Immune Response to SARS-CoV-2 in Vaccine-naive Pregnant Women: Assessment of IgG and IgA Antibody Profile at Delivery and 42 Days Postpartum.

This prospective cohort study assessed the SARS-CoV-2 IgG and IgA Ab profiles at delivery and 42 d postpartum in unvaccinated SARS-CoV-2-positive pregnant women and determined the association with the timing and the clinical course of the infection. A total of 387 vaccine-naive women with confirmed SARS-CoV-2 infection during pregnancy were included. IgG and IgA Abs were detected in maternal blood at delivery and 42 d postpartum using ELISA kits. The relationships between Ab detection and value and clinical features, including the timing of the infection, were analyzed using univariate and multivariate logistic and linear regression models. The mean gestational age at infection was 31 4/7 wk of pregnancy. Symptoms of SARS-CoV-2 infection were present in 88.1% of women. IgG and IgA Abs were detected in 45.7 and 58.9% at delivery, respectively, increasing to 72.7 and 76.8% at 42 d postpartum. Detection of IgG and IgA Abs in maternal blood at delivery was independently associated with symptomatic infection (adjusted odds ratio [OR] 3.13, 95% confidence interval (CI): 1.47-6.69 and adjusted OR 3.62, 95% CI: 1.8-7.26, respectively), but not with the time from positive swab to delivery or gestational age at positive swab. Detection of Abs at 42 d postpartum was also strongly associated with the detection of Abs at delivery (OR 29.97, 95% CI: 10.11-88.82 for IgG and OR 13.09, 95% CI: 6.37-26.9 for IgA). Vaccine-naive pregnant women exhibit a significant and durable immune response to SARS-CoV-2, which is more pronounced in symptomatic women but independent of gestational age at diagnosis or the diagnosis-to-delivery interval.