High Antibody Levels Found in New Mother Blood Cords

The American Journal of Obstetrics & Gynecology published a Research Letter - High antibody levels in cord blood from pregnant women vaccinated against COVID-19 - on September 21, 2021.

This minimal study's findings demonstrate transplacental antibody transfer following mRNA COVID-19 vaccination during pregnancy, with 100% of cord blood specimens having high levels of anti-S antibodies.

Given the combination of positive anti-S IgG and negative anti-N IgG, the neonatal antibodies were secondary to the vertical transfer of antibodies from maternal vaccination rather than natural infection.

The moderately high anti-S IgG titers in two women with longer latency between vaccination and delivery suggest that cord blood antibody level may correlate with an interval of time from vaccine administration to delivery.

Further investigation is needed to determine if vaccination in the second half of pregnancy may confer higher levels of antibody transfer than vaccination earlier in pregnancy.

Most guidance on the importance of vaccination during pregnancy stems from concern for pregnancy as a risk factor for severe COVID illness in the mother. Unfortunately, recent data suggests only 16.3% of pregnant women have been vaccinated despite evidence of prenatal vaccine safety.