CDC advisors recommend steps to fill pertussis vaccine gaps

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Oct 27, 2010 (CIDRAP News) – A federal vaccine advisory group today approved recommendations to fill some gaps in pertussis vaccination as a way to further protect babies who aren't yet fully immunized.

The Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices (ACIP) moved the pertussis vaccine recommendations forward against a backdrop of rising pertussis infections in most states over the past several years and of surging infections in California, where the disease is near a 60-year high and has killed 10 babies.

ACIP member Mark Sawyer, MD, said that the ACIP pertussis vaccine working group has been addressing revised recommendations well before California's outbreak. Sawyer, a pediatric infectious disease specialist at the University of California at San Diego School of Medicine, said that some of their work last year was stalled by the group's urgent focus on the 2009 H1N1 vaccine.

California health officials are looking at pertussis vaccine strategies as a way to put a damper on the state's outbreak, said Dr Kathleen Harriman, with the immunization branch of the California Department of Public Health. "We need to vaccinate a lot of people around infants," she said.

Initial evidence from hospital surveys shows that cocooning strategies—vaccinating parents and others who are in contact with newborns—pushed by California during the outbreak have been effective, she said.

The state has so far received reports of more than 6,200 pertussis cases, which include 10 deaths among infants, she said.

ACIP's recommendations today are mainly aimed at shoring up gaps in two age-groups that Harriman aired concerns about: children ages 7 through 9 who are undervaccinated and for whom an approved pertussis vaccine doesn't exist and adults over age 64 who often take care of babies and also don't have an approved pertussis vaccine.

During deliberations today ACIP overwhelmingly voted to recommend:

  • Removing language in current recommendations about suggested intervals between receiving the tetanus-diphtheria (Td) vaccine and the tetanus, diphtheria, and pertussis (Tdap) vaccine
  • Permitting people older than 64 who have contact with infants younger than 12 months to receive a Tdap dose, even though the vaccines aren't yet approved for the age-group, and allowing those older than 64 who haven't received the Tdap vaccine to receive Tdap in place of the Td vaccine
  • Allowing children ages 7 to 10 years who aren't completely vaccinated against pertussis or for whom vaccination status isn't known to receive a dose of the Tdap vaccine, even though it isn't approved as a booster or catch-up vaccine for that age-group

The measure to remove interval language regarding the Td and Tdap vaccines will help remove a barrier to cocoon vaccination strategies. Parents targeted by hospital healthcare workers for pertussis vaccination often can't remember if and when they received their last Td or Tdap vaccine, said Dr Jennifer Liang, a member of ACIP's pertussis work group and an epidemiologist with the CDC's National Center for Immunization and Respiratory Diseases.

Liang said the working group's review of the research is reassuring, because it suggests that shorter intervals between the vaccines aren't linked to adverse effects and that the benefits of Tdap vaccination outweigh any interval-related risks.

During the discussion about pertussis vaccines for seniors, Liang said grandparents are increasingly becoming primary caregivers for babies, and people over age 64 should be considered in pertussis vaccine cocooning strategies, despite the lack of an approved vaccine for the older age-group. She also said pertussis infections in older people are likely underreported.

Representatives for Sanofi Pasteur and GlaxoSmithKline, two companies that make Tdap vaccine for the US market, presented data to the group showing that the vaccines are safe and effective in older people, and both said their companies are seeking licensure for use on those older than 64.

Some of the ACIP members predicted that the more permissive pertussis vaccine recommendation for seniors might give health officials more leeway in responding to outbreaks at nursing homes.

The final recommendation aimed at younger school children addresses what some health experts have called a "doughnut hole" in pertussis vaccine recommendations. Public health officials have a hard time shoring up pertussis protection in children ages 7 through 9 who haven't received all of their recommended doses or for whom the vaccination history isn't known. Currently, neither diphtheria, tetanus, and pertussis (DTaP) used for younger children nor the Tdap used for older children and adults is approved for this age-group.

Some at today's ACIP meetings expressed concerns about the wording of the recommendation, due to school districts' varied immunization policies. However, working group members said they would add clarifications when the recommendations are published.

In other ACIP developments today, members voted to recommend a booster dose of meningococcal vaccine for 16-year-olds, because protection seems to wane more quickly than originally thought, the Associated Press (AP) reported. Experts told the group that the vaccine is effective for less than 5 years, rather than a decade as originally thought.

Three years ago ACIP recommended that 11- or 12-year-olds receive the meningococcal vaccine, because the disease typically spreads in close quarters, such as school and dormitory environments.

The CDC typically accepts ACIP's recommendations. The groups meets tomorrow in the second day of its fall meeting, and the session will be live via webcast.

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