Against the backdrop of a recent nationwide increase in pertussis cases, a CDC analysis reveals that only 5.9% of adults aged 18 to 64 years received the tetanus, diphtheria, and pertussis (Tdap) vaccine in 2008, three years after the agency first recommended the shot.

According to the agency, the Tdap vaccine serves as a one-time substitution for the traditional 10-year booster dose of the tetanus, diphtheria vaccine. The shot can protect adults against pertussis and prevent the transmission of the disease from health-care workers to patients and from adults to infants. During this year’s pertussis outbreak in California, nine infants had died by mid-October.

CDC representatives advise providers to recommend Tdap for persons aged 18 to 64 years whose most recent tetanus shot was at least 10 years earlier. They also recommend that health-care workers with direct patient contact and persons with infant contact be vaccinated as soon as feasible, at intervals as short as two years since their most recent tetanus vaccination. Others aged 18 to 64 years can get the Tdap vaccine within 10 years of their most recent tetanus vaccination to protect against pertussis.