This year, the U.S. is going to have the worst outbreak of whooping cough (pertussis) since 1959, according to a new report from the CDC. It s a resurgence that is very troubling, since it most likely reflects a further decline in the rate of routine immunizations in certain regions of the country although other factors may be responsible as well.
So far this year, an estimated 18,000 cases of whooping cough have been reported about half of which occurred in infants younger than 3 months. Such young children must rely on herd immunity (protection for the unvaccinated derived from high immunity rates for the whole community) for protection against the disease, since they cannot yet be vaccinated.
Even more troubling, however, are data demonstrating an abnormally high number of pertussis cases in 13- and 14-year-olds, an age group that normally is less affected by the bacterium.
What factors, then, can account for this sudden increase in pertussis? One possibility is that the protective effects of the new pertussis vaccine, one of the components in the TDaP vaccine (adopted in 1997), may not be as long-lasting as the original one, which was developed in the 1930s. Furthermore, studies in California show that the vaccine s immune benefits have dropped from 95 percent to 70 percent within five years.
A new version of the vaccine was developed in response to fears of potentially harmful side effects associated with the original vaccine. However, these side effects were extremely rare and did not pose any serious health threat to those vaccinated. Despite the scientific evidence, the U.S. switched to the new vaccine anyway, as it was believed to have fewer side effects. But as ACSH s Dr. Gilbert Ross points out, If the protection conferred by the newer vaccine is in fact of shorter duration and has contributed to the current, and other recent, outbreaks of pertussis, the switch may have just created unanticipated problems.
In addition to the possibly diminished efficacy of the reformulated vaccine, fear-based anti-vaccine campaigns have discouraged some parents from getting their children vaccinated, which no doubt has contributed to the current pertussis epidemic. Children who do not receive their vaccines put the population at large at great risk of infection. This problem is particularly prevalent in those states which allow so-called philosophical exemptions from mandatory vaccination. Unbelievably, there are still twenty states that allow to this unscientific and dangerous option.
Although Dr. Anne Schucat, director of the CDC s National Center for Immunization and Respiratory Diseases, denies that such anti-vaccination campaigns are the main problem, it is hard to believe that they have had no effect. For instance, in April, pertussis was declared an epidemic in the state of Washington one of 20 states that allows philosophical vaccine exemptions. Coincidence? We think not.
The increase in pertussis cases further demonstrates why it s imperative for everyone to keep their immunizations current. Teenagers and adults should be getting their booster shots, while parents need to make sure that their kids are fully up to date with their vaccine schedules.
It is unacceptable for children not to be vaccinated, says Dr. Ross, since they are exposing friends, classmates, and newborns to this totally preventable contagion.
