times more likely to develop laboratory-confirmed pertussis than those who had completed the recommended course.

The research focused on children in Alaska during a statewide outbreak and examined those aged six months to six years. It compared children who had received three or more doses of DTaP with those who had either not been vaccinated or had received fewer doses than recommended. Even partial vaccination offered meaningful protection: children with one or two doses were 85.3% less likely to develop confirmed disease than unvaccinated children.

DTaP is normally given in five doses during childhood, starting at two months of age, with additional doses in infancy and early childhood and the final dose recommended between ages four and six. The CDC says the vaccine is designed to protect against diphtheria, tetanus and pertussis, and that side effects are usually mild and short-lived, such as soreness at the injection site, fever or fatigue.

Joseph McLaughlin, the study’s lead author and an epidemiologist with the Alaska Department of Health in Anchorage, said the vaccine was effective at preventing laboratory-confirmed pertussis in young children. The CDC also warns that whooping cough can be especially dangerous in small children, causing pneumonia, pauses in breathing, seizures, brain injury and, in severe cases, death. Repeated coughing fits can also lead to vomiting and, in some cases, broken ribs.