Nearly all newborns who received an acellular pertussis-only vaccine at birth showed titers for pertussis and no difference in adverse events, compared with a group receiving only the hepatitis B vaccine, a randomized clinical trial from Australia has found.

Pertussis copyright Jacopo Werther/Wikimedia Commons/Creative Commons Attribution 2.0

“These results indicate that a birth dose of aP vaccine is immunogenic in newborns and significantly narrows the immunity gap between birth and 14 days after receipt of DTaP at 6 or 8 weeks of age, marking the critical period when infants are most vulnerable to severe pertussis infection,” reported Nicholas Wood, PhD, of the National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases in New South Wales, Australia, and his colleagues.

“Administration of the acellular pertussis vaccine at birth has the potential to reduce severe morbidity from Bordetella pertussis infection in the first 3 months of life, especially for infants of mothers who have not received a pertussis vaccine during pregnancy,” the researchers concluded in JAMA Pediatrics.

The researchers enrolled 417 infants from Sydney, Melbourne, Adelaide, and Perth between June 2010 and March 2013 and randomized them to receive either the hepatitis B vaccine alone (n = 205) or the hepatitis B vaccine with a monovalent acellular pertussis vaccine (n = 212) within the first 5 days after birth. The randomization was stratified for mothers’ receipt of the Tdap before pregnancy.

The Centers for Disease Control and Prevention currently recommends all newborns receive the hepatitis B vaccine shortly after birth and that pregnant women receive the Tdap vaccine during each pregnancy. There is not currently a monovalent acellular pertussis vaccine licensed in the United States.

The study infants then received the hexavalent DTaP-Hib-hep B-polio vaccine and the 10-valent pneumococcal conjugate vaccine at 6 weeks, 4 months, and 6 months.

The primary outcome was detectable levels of IgG antibody to pertussis toxin and pertactin at 10 weeks old.

Of the 206 infants receiving the pertussis vaccine at birth, 93% had detectable antibodies to pertussis toxin and pertactin at 10 weeks, compared with 51% of the 193 infants who received only the hepatitis B shot (P less than .001). Geometric mean concentration for pertussis toxin IgG also was four times higher in infants who received the pertussis vaccine at birth.

Adverse events were similar in the two groups both at birth and at 32 weeks, demonstrating that the pertussis birth dose is safe and tolerable.

“More important, in this study, the prevalence of fever after receipt of the birth dose, which can mistakenly be associated with potential sepsis and result in additional investigations in the neonatal period, was similar in both the group that received the aP vaccine at birth and the control group,” the authors reported.

A remaining question is the potential impact of maternal antibodies on protection from pertussis.

“The presence of maternal pertussis antibodies at birth can negatively affect postprimary responses to pertussis, diphtheria, and diphtheria-related CRM197 conjugate vaccines with a variety of infant immunization schedules and vaccines,” the authors noted. “The clinical significance of reductions in pertussis antibody related to maternal interference will require ongoing clinical evaluation, because there are no accepted serologic correlates of protection.”

The research was funded by a Australian National Health and Medical Research Council (NHMRC) grant, and several authors received NHMRC grants. One author also was supported by a Murdoch Children’s Research Institute Career Development Award. GlaxoSmithKline provided the vaccine and conducted the serologic assays. The authors reported having no conflicts of interest.

SOURCE: Wood N et al, JAMA Pediatr. 2018 Sep 10. doi: 10.1001/jamapediatrics.2018.2349.