SAN DIEGO — Administering the pertussis vaccine just after birth, along with the hepatitis B vaccine, boosted infant antibody responses, even in babies born to mothers who had been recently vaccinated, researchers reported here.
In a randomized controlled trial, healthy infants who were given an pertussis vaccine within 5 days of birth were 13 times more likely to have detectable antibody levels compared with infants who were unvaccinated for the first 6 weeks of life, regardless of the mother’s vaccination status, according to Nicholas Wood, MBBS, PhD, MPH, of the University of Sydney in Australia, and colleagues.
In Australia, 60% of pertussis hospitalizations for infants younger than 1 year occur before the babies turned 10-weeks-old, Wood said in his presentation at IDWeek, a joint meeting of the Infectious Diseases Society of America (IDSA), the HIV Medicine Association (HIVMA), the Society for Healthcare Epidemiology of America (SHEA), and the Pediatric Infectious Diseases Society (PIDS).
Wood’s team recruited mothers who delivered healthy babies born after 36 weeks of gestation, and randomized the 398 healthy infants who were younger than 120 hours, or 5 days, to receive either the monovalent acellular pertussis (aP) and hepatitis B (HBV) vaccinations or HBV only.
The researchers tested for detectable (>5 EL.U/ml) IgG antibody responses to pertactin and pertussis toxin at 6 weeks and again at 10 weeks, but the primary outcome was antibody response rates at 10 weeks. Clinical outcomes such as rates of infection were not tracked, however.
All of the infants were given routine hexavalent combination diphtheria, tetanus, and pertussis (DTaP), Hib, Hep B, and polio vaccinations at 6 weeks, and again at 4 and 6 months.
Among babies in the aP/HBV group, 22% had mothers who had received a DTaP shot within the past 5 years, and among babies in the HBV-only group, 21% had mothers who had been recently vaccinated.
Pertussis toxin antibody levels were not detectable at the time of birth in 45% of mothers who had not received a DTaP in the past 5 years compared with 15% of mothers who had been vaccinated in the past 5 years, but still had undetectable levels of antibodies.
Ten weeks after initiation of the trial, detectable pertactin and pertussis toxin antibodies were found among 93% of infants who were given the aP/HBV vaccine, and in 51% of infants who were not vaccinated just around their time of birth (odds ratio 13.3, 95% CI 7.2-24.5, P<0.001).
Among infants born to mothers who had been vaccinated in the past 5 years, 92% of those who also received the aP/HBV vaccine after birth had detectable antibody levels, compared with 61% of those who only had the HBV. And out of the infants born to mothers who had not been given a DTaP vaccine in the past 5 years, 94% of the babies who were vaccinated with aP/HBV just after birth had detectable antibody levels compared with 48% of infants in the HBV only group (OR 13.1, 95% CI 7.1-24.1, P<0.001, for both comparisons).
No serious adverse events were reported. Minor vaccination site irritation was reported by 5% of those in the aP/HBV group, and 1% of the HBV-only group. Only one case of fever above 100.4 degrees was reported, which occurred in the HBV-only group. And 3% of aP/HBV and 4% of HBV-only patients sought any medical advice for the first week after the vaccination.
In a later analysis, when the babies were 8-months-old, 99% babies who had been given the aP/HBV vaccine, and three regularly scheduled vaccinations, had detectable antibody response levels for hepatitis B compared to 100% of babies who received the HBV-only vaccine, and three regularly scheduled vaccinations.
Wood said that they intended to follow-up with the cohort at 18 months and again at age 4 years.