May 8, 2012 (Baltimore, Maryland) — Most adults don't know much about Tdap, which might explain the low uptake of the tetanus, diphtheria, and acellular pertussis vaccine, even though it is recommended for all adults, according to a Canadian study presented here at the National Foundation for Infectious Diseases 15th Annual Conference on Vaccine Research.

The vast majority (81%) of people polled in an online survey were not aware that a combined tetanus, diphtheria, and whooping cough vaccine exists, and 63% of respondents did not know that protection from childhood immunization wears off with time.

"The general public are apathetic, most likely because of a lack of knowledge," lead investigator Beth Halperin, RN, MN, assistant professor of nursing at Dalhousie University in Halifax, Nova Scotia, Canada, said. "You can't care about something you don't know about."

Despite widespread childhood vaccination, Bordetella pertussis remains an important cause of morbidity for people of all ages, including adults. In recent years, outbreaks in both Canada and the United States have indicated that the infection continues to circulate among adolescents and adults because of waning immunity. In turn, they spread the infection to infants who are at highest risk for severe pertussis infection. Canadian and American immunization advisory bodies currently recommend a single dose of Tdap (or DTaP) for all adults; however, anecdotal reports suggest that vaccination levels are low.

To understand the disconnect between the universal recommendation from Canada's National Advisory Committee on Immunization and the low vaccination rates, researchers assessed the general knowledge, attitudes, and beliefs regarding pertussis and the Tdap vaccine.

The findings come from a national Web-based survey of 4023 respondents 18 years or older. A follow-up was conducted with 8 national focus groups. Forty-eight percent of those surveyed online and 71% of the people in the focus groups had contact with children at home or work.

The study revealed that many survey respondents did not know genreal information about pertussis:

  • 64% were not aware of the national immunization advisory body's recommendation that all adults and adolescents get vaccinated to protect against pertussis

  • 62% did not know that adults can get whooping cough even if they had it as a child

  • 46% did not know that infants who have not received all their whooping cough vaccines are at high risk for the disease

  • 44% agreed that they were confused about whether they should get vaccinated for adult whooping cough.

This lack of knowledge appears to have shaped the public's beliefs and attitudes about the vaccine, Halperin noted. Only 6% of survey respondents believed they were at significant risk of contracting pertussis, and just 39% agreed that the Tdap vaccine is safe. The majority (60%) said they did not have enough information to decide whether to get the vaccine, and 39% said they do not plan to be vaccinated with Tdap.

Although the public doesn't know much about pertussis and the Tdap vaccine, information gleaned from the focus groups indicates that they are open to learning about vaccines from trusted healthcare providers. "It's not that they don't want to know," said Halperin. "It's that they don't have the information."

To make an informed decision, people want to know the risk of getting the disease, the worst-case scenario if they get whooping cough or pass it on to someone else, why a booster is needed, what is in the vaccine, and the adverse effects.

In addition, respondents say they want to know that it's not just a childhood disease, because that's how it's currently seen. They want to know why Tdap is recommended, why now, and how pertussis presents differently in adults and children. And they want to be told about waning immunity and what it means in terms of personal risk and risk to those around them.

They also wanted science made accessible to a broad audience. "They want to see the face of pertussis," Halperin noted. "What came through was that the protection of loved ones is important to them," she said. "It is this risk of potentially transmitting the disease to someone vulnerable that seemed to strike a chord with the participants."

"It's interesting to me that despite news of pertussis outbreaks, people still don't know much about the Tdap vaccine," moderator Susan Rehm, MD, medical director at the National Foundation for Infectious Diseases, told Medscape Medical News. Levels of Tdap immunization are abysmally low, she said, adding that she hopes the study will educate the public about how important it is to get vaccinated.

One of the interesting aspects of the study, Dr. Rehm noted, was the recognition that when people heard stories of suffering and death of infants because of pertussis, they were motivated to get vaccinated.

This study was funded by grants from GlaxoSmithKline and Sanofi Pasteur. Ms. Halperin reports receiving clinical research grants from GSK and Sanofi Pasteur. Dr. Rehm reports serving as an advisor or consultant for Merck & Co. and Pfizer, and as a speaker for Genentech.

National Foundation for Infectious Diseases (NFID) 15th Annual Conference on Vaccine Research: Session S7. Presented May 7, 2012.