Hybrid Immunity to SARS-CoV-2 During Pregnancy Provides More Durable Infant Antibody Responses Compared to Natural Infection Alone.

BACKGROUND: Hybrid immunity (infection plus vaccination) may increase maternally derived SARS-CoV-2 antibody responses and durability versus infection alone. METHODS: Prospective cohort of pregnant participants with prior SARS-CoV-2 infection (anti-nucleocapsid IgG, RT-PCR, or antigen positive) and their infants had blood collected in pregnancy, at delivery/birth, and postpartum tested for anti-spike (anti-S) IgG and neutralizing antibodies (neutAb). RESULTS: Among 107 participants at enrollment, 40% were unvaccinated and 60% were vaccinated (received ≥1 dose); 102 had previous SARS-CoV-2 infection in pregnancy (median, 19 weeks' gestation); 5 were diagnosed just prior to pregnancy (median, 8 weeks). At delivery, fewer unvaccinated participants (87% anti-S IgG+, 86% neutAb) and their infants (86% anti-S IgG+, 75% neutAb) had anti-S IgG+ or neutAb compared to vaccinated participants and their infants (100%, P ≤ .01 for all). By 3-6 months postpartum, 50% of infants of unvaccinated participants were anti-S IgG+ and 14% had neutAb, versus 100% among infants of vaccinated participants (all P < .01), with lower median antibody responses (anti-S IgG log10 1.95 vs 3.84 AU/mL, P < .01; neutAb log10 1:1.34 vs 1:3.20, P = .11). CONCLUSIONS: In pregnant people with prior SARS-CoV-2, vaccination before delivery provided more durable maternally derived antibody responses than infection alone in infants through 6 months.

Severe acute respiratory syndrome coronavirus 2 seroprevalence and longitudinal antibody response following natural infection in pregnancy: A prospective cohort study.

BACKGROUND: Antenatal care provides unique opportunities to assess severe acute respiratory syndrome coronavirus 2 seroprevalence and antibody response duration after natural infection detected during pregnancy; transplacental antibody transfer may inform peripartum and neonatal protection. We estimated seroprevalence and durability of antibodies from natural infection (anti-nucleocapsid immunoglobulin G) among pregnant people, and evaluated transplacental transfer efficiency. OBJECTIVE AND DESIGN: We conducted a cross-sectional study to measure severe acute respiratory syndrome coronavirus 2 seroprevalence, and a prospective cohort study to longitudinally measure anti-nucleocapsid immunoglobulin G responses and transplacental transfer of maternally derived anti-nucleocapsid antibodies. METHODS: We screened pregnant people for the seroprevalence study between 9 December 2020 and 19 June 2021 for anti-nucleocapsid immunoglobulin G in Seattle, Washington. We enrolled anti-nucleocapsid immunoglobulin G positive people from the seroprevalence study or identified through medical records with positive reverse transcription polymerase chain reaction or antigen positive results in a prospective cohort between 9 December 2020 and 9 August 2022. RESULTS: In the cross-sectional study (N = 1284), 5% (N = 65) tested severe acute respiratory syndrome coronavirus 2 anti-nucleocapsid immunoglobulin G positive, including 39 (60%) without prior positive reverse transcription polymerase chain reaction results and 42 (65%) without symptoms. In the prospective cohort study (N = 107 total; N = 65 from the seroprevalence study), 86 (N = 80%) had anti-nucleocapsid immunoglobulin G positive results during pregnancy. Among 63 participants with delivery samples and prior anti-nucleocapsid positive results, 29 (46%) were anti-nucleocapsid immunoglobulin G negative by delivery. Of 34 remaining anti-nucleocapsid immunoglobulin G positive at delivery with paired cord blood, 19 (56%) had efficient transplacental anti-nucleocapsid immunoglobulin G antibody transfer. Median time from first anti-nucleocapsid immunoglobulin G positive to below positive antibody threshold was 19 weeks and did not differ by prior positive reverse transcription polymerase chain reaction status. CONCLUSIONS: Maternally derived severe acute respiratory syndrome coronavirus 2 antibodies to natural infection may wane before delivery. Vaccines are recommended for pregnant persons to reduce severe illness and confer protection to infants.