BACKGROUND AND PURPOSE:

• Zeng et al. (JAMA, 2020) examined antibody levels in 6 women with confirmed COVID-19, as well as their infants

METHODS:

• Retrospective study
• Setting
  • Zhongnan Hospital of Wuhan University
• Participants
  • 6 hospitalized pregnant women with confirmed COVID-19
  • Testing: Quantitative RT-PCR for SARS-CoV-2
  • Patients delivered February 16 to March 6, 2020
• Study design
  • Maternal samples: Blood collected at delivery
  • Neonatal samples
    • Blood and throat swabs at birth
  • Cytokines and antibodies (IgG and IgM) also tested
  • Performance characteristics of antibody test kits: IgM: 88.2% (sensitivity) and 99.0% (specificity) | IgG: 97.8% (sensitivity) and 97.9% (specificity)

RESULTS:

• 6 mothers tested | All had mild clinical manifestations
  • All delivered via cesarean in the third trimester in negative pressure isolation rooms
  • Infants were isolated from their mothers immediately after delivery
• Infant characteristics
  • All had normal Apgar scores: 1-minute Apgar scores of 8 to 9 | 5-minute Apgar scores of 9 to 10
  • All RT-PCR tests were negative for SARS-CoV-2

Antibody Testing

• All infants had antibodies detected in their serum
• Both IgG and IgM: 2 infants had both IgG and IgM concentrations higher than the reference rage (<10 AU/mL)
  • Infant 1: IgG level = 125.5; IgM level = 39.6 AU/mL
  • Infant 2: IgG level = 113.91; IgM level = 16.25 AU/mL
  • All mothers also had elevated levels of IgG and IgM
• IgG only: 3 infants had elevated IgG levels
  • Infant 1: 75.49 AU/mL
  • Infant 2: 73.19 AU/mL
  • Infant 3: 51.38 AU/mL)
  • All mothers had elevated IgG and 2 also had elevated IgM levels
• Inflammatory cytokine IL-6 was significantly increased in all infants
• Infants asymptomatic (as of March 8, 2020)

CONCLUSION:

• None of the infants born to mothers with COVID-19 had SARS-CoV-2 detected in their serum or throat swab by RT-PCR
  • However, virus-specific antibodies were found
• 2 infants had elevated IgM concentrations
  • “Unexpected” finding as IgG crosses placenta, but, due to size, IgM does not
  • The authors hypothesize that this finding could be due to placenta damage or the infant producing antibodies
  • Infant responding to in-utero infection with antibody production would suggest vertical transmission of SARS-CoV-2
• Some limitations include
  • Small sample size
  • Lack of cord blood, amniotic fluid, and breast milk samples
  • Incomplete information on the outcome of the infants

Learn More – Primary Sources:

Antibodies in Infants Born to Mothers With COVID-19 Pneumonia

Related ObG Topics: