An extremely contagious respiratory illness, pertussis puts infants at greatest risk for severe complications, including death. More than half of infants younger than 1 year old who get pertussis are hospitalized, according to the Centers for Disease Control and Prevention (CDC), and 1 or 2 in 100 hospitalized infants die. Immunity is difficult to maintain in the community because infants cannot be vaccinated until they are 2 months old. As a result, they may be at risk, especially from family members and care givers who have the disease.

In their study, Hung Fu Tseng, PhD, MPH, and his team at Kaiser Permanente Southern California found that adverse events following Tdap vaccination in seniors were mostly minor. "Although there is a small increased risk of injection site reaction following Tdap vaccination in the elderly, it is no more common than that following the traditional tetanus and diphtheria (Td) vaccine," Dr. Tseng said.

The researchers' study included 119,573 seniors who received the Tdap vaccine and the same number of people who received the traditional Td vaccine. Safety data were collected from seven health maintenance organizations across the U.S. The risk for adverse events following vaccination was comparable among both groups.

The authors hope the findings will allay any fears among older adults about the safety of the Tdap vaccine and prompt more doctors to urge across-the-board immunization, which is crucial in the wake of recent pertussis outbreaks, such as those in Minnesota, Washington state, Wisconsin, and elsewhere. Current recommendations call for infants older than 2 months, children, teens, adults (including pregnant women, parents, and health care workers), and those over 65 to be vaccinated.

"Pertussis immunization is important, particularly since one of the most common sources of pertussis in infants is their relatives, including their grandparents," Dr. Tseng said. "We suggest that clinicians follow CDC's recommendation and talk to older adult patients about vaccination against pertussis to protect themselves and their family members."