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Timing of Maternal COVID-19 Vaccine and Antibody Concentrations in Infants Born Preterm
Alisa Kachikis1, Mindy Pike1, Linda O Eckert1,2
1Department of Obstetrics and Gynecology, University of Washington, Seattle.
Insights
COVID-19 vaccination in pregnancy, particularly with three or more doses, significantly boosts infant antibody protection. Maternal antibody levels, not gestational age, are key for infant protection against SARS-CoV-2.
Area of Science:
- Immunology
- Maternal-Fetal Medicine
- Vaccinology
Background:
- COVID-19 vaccines administered during pregnancy can confer protection to infants via transplacental antibody transfer.
- Limited data exist on SARS-CoV-2 antibody levels in preterm infants compared to full-term infants concerning maternal vaccination timing.
Purpose of the Study:
- To compare SARS-CoV-2 anti-Spike (anti-S) antibody levels in preterm and full-term infants.
- To evaluate the impact of COVID-19 vaccine dose timing before delivery on these antibody levels.
Main Methods:
- A prospective cohort study involving pregnant individuals and paired maternal-cord blood samples.
- Analysis of anti-Spike (anti-S) antibody levels in relation to vaccine doses and gestational age at delivery.
- Linear regression models adjusted for relevant covariates.
Main Results:
- Receipt of 3 or more COVID-19 vaccine doses before delivery resulted in a 10-fold increase in cord anti-Spike antibody levels compared to 2 doses.
- No significant association was found between preterm delivery and cord anti-Spike antibody levels after adjusting for vaccine timing and dose number.
- Maternal antibody concentration was a more significant factor than gestational age in determining cord antibody levels.
Conclusions:
- COVID-19 vaccination in pregnancy, especially with an increased number of doses, substantially enhances infant antibody levels.
- Vaccine strategies in pregnancy should consider individuals at risk for preterm delivery.
- Maternal antibody levels are a primary determinant of infant protection, underscoring the importance of maternal vaccination.
Importance:
COVID-19 vaccine-derived antibodies in pregnant people may protect infants from severe infection in the first 6 months of life via transplacental antibody transfer. Few data exist on maternally derived SARS-CoV-2 antibodies in preterm compared with full-term infants in association with vaccination timing.
Objective:
To compare SARS-CoV-2 anti-Spike (anti-S) antibody levels in preterm and full-term infants in the context of vaccine dose timing before delivery.
Design, Setting, And Participants:
This prospective cohort study enrolled pregnant individuals and collected paired maternal and cord blood samples at delivery at the University of Washington between February 1, 2021, and January 31, 2023. Participants who had received at least 2 doses of a messenger RNA COVID-19 vaccine before delivery and did not have a history of prior COVID-19 infection or detectable anti-SARS-CoV-2 nucleocapsid antibodies were included.
Exposures:
Timing of the last vaccine dose and preterm or full-term gestational age at delivery.
Main Outcomes And Measures:
Paired maternal and cord samples were tested for anti-S antibody, and linear regression was used to evaluate associations between preterm delivery and anti-S antibody levels. Covariates included timing of last dose, number of doses, insurance status, and immunosuppressing medications.
Results:
A total of 220 participants (median [IQR] age, 34 [32-37] years; 212 [96.4%] female) with 36 preterm and 184 full-term deliveries were studied. Before delivery, 121 persons received 2 vaccine doses and 99 persons received 3 or more vaccine doses. The geometric mean concentration of maternal anti-S antibodies was 674 (95% CI, 577-787) after 2 doses and 8159 (95% CI, 6636-10 032) after 3 or more doses (P < .001). The cord anti-S antibody geometric mean concentration was 1000 (95% CI, 874-1144) after 2 doses and 9992 (95% CI, 8381-11 914) after 3 or more doses (P < .001). After adjustment for vaccine timing and number of doses before delivery, no association was found between preterm delivery and cord anti-S antibody levels (β = 0.44; 95% CI, -0.06 to 0.94).
Conclusions And Relevance:
In this prospective cohort study of pregnant individuals with preterm and full-term deliveries, receipt of 3 or more compared with 2 doses of COVID-19 vaccine before delivery resulted in 10-fold higher cord anti-S antibody levels. Maternal antibody concentration appeared more important than delivery gestational age in determining cord anti-S antibody levels. The number of doses and timing considerations for COVID-19 vaccine in pregnancy should include individuals at risk for preterm delivery.
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