Hybrid Immunity to SARS-CoV-2 During Pregnancy Provides More Durable Infant Antibody Responses Compared to Natural Infection Alone.

Background: Hybrid immunity (infection plus vaccination) may increase maternally derived SARS-CoV-2 antibody responses and durability versus infection alone.

Methods: Prospective cohort of pregnant participants with prior SARS-CoV-2 infection (anti-nucleocapsid IgG, RT-PCR, or antigen positive) and their infants had blood collected in pregnancy, at delivery/birth, and postpartum tested for anti-spike (anti-S) IgG and neutralizing antibodies (neutAb).

Results: Among 107 participants at enrollment, 40% were unvaccinated and 60% were vaccinated (received ≥1 dose); 102 had previous SARS-CoV-2 infection in pregnancy (median, 19 weeks' gestation); 5 were diagnosed just prior to pregnancy (median, 8 weeks).

A population-based study of primary human herpesvirus 6 infection.

Background: Serologic studies indicate that human herpesvirus 6 (HHV-6) infects 90 percent of children by two years of age. Little is known about the acquisition, virologic course, and clinical manifestations of HHV-6 infection.

Methods: We prospectively studied a cohort of 277 children from birth through the first two years of life to define the pattern of acquisition of HHV-6.