Tdap Dose During Pregnancy Prevents Pertussis in Neonates, Infants Later

Regardless of whether it is received during the second or third trimester, a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination during pregnancy effectively prevents pertussis among neonates and infants aged younger than 2 months, according to a new study from Argentina.

Argentina had its highest pertussis incidence and mortality rates of the last decade in 2011. According to the study authors, 60% of deaths were among infants aged younger than 2 months. In response, beginning in 2012, it was recommended that all pregnant women in Argentina at 20 weeks of gestation or later receive a dose of the Tdap vaccine.

“Although recent studies suggest that maternal Tdap vaccination is effective at preventing infant disease, no data have come from low- or middle-income countries, nor from ones using whole-cell pertussis vaccines for primary immunization,” the researchers wrote.

To conduct their study, the researchers analyzed data on 71 patients aged younger than 2 months with pertussis and 300 matched controls who had visited any of 6 hospital sites from September 2012 to March 2016. 

Overall, 49% of the case patients’ mothers and 78% of the controls’ mothers received the Tdap vaccination during pregnancy. 

Vaccine effectiveness (VE) was estimated as (1 – odds ratio) × 100%. The overall Tdap VE was estimated at 80.7% (95% CI, 52.1%–92.2%).

The VE of Tdap was similar when administered during the second vs third trimester.

“Our findings demonstrate the effectiveness of this strategy in protecting infants during the susceptible period before primary immunization, and may be especially relevant for other middle-income and, potentially, low-income countries, including those where whole-cell vaccine is used,” the researchers concluded.

—Colleen Murphy

Reference:

Romanin V, Acosta AM, del Valle Juarez M, et al. Maternal vaccination in Argentina: tetanus, diphtheria, and acellular pertussis vaccine effectiveness during pregnancy in preventing pertussis in infants <2 months of age. Clin Infect Dis. 2020;70(3):380-387. https://doi.org/10.1093/cid/ciz217.