The Emerging Infections Network (EIN) is a forum for infectious diseases consultants and public health officials to report information on clinical phenomena and epidemiological issues with public health significance. Any diagnostic or therapeutic recommendations and all opinions presented are those of the individual contributor. They do not necessarily represent the views of EIN, IDSA (EIN’s sponsor), or the Centers for Disease Control and Prevention (CDC), which funds EIN. The reader assumes all risks in using this information.
Members of EIN recently discussed pertussis immunization and what level of protection can limit the spread of the disease during an outbreak. Several members’ comments highlighted the need for more information regarding efficacy of the vaccine at both individual and population levels.
A member in Montana began the discussion, describing a local, ongoing pertussis outbreak in an area where immunization “is not the best. Now I am trying to determine what level of immunization will actually protect the kids (and contacts) from getting pertussis.”
How many doses of the diphtheria-tetanus-acellular pertussis (DTap) vaccine do children need “to give an adequate level of immunity against pertussis?” asked the member, who reported having pediatric patients who had had two doses in childhood, followed by the Tdap vaccine in junior high school within a year. “Is this going to confer enough protection so they don’t get sick or spread the disease?” the member asked. “These types of immunity questions are so vague that I can't find a close to solid answer. I hate to go with a gut feeling.”
Responding from Texas, an EIN member wrote that the current cellular vaccine, while safer, is not as efficacious as the previous vaccine. “In the long run we need a better vaccine.”
An Illinois respondent noted that “I don’t think there is a level of immunization that can be quoted to protect the kids and contacts from getting pertussis. My ‘gut feeling’ is to drive the immunization levels in the community as high as possible based on trying to get those eligible for immunization up to date,” the member continued. “That is the best I think we can do at this time, and ideally, it is what we should be doing in the absence of an outbreak to minimize the likelihood of one occurring.”
Currently, Tdap vaccine is approved only for a single dose, a respondent from California wrote, so giving additional doses in children 7 years of age and older is not an option. “I am sure this recommendation will change in the future,” the member added, “since we have seen a number of cases of pertussis in children who had a recent Tdap.”
A respondent from New Mexico noted that an August 2010 article in Clinical Infectious Diseases “suggests that the Tdap is about 66 percent effective for immunized children in an outbreak. More than immunization is needed for rapid outbreak control.”
An EIN member in Washington state also shared several journal articles that discuss “pertussis ‘herd’ and vaccine-induced immunity”:
Additional resources on pertussis are available from the Centers for Disease Control and Prevention:
HealthMap, a disease surveillance and mapping website created by a team at Children’s Hospital Boston, can also be searched for reports of pertussis outbreaks. The site brings together different data sources, including online news aggregators, eyewitness reports, expert-curated discussions, and official reports from public health authorities.
E-mail the Emerging Infections Network.
The Emerging Infections Network (EIN) is a provider-based sentinel network designed to help the public health community detect trends in emerging infectious diseases.
A joint project of IDSA and the Pediatric Infectious Diseases Society (PIDS) with funding from the Centers for Disease Control and Prevention (CDC), EIN tracks emerging infectious diseases and keeps the public health community up to date with new disease trends, difficult cases, and other issues affecting members’ clinical practices. The Network provides a great opportunity for members to share knowledge quickly across large geographical distances. Both IDSA and PIDS members are eligible to join. Click here for more information or to join EIN.
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