HBV vaccine birth dose not tied to premature babies’ lung disease risk
Researchers reviewed extremely preterm births between 2017-2020
Babies born extremely prematurely who were given a dose of the hepatitis B virus (HBV) vaccine within a day of being born were not at an increased risk of developing bronchopulmonary dysplasia (BPD), a serious lung disease that affects premature newborns, relative to unvaccinated babies, a recent Australian report indicates.
The findings lend support for existing World Health Organization (WHO) recommendations that all newborns receive a birth dose of the HBV vaccine.
“This study identified no evidence of an increased risk of BPD in preterm infants who received the HBV vaccine compared to those who didn’t,” Hannah Morgan, a PhD candidate at Murdoch Children’s Research Institute in Australia and the study’s first author, said in a news release. “These findings could help streamline decision-making in neonatal care units across the country.”
The study, “Hepatitis B vaccination of preterm infants and risk of bronchopulmonary dysplasia: a cohort study, Australia,” was published in the Bulletin of the World Health Organization.
HBV is a viral cause of hepatitis, or inflammation of the liver. While some HBV infections are acute and clear up on their own without causing significant health problems, other people develop chronic infections that drive serious liver damage in the long term. The virus is spread through contact with infected body fluids like blood, saliva, semen, or vaginal fluids. It can also be passed from mother to child during pregnancy or in childbirth.
Babies infected with HBV during childbirth or shortly thereafter are 90% more likely to develop a chronic infection relative to those infected later, data indicate. The best way to prevent HBV infection and its potentially serious consequences is to get vaccinated against it.
WHO recommends that all infants receive the first dose of an HBV vaccine within 24 hours of birth, called a birth dose, regardless of their size. The guidelines also apply to infants born prematurely, which is usually considered less than 37 gestation weeks, or weeks of pregnancy.
Assessing HBV vaccination, BPD link
Australian health authorities have issued similar recommendations. However, concern about birth doses in premature infants were raised after Australian researchers identified a link between certain immune cell activity and the development of BPD in infants born extremely preterm, that is, less than 29 weeks gestation. This immune profile was also associated with early HBV vaccination.
BPD is a serious lung condition that affects premature babies, especially the earlier they’re born. It causes damage to the alveoli, or tiny air sacs in the lungs, leading to breathing problems, and can give rise to heart failure and developmental delays.
Given current Australian guidelines on birth dosing infants, better understanding the possible link between HBV vaccination and BPD in preterm infants became “a national priority,” according to the researchers, who examined outcomes from all the babies born extremely preterm between 2017-2020 in Victoria, a state in Australia.
The data were obtained from the state’s Vaccine Safety Health Link, which couples immunization and health outcome datasets in order to inform public health recommendations on vaccines.
“The Vaccine Safety Health Link … has proven to be a powerful tool that continues to help us answer ongoing questions in vaccine research,” Morgan said. “Victoria is unique in that we can link anonymous, statewide data on vaccination with birth records, perinatal and the outcomes of babies, ensuring the latest safety information can be provided.”
Among 818 extremely preterm babies, 306 received a birth dose of the HBV vaccine. By age 2, 96% of the babies had received at least one dose.
Overall, a birth dose of the HBV vaccine wasn’t associated with an increased risk of BPD, with 50.7% of vaccinated babies and 61.9% of unvaccinated babies developing the lung condition. A small proportion of vaccinated (2.3%) and unvaccinated (2.7%) babies died within the first three months of life, with no increased mortality risk associated with the birth dose.
The findings held even when the analysis was adjusted for other potentially influential factors, but not all the factors could be accounted for, including the babies’ sex, differences in vaccination practices across clinics, and clinical decision making for unwell babies, the researchers said.
Still, the study indicates “there is no evidence of any additional harm or risk of bronchopulmonary dysplasia using the birth dose for these neonates,” the researchers wrote. “Although only a large multicenter randomized controlled trial can definitively account for all potential confounding, our findings provide support to existing WHO recommendations to immunize all infants against HBV within 24 hours of birth.”
The study was supported by programs funded by the Victoria state government.
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