ATLANTA (FRONTLINE MEDICAL NEWS)Pertussis vaccination does not eliminate the risk of disease, but it does appear to reduce disease severity, according to findings from a study of more than 10,000 cases.

In fact, despite high acellular pertussis vaccine coverage in the United States, 48,277 cases were reported in 2012, and many of these were among vaccinated individuals – a result of waning protection over time following childhood pertussis vaccination, Lucy A. McNamara, Ph.D., of the Centers for Disease Control and Prevention in Atlanta reported at the International Conference on Emerging Infectious Diseases.

To assess whether severe symptoms or complications are more common in those who are not fully vaccinated, Dr. McNamara and her colleagues identified a total of 10,092 pertussis case patients from the Enhanced Pertussis Surveillance/Emerging Infections Program network in 2010-2012 and collected case information through vaccine registries and interviews with physicians and patients at six network sites. Of those aged 3 months to 19 years, 81% were up to date for pertussis vaccinations for their age, and of adults, 45% had received Tdap.

Up-to-date status was protective against severe disease, defined as disease involving seizures, encephalopathy, pneumonia, or hospitalization, in children aged 7 months to 6 years, who had about a 60% reduction in risk, compared with those who were not up to date. Up-to-date status also reduced the risk of posttussive vomiting, which sometimes accompanies severe coughing fits, by about 25% in those aged 19 months to 64 years, she said, adding that the risk of vomiting after coughing was about 38% lower in this age group when patients received antibiotic treatment within 1 week of the start of the illness.

The effect on posttussive vomiting was independent of antibiotic treatment timing, which further underscores the value of both rapid treatment and completion of the pertussis vaccination schedule, she said.

Dr. McNamara reported having no disclosures.