Factors associated with antiretroviral therapy use among pregnant women in rural and urban settings in Southern Province, Zambia: 2016-2019.

OBJECTIVES: To assess antiretroviral therapy (ART) coverage among pregnant women living with HIV and compare the characteristics of women who received and did not receive ART during pregnancy in Zambia. METHODS: A cross-sectional study was conducted at urban and rural health facilities in Southern Province, Zambia, from 2016 to 2019. Pregnant women living with HIV delivering at study sites were enrolled and administered a questionnaire, and the results of infant diagnostic testing for HIV at birth was documented. RESULTS: About 1184 mother/infant pairs were enrolled. ART coverage was 93.7%. Most women who did not receive ART during pregnancy reported HIV diagnosis at delivery (18.0%) or during pregnancy (57.7%). The primary reported reason for not receiving ART was not wanting to take the drugs. Women who did not receive ART during pregnancy were significantly younger, less likely to have disclosed their HIV-infection status to others, and less likely to have received antenatal care than women who received ART. ART use correlated with higher levels of education in urban but not rural sites. Overall, 1.0% of infants were infected with HIV at birth, including 0.8% of infants born to women who received ART and 4.1% of infants born to women who did not. CONCLUSIONS: Most women received ART according to guidelines, resulting in low perinatal transmission rates of HIV to infants. Efforts to increase ART coverage and prevent vertical transmission should focus on identifying incident HIV infections during pregnancy and strengthening counselling for newly diagnosed pregnant women.

Rapid Generation of Neutralizing Antibody Responses in COVID-19 Patients.

SARS-CoV-2, the virus responsible for COVID-19, is causing a devastating worldwide pandemic, and there is a pressing need to understand the development, specificity, and neutralizing potency of humoral immune responses during acute infection. We report a cross-sectional study of antibody responses to the receptor-binding domain (RBD) of the spike protein and virus neutralization activity in a cohort of 44 hospitalized COVID-19 patients. RBD-specific IgG responses are detectable in all patients 6 days after PCR confirmation. Isotype switching to IgG occurs rapidly, primarily to IgG1 and IgG3. Using a clinical SARS-CoV-2 isolate, neutralizing antibody titers are detectable in all patients by 6 days after PCR confirmation and correlate with RBD-specific binding IgG titers. The RBD-specific binding data were further validated in a clinical setting with 231 PCR-confirmed COVID-19 patient samples. These findings have implications for understanding protective immunity against SARS-CoV-2, therapeutic use of immune plasma, and development of much-needed vaccines.

Rapid generation of neutralizing antibody responses in COVID-19 patients.

SARS-CoV-2 is currently causing a devastating pandemic and there is a pressing need to understand the dynamics, specificity, and neutralizing potency of the humoral immune response during acute infection. Herein, we report the dynamics of antibody responses to the receptor-binding domain (RBD) of the spike protein and virus neutralization activity in 44 COVID-19 patients. RBD-specific IgG responses were detectable in all patients 6 days after PCR confirmation. Using a clinical isolate of SARS-CoV-2, neutralizing antibody titers were also detectable in all patients 6 days after PCR confirmation. The magnitude of RBD-specific IgG binding titers correlated strongly with viral neutralization. In a clinical setting, the initial analysis of the dynamics of RBD-specific IgG titers was corroborated in a larger cohort of PCR-confirmed patients (n=231). These findings have important implications for our understanding of protective immunity against SARS-CoV-2, the use of immune plasma as a therapy, and the development of much-needed vaccines.