The effectiveness of whooping cough vaccination wanes after the final dose, a new study that examined the safety of the shots has called for fresh look at the vaccine and the guidelines.
Whooping cough or Pertussis is a highly bacterial disease. The disease starts mildly with a sore throat and then slowly develops into a severe cough, making high-pitched whoop sound in the infected person.
The disease spreads from one to another when the infected person sneezes or coughs. Small and unvaccinated children are at higher risks of developing the contagious disease than others and the infection can prove to be life threatening in some cases.
Though antibiotics can be used to treat the disease during the early stages, vaccination is the prime protection against its occurrence. Normally, DTaP (diphtheria, tetanus and acellular pertussis) vaccine is administered to children in five doses - two, four, six, 15-18 months and four- six years. Single dose vaccine Tdap is available for children aged between 11 and 18 and adults aged between 19 and 64.
DTaP vaccine, a combination of diphtheria and tetanus toxoids, was one of the early vaccines against pertussis. Though the four doses of the vaccine was 70 to 90 percent effective, a majority of the children experienced side effects like swelling and pain after taking the vaccination. This led to the development of more purified or acellular pertussis vaccines with fewer side effects.
Investigators from the Kaiser Permanente Vaccine Study Center, Oakland, examined the risks of the disease among children in California from 2006 to 2011, including the 2010 pertussis outbreak. They included 277 children aged between four and 12, who were vaccinated with DTaP between 47 and 84 months of age.
At the end of the study, the researchers found the effectiveness of the vaccine decreasing 40 percent each year, making it less than 50 percent effective by the time children start going to kindergarten.
"All the findings point to the fact that vaccine guidelines and pertussis control measures may need to be reconsidered," Kaiser Permanente Vaccine Study Center co-directors Roger Baxter and Dr. Nicola Klein, said in a news release. "These results point to the need for new and improved pertussis vaccines."
Results of the study have been published in The New England Journal of Medicine, Sept.13.
