Changes on horizon regarding pregnant women, pertussis vaccines

AAP 2011 National Conference

BOSTON – Clinicians will likely see a shift in vaccination recommendations for pregnant women in the next few weeks, according to a speaker at the American Academy of Pediatrics 2011 National Conference and Exhibition.

Sarah S. Long, MD, who is Chief of the Section of Infectious Diseases at St. Christopher’s Hospital for Children, said that the changes, which are expected to be published in the Morbidity and Mortality Weekly Report in coming weeks, will likely recommend that all pregnant women who have been pregnant for more than 20 weeks should receive tetanus, diphtheria, and acellular pertussis vaccine (Tdap).

Long said these recommendations follow data by the CDC that noted more than 80% of expectant mothers are willing to get the vaccine, and the fact that a “cocooning strategy,” which was recommended by the CDC in 2006, did not sway vaccination rates in family members of new infants.

“This strategy has been completely ignored,” Long said, adding that many pregnant women are receiving the tetanus and diphtheria vaccine while pregnant already, and adding the pertussis component is expected to provide at least some antibodies to neonates.

Long said this change in strategy is important, because most pertussis-related morbidity and mortality in children occurs in those babies aged younger than 4 weeks, or those children who are too young to be vaccinated with the diphtheria, tetanus toxoid, and pertussis vaccine (DTaP).

Long also said there may be some issues once these recommendations are put into place, including a possible blunting of immune response to the babies’ first DTaP vaccination in the first 2 to 6 months of life, since this has already been demonstrated in some studies. However, the data seem to indicate although blunted responses occur initially to those babies who are exposed to Tdap in utero, their antibodies seem to catch up to those infants who were not exposed in utero by 15 months of age.

She noted, however, that the blunting is not likely to be a major cause of concern, because “I don’t particularly care where your antibody comes from as long as you have some, and this strategy is likely to protect very young infants from death.”

According to Long, changes in the recommendations for pertussis vaccine are needed, because “disease incidence in infants in rising and is severe.”

There are several reasons, according to Long, why the burden of pertussis disease is shifting to young infants, including partial control of pertussis, waning vaccine immunity, and failure to vaccinate. “We know there is a significant association with vaccine exemptors in schools and outbreaks of pertussis,” Long said. All of these challenges, coupled with the fact that “our current vaccine schedule leaves remarkable susceptibility for children younger than 4 months of age,” has led to a rising incidence of pertussis in very young infants.

Targeting pregnant women for vaccination is a good strategy, Long said, because other data have shown that giving pertussis vaccines at birth leads to interference with other vaccines, specifically, Haemophilus influenzae type b.

That is why the primary series currently includes 4 doses given at ages 2, 4, 6, and 15 to 18 months. A fifth (booster) dose is recommended when the child is aged 4 to 6 years. Also, booster doses of Tdap are recommended at ages 11-12. – by Colleen Zacharyczuk

Disclosures: Dr. Long reported no relevant financial disclosures.

David W. Kimberlin

Dr. Long provides a succinct summary of the issues that have led the CDC ACIP and AAP COID to recommend changes to the pertussis immunization recommendations to include all pregnant women who have not previously received a dose of Tdap. This change in policy will empower mothers to be able to do one more thing that may save the life of their baby, namely to protect them against the ravages of whooping cough. With California having recently experienced the worst whooping cough outbreak in 60 years, it is all of our hopes that women will take advantage of this opportunity in the same manner by which they do other things for the benefit of their babies.

David W. Kimberlin, MD
Infectious Diseases in Children Editorial Board member

For more information:

• Long S. #F2120. Pertussis: Persisting, Perplexing Problem. Presented at: AAP National Conference and Exhibition. Oct. 15-18, 2011. Boston.

Follow the PediatricSuperSite.com on Twitter.