Importance of immunizing whole family against pertussis revealed

A new study released in the April issue of The Pediatric Infectious Disease Journal, about the transmission of pertussis (commonly known as whooping cough), found that household members were the source for 71%-82% of cases among infants for whom a source case could be identified. The study demonstrates the importance of vaccination of close contacts of infants to reduce the number of infant pertussis cases and potentially save lives.

The study, the first simultaneous evaluation of infant pertussis conducted in four countries (including the USA) was led by researchers at the University of North Carolina, Chapel Hill and was supported by Sanofi Pasteur, the vaccines business of French drugs giant Sanofi-Aventis. This was conducted over a 20-month period and found that, among infants with pertussis for whom the source could be identified, 55% were parents, followed by siblings (16%), aunts/uncles (10%), friends/cousins (10%), grandparents (6%), and part-time caregivers (2%). In previous studies, identifying the source of infection was hindered by incomplete case data and less comprehensive laboratory evaluation of contacts.

"While pertussis cases in all age groups have been rising, it is important to know how the disease is spread, particularly to infants who are too young to be vaccinated themselves, so that steps can be taken to prevent infections in these vulnerable" said Annelies Van Rie, assistant professor of epidemiology in the UNC School of Public Health. "It is troubling to learn that infants are often infected with pertussis by their own family members, who are often unaware of having pertussis themselves," she noted.