Studies confirm COVID-19 vaccination during pregnancy benefits newborns
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Findings have shown that COVID-19 mRNA vaccines are safe and effective during pregnancy, and evidence also confirms that the benefits of maternal vaccination extend to newborns.
However, despite the track record of the vaccines and the negative health outcomes associated COVID-19 during pregnancy, vaccine uptake among pregnant women has remained lower compared with that of the general population.
A recent analysis showed that pregnant women are motivated to get vaccinated if health care workers explain how immunization benefits their baby. We spoke with experts about the safety of COVID-19 vaccines during pregnancy and the studies showing how maternal vaccination can protect infants.
‘Primum non nocere’
In a study published this year, Goldshtein and colleagues found that rates of preterm birth, all-cause neonatal hospitalization, post-neonatal hospitalization, congenital anomalies and infant mortality were similar between newborns who were and were not exposed to the Pfizer-BioNTech vaccine in utero.
“The two important tenets of medicine are ‘primum non nocere’ and ‘secundum bene facere’ — first do no harm; second, do good,” Mary Jane Minkin, MD, clinical professor in the department of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine, told Healio. “[This study] clearly outlines no harm ... and there are also other studies out there confirming this.”
One such study found that babies exposed to the vaccine during their mothers’ pregnancy did not hinder fetal brain development.
‘Secundum bene facere’
Multiple studies have shown that newborns may benefit from maternal vaccination, fulfilling the “do good” principle to which Minkin alluded.
In one study, Yang and colleagues evaluated levels of anti-spike immunoglobin G (IgG) antibodies in pregnant women who had received at least one dose of either the Moderna, Pfizer-BioNTech or Johnson & Johnson vaccines. Their data showed that being fully vaccinated at any time during pregnancy was associated with the presence of maternal antibodies.
Conti and colleagues studied a contrasting cohort — mothers with COVID-19 — and found that infants had antibodies in their saliva, “which may partly explain why newborns are resistant to SARS-CoV-2 infection,” they said. They also found that antibodies can be transferred via breast milk to newborns.
Despite this seeming benefit of infection, Yang and colleagues discovered that vaccination during the third trimester yielded maternal and umbilical antibody titers comparable to those observed in women with previous SARS-CoV-2 infection. Additionally, they found that receiving a booster shot during the third trimester was associated with an even greater concentration of antibodies than natural infection.
Another study conducted by Kugelman and colleagues supported these findings, specifically regarding the Pfizer-BioNTech vaccine administered during the second trimester. Though both mothers and their babies in this study had humoral responses, newborns had a 2.6-times higher level of antibodies compared with their mothers.
This transfer of antibodies is crucial for protecting the youngest children, Minkin emphasized.
“Newborns are basically immunocompromised; they cannot make antibodies when they are born,” said Minkin, who is also a Healio Women’s Health & OB/GYN Peer Perspective Board Member. “No trials on immunization to kids are going to look at newborns under 6 months old, so getting this vulnerable group antibodies is key.”
Looking past the newborn stage, Shook and colleagues found that 57% of infants aged 6 months whose mothers had been vaccinated during pregnancy had retained antibodies, compared with 8% of those whose mothers were infected with SARS-CoV-2 during pregnancy. Though this study was small, “these findings provide further incentive for pregnant individuals to pursue COVID-19 vaccination,” the researchers wrote.
Importance of vaccination
As data continue to support the benefits of maternal COVID-19 vaccination for newborns, doctors must continue to advocate for vaccination of pregnant women, according to experts.
“There is now good evidence that vaccination is the safest and most effective way for pregnant women to protect themselves and their babies against COVID-19 infection,” Sarah Stock, MD, PhD, a reader in maternal and fetal health and an honorary consultant and subspecialist in maternal and fetal medicine at the University of Edinburgh Usher Institute, told Healio. “If you are at any stage in pregnancy or hoping to become pregnant, I would strongly encourage you to get vaccinated.”
Given these data and the increased risk for pregnancy complications associated with COVID-19, Minkin said it is best for pregnant women to get vaccinated than risk infection.
“All these [studies] demonstrate that maternal vaccination is safer for the mother, but also safer for her newborn, so why not get the vaccination?” she said. “We often don't get the opportunity to take a win-win situation.”
References:
- Conti MG, et al. JAMA Netw Open. 2021;doi:10.1001/jamanetworkopen.2021.32563.
- Fuss TL, et al. Womens Health Issues. 2021;doi:10.1016/j.whi.2021.09.004.
- Goldshtein I, et al. JAMA Pediatr. 2022;doi:10.1001/jamapediatrics.2022.0001.
- Kugelman N, et al. JAMA Pediatr. 2022;doi:10.1001/jamapediatrics.2021.5683.
- Shook LL, et al. JAMA. 2022;doi:10.1001/jama.2022.1206.
- Yang YJ, et al. Obstet Gynecol. 2022;doi:10.1097/AOG.0000000000004693.