Browsing by Author "Kwatra, Gaurav"

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    Prevalence of Group B Streptococcus colonization and serotype distribution among pregnant women in South Asian and African countries
    (University of the Witwatersrand, Johannesburg, 2024) Kwatra, Gaurav; Madhi, Shabir A.
    Background: Recto-vaginal Group B Streptococcus (GBS) colonization in pregnant women at the time of labour is the major risk-factor for developing invasive GBS disease within 7 days of age (early onset disease; EOD). We investigated prevalence of GBS recto-vaginal colonization at the time of labour among pregnant women and vertical transmission to their newborns across six African and two south-Asian countries. Methods: This multi-country prospective, observational cross-sectional study was undertaken in six African [(Ethiopia (Adama city), Kenya (Kilifi), Mozambique (Manhica), Nigeria (Gwagwalada), Mali (Bamako) and South Africa (Johannesburg) and two Southeast Asian countries (Bangladesh (Mirzapur) and India (Vellore)]. Inclusion criteria included pregnant women 18 to 45 years of age, delivery at ≥37 weeks gestation and documented to be HIV-uninfected prior to study-enrolment. Lower vaginal swabs, rectal swabs and urine were collected from the mothers and separate skin surface swabs of the umbilicus, outer ear and axillary fold; and rectal and throat swabs were obtained from the newborn for GBS culture. Standardized sampling and culture using direct plating and selective broth media for detection of GBS colonization in the mother-newborn dyads was undertaken across the sites. Serotyping of GBS isolates was done in South Africa. Results: Overall, 6,922 pregnant women were enrolled from January 10th , 2016 to December 11th , 2018. Of 6922 women who were enrolled, 6514 (94.1%; 759 to 892 per site) were included in the analysis. Overall, the prevalence of maternal GBS colonization was 24.1% (95%CI 23.1- 25.2; 1572/6514) being highest in Mali (41.1%, 95%CI: 37.7-44.6; 314/764) and lowest in Ethiopia (11.6%, 95%CI:9.5-14.1; 88/759). The overall rate of vertical transmission of GBS was 72.3% (95%CI 70.0-74.4; 1132/1566); being highest in Mozambique (79.2%, 95%CI 73.3-84.2); 168/212) and lowest in Bangladesh (55.8%, 95%CI 47.5-63.8; 77/138). The five most common GBS colonizing serotypes were Ia (37.3%; 586/1572), V (28.5%; 448/1572), III (25.1%; 394/1572), II (9.2%; 144/1572) and Ib (6.5%; 102/1572). There was geographic variability in serotype proportion distribution. Serotype VII was the third most common serotype in India (8.5%, n=15/176) and serotype VI was mainly identified in Bangladesh (5.8%) and India (5.7%). Conclusion: Our study reported high prevalence of GBS colonization in most settings, with some geographic variability even within African countries. Our findings suggests that there is likely to be a significant burden of EOD across the study sites. Post-licensure vaccine effectiveness studies should also focus on maternal GBS serotype distribution as non-vaccine serotype replacement could occur due to vaccine immune pressure
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    T‑cell responses to ancestral SARS‑CoV‑2 and Omicron variant among unvaccinated pregnant and postpartum women living with and without HIV in South Africa
    (Nature Research, 2024-09) Madhi, Shabir A.; McMahon, William C.; Kwatra, Gaurav; Izu, Alane; Jones, Stephanie A.; Mbele, Nkululeko J.; Jafta, Nwabisa; Lala, Rushil; Shalekof, Sharon; Tiemessen, Caroline T.; Nunes, Marta C.
    SARS-CoV-2 cell-mediated immunity remains understudied during pregnancy in unvaccinated Black African women living with HIV (WLWH) from low- and middle-income countries. We investigated SARS-CoV-2-specifc T-cell responses 1 month following infection in 24 HIV-uninfected women and 15 WLWH at any stage during pregnancy or postpartum. The full-length spike (FLS) glycoprotein and nucleocapsid (N) protein of wild-type (WT) SARS-CoV-2, as well as mutated spike protein regions found in the Omicron variant (B.1.1.529) were targeted by flow cytometry. WT-specific CD4+and CD8+T cells elicited similar FLS- and N-specific responses in HIV-uninfected women and WLWH. SARS-CoV 2-specifc T-lymphocytes were predominantly TNF-α monofunctional in pregnant and postpartum women living with and without HIV, with fever cells producing either IFN-γ or IL-2. Furthermore, T-cell responses were unaffected by Omicron-specific spike mutations as similar responses between Omicron and the ancestral virus were detected for CD4+ and CD8+ T cells. Our results collectively demonstrate comparable T-cell responses between WLWH on antiretroviral therapy and HIV-uninfected pregnant and postpartum women who were naïve to Covid-19 vaccination. Additionally, we show that T cells from women infected with the ancestral virus, Beta variant (B.1.351), or Delta variant (B.1.617.2) can cross-recognize Omicron, suggesting an overall preservation of T-cell immunity.