COVID-19 Vaccination During Pregnancy Produces Durable Antibodies in Young Infants
Key findings
- This study compared the persistence of maternal antibodies against SARS-CoV-2 in 77 infants of women who were vaccinated between 20 and 32 weeks' gestation and 12 infants whose mothers had symptomatic SARS-CoV-2 infection during the same timeframe
- Serum samples from infants whose mothers were infected were collected at age six months; samples from infants whose mothers were vaccinated were collected at age two months (n=49) or age six months (n=28)
- At age two months, 98% of infants born to vaccinated mothers had detectable anti–Spike protein immunoglobulin G
- At age six months, anti-S IgG was detectable in 57% of infants born to vaccinated mothers vs. 8% of infants born to infected mothers (P=0.005)
- These findings are additional evidence of the benefit of COVID-19 vaccination for pregnant individuals
COVID-19 vaccination during pregnancy generates antibodies in the maternal circulation that can cross the placenta and protect the newborn and infant from COVID-19. At delivery, titers of anti–Spike protein immunoglobulin G (anti-S IgG) in the umbilical cord are highest if the mother was vaccinated in the late second or early third trimester.
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Massachusetts General Hospital researchers have determined that infants born to mothers vaccinated against COVID-19 during pregnancy are more likely to have persistent anti-S antibodies at six months of age than infants born to mothers who became infected with SARS-CoV-2 during pregnancy.
Lydia L. Shook, MD, and Andrea G. Edlow, MD, MSc, investigators in the Vincent Center for Reproductive Biology and maternal–fetal medicine specialists in the Department of Obstetrics and Gynecology, and colleagues report in a research letter in JAMA.
Methods
An earlier prospective study at Mass General and Brigham and Women's Hospital involved patients who received an mRNA COVID-19 vaccine between 20 and 32 weeks gestation or had symptomatic SARS-CoV-2 infection during the same timeframe. Matched maternal and umbilical cord serum samples were collected at delivery.
This follow-up study, conducted between July 21 and October 22, 2021, analyzed serum samples from:
- 77 infants of mothers who had been vaccinated—49 samples collected at age two months; 28 samples collected at age six months
- 12 infants of mothers who had symptomatic SARS-CoV-2 infection during pregnancy—all samples collected at age six months
Results
- At two months, 98% of infants (all born to vaccinated mothers) had detectable anti-S IgG
- At six months, anti-S IgG was detectable in 57% of infants born to vaccinated mothers vs. 8% of infants born to infected mothers (P=0.005)
Why It Matters
COVID-19 infections among infants account for a disproportionate burden of pediatric SARS-CoV-2–associated morbidity, and COVID-19 vaccines are not currently planned for infants younger than six months. The exact antibody titer that protects against COVID-19 in infants is unknown, but these findings provide further rationale for recommending COVID-19 vaccination to pregnant individuals.
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