SAN DIEGO, CA—Neonatal acellular pertussis vaccination may be a safe alternative to maternal immunization, according to efficacy data presented at IDWeek 2015.

Nicholas Wood, MB BS, DCH, MPH, FRACP, PhD, from the University of Sydney, Sydney, Australia, explained that a newborn’s first 12 weeks of life carry the highest risk of death and hospitalization from pertussis, with 60% of infants hospitalized by the time they are 10 weeks old. Maternal vaccination during pregnancy or the vaccination of both parents immediately after birth (“cocoon strategy”) are currently implemented to protect infants.

Dr. Wood and colleagues assessed immunogenicity and safety in a trial that randomized healthy newborns >36 weeks’ gestation within 120 hours of birth to GlaxoSmithKline’s 3-component acellular pertussis vaccine and hepatitis B vaccine (aP vaccine group; n=221) vs. the hepatitis B vaccine alone (control group; n=219).

All participants received routine hexavalent combination vaccine including DTaP, Haemophilus influenza type b (Hib), hepatitis B vaccine, and polio antigens at 6 weeks, 4 months, and 6 months; in addition, pneumococcal vaccines were administered at 6 weeks, 4 months, and 6 months, and the rotavirus vaccine at 6 weeks and 4 months.

The majority of mothers had not received Tdap vaccine (n=308), while 90 had received the vaccine within 5 years of delivery and prior to pregnancy.

Researchers measured IgG antibody responses to pertussis toxoid (PT), pertactin (PRN) and filamentous hemagglutinin (FHA) in mothers at time of delivery and in infants at Weeks 6 and 10, and Months 6 and 8. The a priori primary outcome variable was detectable PT and PRN at Week 10.

Data showed that detectable PT was 93.2% at Week 10 for the aP vaccine group vs. 50.8% for the control group. For the maternal TdaP vaccine group, PT was 91.5% vs. 61.4% and, for no maternal TdaP vaccine, 93.7% vs. 47.7%. Antibody responses to PRN were higher at 10 weeks for the aP vaccines vs. the control group.

The team reported no vaccine-related serious adverse events occurred, with comparable reactogenicity profiles between the aP and control groups.

Dr. Wood presented five key study findings: 1) significantly higher pertussis antibody levels in infants by 10 weeks of age; 2) a trend to higher pertussis antibody levels by 6 weeks of age; 3) vaccine administration is safe; 4) higher maternal antibody results in lower postprimary infant responses, similar to what has been observed in other studies, with the vaccine reducing the impact of the maternal antibody; and 5) evidence of interference to concomitant antigen responses.

“Birth aP vaccine offers additional protection in the absence of maternal Tdap vaccination,” he concluded.