Vertical Transmission of SARS-CoV-2-Specific Antibodies and Cytokine Profiles in Pregnancy.

Despite intensive characterization of immune responses after COVID-19 infection and vaccination, research examining protective correlates of vertical transmission in pregnancy are limited. Herein, we profiled humoral and cellular characteristics in pregnant women infected or vaccinated at different trimesters and in their corresponding newborns. We noted a significant correlation between Spike S1-specific IgG antibody and its RBD-ACE2 blocking activity in maternal and cord plasma (p<0.001, R>0.90). Blocking activity of S1-specific IgG was significantly higher in pregnant women infected during the 3rd trimester than the 1st and 2nd trimesters. Elevated levels of 28 cytokines/chemokines, mainly pro-inflammatory, were noted in maternal plasma with infection at delivery while cord plasma with maternal infection 2 weeks before delivery exhibited the emergence of anti-inflammatory cytokines. Our data support vertical transmission of protective SARS-CoV-2-specific antibodies. This vertical antibody transmission and the presence of anti-inflammatory cytokines in cord blood may offset adverse outcomes of inflammation in exposed newborns.