Whooping Cough Vaccine Lags in Efficacy

Whooping Cough Vaccine Lags in Efficacy

By NICHOLAS BAKALAR

Whooping cough, or pertussis, is on the rise. In California, for instance, the incidence of the disease rose in 2010 to its highest level in 50 years. One reason may be the change from a whole cell vaccine to the currently used acellular version.

The whole cell vaccine had side effects, some mild (irritation at the vaccination site, for example) and some severe (seizures in about 1 in 2,000 cases). The new vaccine has been used since 1996.

Now a new study, published online in BMJ, has examined the effectiveness of the vaccine in 2010 and 2011 among people older than 11. The analysis included more than 32,000 Californians, and there were 668 laboratory-confirmed cases of pertussis.

The tetanus and diphtheria vaccines, which are given in a combination dose with the pertussis vaccine in a shot known as Tdap, are close to 100 percent effective. But the researchers found that the effectiveness of acellular pertussis in this age group was only 53 to 64 percent.

Still, the lead author, Dr. Roger Baxter, co-director of the Kaiser Permanente Vaccine Study Center, said the acellular pertussis is “a good vaccine, and a great tool for health care. But it could be better, and I hope that manufacturers begin work on a vaccine that has better effectiveness.”