Public health agencies in many developed countries began to recommend the acellular vaccine in the late 1990s.
During 2006 and 2011, they found, the acellular vaccine protected only 53 to 64 percent of kids who got it.
These kids typically got five doses of the acellular vaccine spread out from age 2 months to 7 years.
Neither of the other groups showed any severe symptoms, but those that received the acellular vaccine retained live pertussis microbes in their nasal cavities, meaning they could still transmit the disease, and they did in fact give it to other healthy baboons.
Teenagers who were vaccinated with four doses of acellular vaccines
were at almost six times higher risk of pertussis than were those who had received four doses of whole-cell vaccines.
The three acellular vaccines found to be highly effective in the NIAID studies contained pertactin, a purified, 69-kilodalton (69kDA) protein from Bordatella pertussis, the bacterium that causes pertussis.
Until these studies, only limited data on the efficacy and safety of acellular vaccines in infants were available.
The acellular vaccines have been shown to have fewer side- effects than whole-cell pertussis vaccines, but until now the acellular had not been tested for safety and efficacy against whole-cell vaccines in large, well-controlled clinical trials.
Based on this data, scientists predict that acellular vaccines will become the cornerstone of new combination vaccines that will require fewer doses and will protect children against numerous diseases.
The Company believes that efficacy results reported today dispel the previously held perception that whole-cell pertussis vaccines are more effective than acellular vaccines
The Food and Drug Administration is expected to approve the acellular vaccines for infants shortly.
The NIH plans to launch a clinical efficacy trial to see how well the acellular vaccines perform as adult boosters, according to David Klein of the National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Md.