Maternal SARS-CoV-2 IgG provides limited protection for their infants

Abstract

At present, there are still many ambiguous reports about the perinatal infection of infants born to mothers infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1-3. The dynamic characteristics of infantile serum antibodies born to mother with SARS-CoV-2 has not been well described4-6. In this study, we analyzed the seroconversion of 27 newborns born to 26 pregnant women infected with SARS-CoV-2. The SARS-CoV-2 IgG positive rate of parturients was 80.8%, and half of their infants obtained maternal IgG. IgG transfer rates were 18.8% and 81.8% in those infants whose mother infected less and more than 2 weeks before delivery respectively. In the first two months of life, the IgG level of infants dropped sharply to one tenth of that at birth. The IgM was confirmed positive in 53.8% of mothers and negative in all infants. These results suggest that maternal IgG has limited protection for infants, which may help us to improve vaccination strategies in future.