Pertussis Vaccination at Birth?

Pertussis has long been known to cause severedisease and death in infants, especially in thosewho are unvaccinated or who are too young tobe immunized. With the number of pertussiscases in the United States increasing,¹ those ofus who care for susceptible infants are looking for solutionsto this dangerous problem.

Some physicians consider immunizing women beforepregnancy or immediately postpartum to reducethe risk of infant exposure and to potentially providepassive immunity to the child. Others encourage boostershots for close contacts of young infants. With thebooster shot now included in the recommended scheduleof routine immunizations of teenagers and adults,it is hoped that the amount of pertussis present in thecommunity will decrease.

In a study recently published in the Journal ofPediatrics, Knuf and colleagues² took a different approachto the pertussis situation by examining the effects of adose of acellular pertussis vaccine given shortly afterbirth. In this double-blind controlled study performed inGermany, 121 healthy infants were randomized to receiveeither a dose of acellular pertussis vaccination or hepatitisB vaccination between days 2 and 5 of life. Both groupswere then given DTaP-HBV-IPV/Hib at ages 2, 4, and6 months. All vaccines given were manufactured byGlaxoSmithKline, which supported the study.

The researchers measured antibody concentrationsin patients before the first vaccine dose, and then againat ages 3, 5, and 7 months. They also had parentsrecord any signs and symptoms for 8 days after eachvaccine to look for adverse reactions. Signs and symptomswere then graded for severity by the investigators.

Among infants given a birth dose of acellular pertussisvaccine, there was no decrease in immune responsivenessto pertussis after the primary vaccine course.In fact, there was an accelerated response that persistedagainst all 3 pertussis antigens until 5 months, andfor 1 pertussis antigen until at least 7 months. Whencompared with infants given a birth dose of hepatitis Bvaccine, however, those who received acellular pertussishad a decreased antibody response to hepatitis B virus.It is unclear whether this decrease was the result of havingreceived 1 fewer hepatitis B vaccine dose or to areduced response to the antigens presented. Among theacellular pertussis group, there was also a decrease inresponsiveness to Haemophilus influenzae.

After the birth dose, no significant statistical differencein adverse reactions was seen between the acellularpertussis group and the hepatitis B group. Fever didnot develop in infants in either group, although some ineach group were irritable, drowsy, and had localized erythema.After the remaining 3 vaccine doses, there weresimilar rates and severity of adverse events between the2 groups.

The Knuf study has many limitations-including thesmall study size, withdrawal of patients, and lack of a controlgroup that did not receive any vaccines at birth. However,it does address an interesting method of reducingpertussis-related morbidity and mortality in infants.

By providing vulnerable newborns with an antibodyresponse to a dangerous bacterium, we could potentiallyreduce the impact of this disease. The birth dose of acellularpertussis was well tolerated . . . but if it decreasesimmunity to H influenzae, are we only trading one dangerousscenario for another?

Until further studies are done, we will have to continueto encourage booster shots among adolescentsand adults-especially in women of childbearing ageand close contacts of babies-to protect young infantsfrom pertussis.

References:

• Centers for Disease Control and Prevention. Pertussis. http://www.cdc.gov/ ncidod/dbmd/diseaseinfo/Pertussis_t.htm. Accessed May 12, 2008.

• Knuf M, Schmitt HJ, Wolter J, et al. Neonatal vaccination with an acellular pertussis vaccine accelerates the acquisition of pertussis antibodies in infants. J Pediatr. 2008;152:655-660.