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News|Articles|January 24, 2024

COVID-19 vaccine dosing impact on maternal and infant antibodies

A recent study revealed that patients with 3 or more COVID-19 vaccination doses exhibit a significant increase in cord anti-Spike antibody levels compared to those with 2 doses.

Cord anti-Spike (anti-S) antibody levels are increased 10-fold in patients with 3 or more COVID-19 vaccination doses compared to patients with 2 doses, according to a recent study published in JAMA Network Open.

Takeaways

  1. Cord anti-Spike (anti-S) antibody levels are significantly higher (10-fold increase) in patients with 3 or more COVID-19 vaccination doses compared to those with 2 doses, according to a study published in JAMA Network Open.
  1. COVID-19 infection during pregnancy increases the risks of hospitalizations, intensive care unit admission, and mortality. Vaccination during pregnancy is crucial to reduce these risks, and data suggests that it also lowers the risks of maternal morbidity, hospital admission, critical care admission, stillbirth, and neonatal demise.
  1. The COVID-19 vaccine provides anti-S antibodies that can cross the placenta through active transplacental antibody transfer, similar to vaccines for other conditions. However, there is limited data on maternally derived antibodies in infants born preterm.
  1. An ongoing prospective cohort study aimed to determine how the timing of COVID-19 vaccine administration impacts immunity in preterm and full-term infants. The study included participants with at least 2 doses of mRNA-based COVID-19 vaccines, singleton pregnancy, and other specified criteria.
  1. The study, involving 220 participants, revealed that the odds of cesarean delivery and neonatal intensive care unit admission were higher among preterm births. Infants born to mothers who received 3 or more doses of the COVID-19 vaccine had significantly higher antibody levels than those born to mothers who received 2 doses, indicating potential benefits of additional doses for maternal and infant protection.

COVID-19 infection during pregnancy increases the risks of hospitalizations, intensive care unit admission, and mortality. To reduce infection in this population, vaccination is vital.Data has indicated COVID-19 vaccination during pregnancy reduces the risks of maternal morbidity, hospital admission, critical care admission, stillbirth, and neonatal demise.

The COVID-19 vaccine provides anti-S antibodies that are able to cross the placenta through active transplacental antibody transfer, similarly to vaccines against conditions such as influenza. However, there is little data on maternally derived antibodies in infants born preterm.

To determine how the timing of COVID-19 vaccine administration impacts immunity in preterm and full-term infants, investigators conducted an ongoing prospective cohort study. Participants were recruited between February 1, 2021, and January 31, 2023.

Participants included individuals with receipts of at least 2 doses of messenger RNA (mRNA)–based COVID-19 vaccines, singleton pregnancy, no previous COVID-19 infection, paired maternal and cord samples, nondetectable antinucleocapsid antibody, no fetal genetic anomaly, and appropriate infant birth weight, Exclusion criteria included 1 dose or less of the COVID-19 vaccine and receiving a non-mRNA-based vaccine.

Data was available for maternal and cord anti-S IgG, number of vaccine doses, timing of doses, gestational age at delivery, and covariates. Electronical medical records were evaluated for clinical data.

Data on race, gender, ethnicity, insurance status, and body mass index (BMI) were also obtained.Preeclampsia and chronic hypertension diagnoses were defined by American College of Obstetricians and Gynecologists’ criteria and hypertension diagnosis at under 20 weeks’ gestation, respectively. 

Elecsys Anti-SARS-CoV-2 immunoassays (Roche Diagnostics) were used to test paired maternal and infant cord samples. This immunoassay has 99.5% sensitivity and 99.8% specificity.

There were 220 participants included in the final analysis, aged a median 34 years and with a median gravidity of 2 and parity of 0. Of participants, 81.8% were White, 2.3% Black, 11.9% Asian, 0.5% Alaska Native, 6.4% Hispanic, and 92.3% non-Hispanic. Private insurance was reported in 93.2% of participants.

Of deliveries, 36 were preterm and 184 full-term.Median BMI was significantly increased in patients with preterm delivery, as well as rates of pregestational diabetes, preeclampsia, and chronic hypertension. Preterm infants were delivered at a median 35.1 weeks and full-term infants a median 39.5 weeks.

The odds of cesarean delivery and neonatal intensive care unit admission among preterm births were 66.7% and 63.9%, respectively, and the median birth weight was 2437 g. Among full-term infants, these rates were 34.8%, 5.4%, and 3453 g.

Receival of 2 COVID-19 vaccine doses before delivery was reported in 55% of participants and 3 or more in 45%. Of preterm deliveries, 69.4% of patients received 3 or more doses and 30.6% 2 doses. Among full-term deliveries, these rates were 40.2% and 59.8%, respectively.

The unadjusted geometric mean concentration (GMC) for maternal anti-S antibodies was 674 after 2 doses and 8159 after 3 or more doses. For cord anti-S antibodies, these numbers were 1000 and 9992, respectively. 

Decreased cord to maternal antibody ratios were observed among preterm births compared to full-term births, at 1.18 and 1.40, respectively. However, a significant difference was not observed based on preterm vs full-term birth status in adjusted models.

These results indicated 2 or less doses of COVID-19 vaccination may not provide adequate protection for infants. Investigators recommended further research to determineoptimal COVID-19 vaccine dosing for maternal and infant protection.

Reference

Kachikis A, Pike M, Eckert LO, et al. Timing of maternal COVID-19 vaccine and antibody concentrations in infants born preterm. JAMA Netw Open. 2024;7(1):e2352387. doi:10.1001/jamanetworkopen.2023.52387

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