Conectar
The study aim was to evaluate vaccine effectiveness (VE) of COVID-19 vaccines in preventing symptomatic COVID-19 among healthcare workers (HCWs) in Zambia. We sought to answer the question, ‘What is the vaccine effectiveness of a complete schedule of the SARS-CoV-2 vaccine in preventing symptomatic COVID-19 among HCWs in Zambia?’
We conducted a test-negative case–control study among HCWs across different levels of health facilities in Zambia offering point of care testing for COVID-19 from May 2021 to March 2022.
1767 participants entered the study and completed it. Cases were HCWs with laboratory-confirmed SARS-CoV-2 and controls were HCWs who tested SARS-CoV-2 negative. Consented HCWs with documented history of vaccination for COVID-19 (vaccinated HCWs only) were included in the study. HCWs with unknown test results and unknown vaccination status, were excluded.
The primary outcome was VE among symptomatic HCWs. Secondary outcomes were VE by: SARS-CoV-2 variant strains based on the predominant variant circulating in Zambia (Delta during May 2021 to November 2021 and Omicron during December 2021 to March 2022), duration since vaccination and vaccine product.
We recruited 1145 symptomatic HCWs. The median age was 30 years (IQR: 26–38) and 789 (68.9%) were women. Two hundred and eighty-two (24.6%) were fully vaccinated. The median time to full vaccination was 102 days (IQR: 56–144). VE against symptomatic SARS-CoV-2 infection was 72.7% (95% CI: 61.9% to 80.7%) for fully vaccinated participants. VE was 79.4% (95% CI: 58.2% to 90.7%) during the Delta period and 37.5% (95% CI: –7.0% to 63.3%) during the Omicron period.
COVID-19 vaccines were effective in reducing symptomatic SARS-CoV-2 among Zambian HCWs when the Delta variant was circulating but not when Omicron was circulating. This could be related to immune evasive characteristics and/or waning immunity. These findings support accelerating COVID-19 booster dosing with bivalent vaccines as part of the vaccination programme to reduce COVID-19 in Zambia.
by Katayi Mwila-Kazimbaya, Samuel Bosomprah, Obvious Nchimunya Chilyabanyama, Caroline Cleopatra Chisenga, Mwelwa Chibuye, Natasha Makabilo Laban, Michelo Simuyandi, Bert Huffer Jr, Miren Iturriza-Gomara, Robert K. M. Choy, Roma Chilengi
BackgroundRotavirus gastroenteritis remains a leading cause of morbidity and mortality despite the introduction of vaccines. Research shows there are several factors contributing to the reduced efficacy of rotavirus vaccines in low- and middle-income settings. Proposed factors include environmental enteric dysfunction (EED), malnutrition, and immune dysfunction. This study aimed to assess the effect of these factors on vaccine responses using a machine learning lasso approach.
MethodsSerum samples from two rotavirus clinical trials (CVIA 066 n = 99 and CVIA 061 n = 124) were assessed for 11 analytes using the novel Micronutrient and EED Assessment Tool (MEEDAT) multiplex ELISA. Immune responses to oral rotavirus vaccines (Rotarix, Rotavac, and Rotavac 5D) as well as a parenteral rotavirus vaccine (trivalent P2-VP8) were also measured and machine learning using the lasso approach was then applied to investigate any associations between immune responses and environmental enteric dysfunction, systemic inflammation, and growth hormone resistance biomarkers.
ResultsBoth oral and parenteral rotavirus vaccine responses were negatively associated with retinol binding protein 4 (RBP4), albeit only weakly for oral vaccines. The parenteral vaccine responses were positively associated with thyroglobulin (Tg) and histidine-rich protein 2 (HRP2) for all three serotypes (P8, P6 and P4), whilst intestinal fatty acid binding protein (I-FABP) was negatively associated with P6 and P4, but not P8, and soluble transferrin receptor (sTfR) was positively associated with P6 only.
ConclusionMEEDAT successfully measured biomarkers of growth, systemic inflammation, and EED in infants undergoing vaccination, with RBP4 being the only analyte associated with both oral and parenteral rotavirus vaccine responses. Tg and HRP2 were associated with responses to all three serotypes in the parenteral vaccine, while I-FABP and sTfR results indicated possible strain specific immune responses to parenteral immunization.
FreshRSS 