For most of the second half of the 20th century, whooping cough was a disease of the past, one of many previously common infections practically eliminated by vaccines. Since the 1980s the bacteria has fought back, though, and now FDA researchers have a theory why--vaccines might not be stopping transmission.
The hunch is based on FDA research into the spread of whooping cough among baboons, animals that respond to the bacteria in a similar way to humans. Writing in the Proceedings of the National Academy of Sciences, the team reports that baboons given the acellular vaccine--which has been used in the U.S. since the 1990s--were more likely to transmit the bacteria than those who received the whole-cell version. The germ persisted for almost twice as long in the throats of baboons given the acellular vaccine.
Whole-cell vaccines were phased out amid safety concerns, but the study suggests that while its acellular replacement stops people feeling ill, it might not stop them transmitting the bacteria. The finding may explain the resurgence of whooping cough. "There were 48,000 cases reported last year despite high rates of vaccination. This resurgence suggests a need for research into … improved ways to prevent the disease from spreading," National Institute of Allergy and Infectious Diseases director Dr. Anthony Fauci said.
Sanofi ($SNY), which along with GlaxoSmithKline ($GSK) sells an acellular pertussis vaccine in the U.S., has questioned the applicability of the findings to humans. Others find the data more compelling though. "There's a difference between protecting individuals from illness and bringing down the incidence of pertussis in the population. To do both we may need a different vaccine," FDA microbiologist and co-author of the paper Tod Merkel told Science.