Cochrane COVID-19 Study Register
Poon 2021

Relationship between viral load, infection-to-delivery interval and mother-to-child transfer of anti-SARS-CoV-2 antibodies

  1. Study Type
  2. Observational
  1. Study Aim
  2. Transmission
  3. Diagnostic/Prognostic
  1. Study Design
  2. Case series/Case control/Cohort
  1. Intervention Assignment
  2. Not Applicable

Relationship between viral load, infection-to-delivery interval and mother-to-child transfer of anti-SARS-CoV-2 antibodies

Poon LC, Leung BW, Ma T, Yu FN, Kong CW, Lo TK, So PL, Leung WC, Shu W, Cheung KW, Moungmaithong S, Wang CC
Journal article
Report Results
OBJECTIVE: To investigate the association between SARS-CoV-2 viral load and infection-to-delivery interval with maternal and cord sera anti-SARS-CoV-2 IgG antibody levels in pregnant women with active or recovered SARS-CoV-2 infection. METHOD: In this prospective case-series including consecutive pregnant women with laboratory-confirmed SARS-CoV-2 infection between 27 March 2020 and 24 January 2021, we have collected information regarding deep throat saliva or nasopharyngeal swab (NPS) RT-PCR results, serial cycle threshold (Ct) values at and after diagnosis, demographic, clinical and outcome data and neonatal NPS RT-PCR results. Serum antibodies against SARS-CoV-2 were analyzed. Correlation of maternal Ct values, infection-to-delivery interval, infection duration and viral load area under the curve (AUC) with gestation age (GA) at diagnosis, maternal and cord sera IgG concentrations and transfer ratio were evaluated. RESULTS: Twenty consented pregnant women had delivered their babies by 31 January 2021, including 14 women having recovered from COVID-19 and six with active infection. The median GA at clinical manifestation was 32.7 weeks (range 11.9-39.4). The median infection-to-delivery interval and infection duration were 41.5 days (range 2-187) and 10.0 days (range=1-48), respectively. The median GA at delivery was 39.1 weeks (range=32.4-40.7) and the median seroconversion interval was 14 days (range=1-19). Twelve of 13 neonates born to mothers with recovered infection tested positive for IgG. All neonatal NPS samples were reported to be negative for SARS-CoV-2 and all cord sera tested negative for IgM. There was a negative correlation between IgG concentrations in cord and maternal sera with infection-to-delivery interval and a positive correlation between IgG concentrations in maternal sera with viral load AUC. There was also a significant correlation between transfer ratio with viral load AUC. CONCLUSIONS: In recovered pregnant women with COVID-19, anti-SARS-CoV-2 IgG concentrations at delivery increased with viral load during infection and decreased with infection-to-delivery interval. The median transplacental transfer ratio of IgG was 1.3 and this transfer was reduced by high viral load during infection. This article is protected by copyright. All rights reserved