BACKGROUND AND PURPOSE:

• Flannery et al. (JAMA Pediatrics, 2021) assessed the association between maternal and neonatal SARS-CoV-2–specific antibody concentrations

METHODS:

• Cohort study
• Participants
  • Mother/newborn dyads who delivered between April 9 and August 8, 2020
  • Maternal and cord blood sera available
• Study design
  • Women routinely screened for SARS-CoV-2 (1) on hospital admission to labor and delivery or (2) during pregnancy if symptomatic or exposed 
  • IgG and IgM antibodies to the receptor-binding domain of the SARS-CoV-2 spike protein were measured
  • Antibody concentrations and transplacental transfer ratios were analyzed in combination with demographic and clinical data
• Primary outcome
  • Antibody concentrations and transplacental transfer ratios

RESULTS:

• 1471 mother/newborn dyads
  • Median (IQR) age: 32 (28 to 35) years
  • 26.3% Black/non-Hispanic | 51.3% White/non-Hispanic | 11.8% Hispanic | 7.3% Asian, 3.3% other race/ethnicity
• SARS-CoV-2 antibodies detected at time of delivery
  • Maternal sera: 6% (95% CI, 5% to 7%)
  • Cord sera from the pregnancies with positive maternal antibodies: 87% (95% CI, 78% to 93%)
• In cord sera
  • When antibody present, only IgG detected
  • No antibodies detected in cord sera if mother was seronegative
• 11 infants born to seropositive mothers were seronegative
  • Born to mother with IgM only: 45%
  • Born to mothers with significantly lower IgG concentrations: 55%
• Cord blood IgG concentrations were positively correlated with maternal IgG concentrations (P < 0.001)
• Placental transfer ratios of more than 1.0 were observed among women with asymptomatic SARS-CoV-2 infections as well as those with mild, moderate, and severe COVID-19
• Transfer ratios increased with increasing time between onset of maternal infection and delivery

CONCLUSION:

• Neonates born to seropositive mothers had IgG antibodies to SARS-CoV-2
  • Antibody positive cord sera also documented among asymptomatic pregnancies
• Antibody concentrations in cord blood correlated with
  • Maternal antibody concentrations
  • Duration between onset of infection and delivery
• The authors conclude

Our findings demonstrate the potential for maternally derived antibodies to provide neonatal protection from SARS-CoV-2 infection and will help inform both neonatal management guidance and design of vaccine trials during pregnancy

Learn More – Primary Sources:

Assessment of Maternal and Neonatal Cord Blood SARS-CoV-2 Antibodies and Placental Transfer Ratios

Related ObG Topics:

Infants Born to Mothers with COVID-19 Have Detectable Levels of Antibodies

Neonatal Infection: COVID-19 and Risk for Vertical Transmission

Pregnant Women with COVID-19 at Time of Delivery: NYC Cohort Characteristics and Outcomes

Vertical Transmission in Pregnancies with Confirmed COVID-19