Vertical transmission and humoral immune response following maternal infection with SARS-CoV-2: a prospective multicenter cohort study.

OBJECTIVE: To explore maternal humoral immune responses to SARS-CoV-2 infection and the rate of vertical transmission. METHODS: A prospective cohort study was conducted at two university-affiliated medical centers in Israel. Women positive for SARS-CoV-2 reverse-transcription-polymerase-chain-reaction (RT-PCR) test during pregnancy were enrolled just prior to delivery. Levels of anti-SARS-CoV-2 spike-IgM, spike IgG, and nucleocapsid IgG were tested in maternal and cord blood at delivery, and neonatal nasopharyngeal swabs were subjected to PCR testing. The primary endpoint was the rate of vertical transmission, defined as either positive neonatal IgM or positive neonatal PCR. RESULTS: Among 72 women, 36 (50%), 39 (54%) and 30 (42%) were positive for anti-spike-IgM, anti-spike-IgG, and anti-nucleocapsid-IgG, respectively. Among 36 neonates in which nasopharyngeal swabs were taken, one neonate (3%, 95% confidence interval 0.1-15%) had a positive PCR result. IgM was not detected in cord blood. Seven neonates had positive IgG antibodies while their mothers were seronegative for the same IgG. Anti-nucleocapsid-IgG and anti-spike-IgG were detected in 25/30 (83%) and in 33/39 (85%) of neonates of seropositive mothers, respectively. According to the serology test results during delivery with respect to the time of SARS-CoV-2 infection, the highest rate of positive maternal serology tests was 8 to 12 weeks post-infection (89% anti-spike IgG, 78% anti-spike IgM, and 67% anti-nucleocapsid IgG). Thereafter, the rate of positive serology tests declined gradually; at 20 weeks post-infection, only anti-spike IgG was detected in 33 to 50%. DISCUSSION: The rate of vertical transmission of SARS-CoV-2 was at least 3% (95% confidence interval 0.1-15%). Vaccination should be considered no later than 3 months post-infection in pregnant women due to a decline in antibody levels.

Neonatal SARS-CoV-2 Infections in Breastfeeding Mothers.

OBJECTIVES: To assess infection rates predischarge and postdischarge in breast milk-fed newborns with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive mothers who were separated postdelivery from their mothers and discharged from the hospital. Also, we aim to evaluate breastfeeding rates predischarge and postdischarge. METHODS: Nasopharyngeal swabs for SARS-CoV-2 were obtained from symptomatic and high-risk women in the delivery room. Mothers with positive SARS-CoV-2 test results were separated from the newborns. Newborns were screened within 48 hours of delivery, and anti-infectious guidelines were imparted to the mothers before discharge. Rescreening took place ≥14 days postdischarge. Data regarding SARS-CoV-2-positive household members and breastfeeding were obtained by follow-up phone calls. RESULTS: A total of 73 newborns of SARS-CoV-2-positive mothers were born in Israel during the ∼3-month period under study. Overall, 55 participated in this study. All neonates tested negative for the virus postdelivery. A total 74.5% of the neonates were fed unpasteurized expressed breast milk during the postpartum separation until discharge. Eighty-nine percent of the neonates were discharged from the hospital after their mothers were instructed in anti-infection measures. In 40% of the households, there were additional SARS-CoV-2-positive residents. A total of 85% of the newborns were breastfed postdischarge. Results for all 60% of the newborns retested for SARS-CoV-2 postdischarge were negative. CONCLUSIONS: No viral infection was identified in neonates born to and separated from their SARS-CoV-2-positive mothers at birth and subsequently fed unpasteurized breast milk. All infants breastfed at home remained SARS-CoV-2 negative. These findings may provide insights regarding the redundancy of postpartum mother-newborn separation in SARS-CoV-2-positive women and, assuming precautions are adhered to, support the safety of breast milk.