Pertussis in Infants and Maternal Vaccination
Severe pertussis disease is primarily seen in infants under 6 months of age. 16 cases in this age group have accounted for only 12% of cases but 83% of hospitalizations in Orange County cases in 2018 (see Table 1). Adolescent and adult illness rarely requires hospitalization, but these populations serve as a community reservoir for the bacteria.
Of 8 pertussis cases in infants ≤2 months of age, only one (13%) had a mother who received Tdap (tetanus, diphtheria, acellular pertussis) vaccination at the appropriate period during pregnancy. Tdap is recommended for all pregnant women during weeks 27-36 weeks of gestation for each pregnancy. The effectiveness of maternal Tdap vaccination in preventing infant disease is clear, with multiple studies estimating an effectiveness of up to 93% in preventing disease.* On a statewide and local level, however, immunization rates for pregnant women are disappointing. According to a recent survey
just over 50% of pregnant women in Orange County received Tdap at the correct time during pregnancy, which is similar to rates seen around the country.
*Studies evaluating effectiveness of maternal vaccination in preventing newborn pertussis:
A Case-Control Study to Estimate the Effectiveness of Maternal Pertussis Vaccination in Protecting Newborn Infants in England and Wales, 2012-13, Dabrera G, et al. Clinical Infectious Disease 2015 Feb 1;60(3):333-337.
Impact of the US maternal tetanus, diphtheria, and acellular pertussis vaccination program on preventing pertussis in infants <2 months of age: A case-control evaluation. Skoff TH, et al. Clinical Infectious Disease 2017 Nov 29;65(12):1977-1983.
California Maternal and Infant Health Assessment, 2016, can be found at: