RESUMO
Background: Vaccination is an important public health intervention, but not everyone benefits equally. Biological, social and structural factors render some communities vulnerable and unable to secure optimal health benefits from vaccination programmes. This drives health inequity and undermines wider vaccine impact by allowing the persistence of non-immune communities as foci for recurrent disease outbreaks. The NIHR Global Health Research Group on Vaccines for vulnerable people in Africa (VAnguard) aims to understand how biological, social, and structural factors interact to impair vaccine impact in vulnerable African communities. Methods: The VAnguard project will be implemented through three thematic work packages (1-3) and four cross-cutting work packages (4-7). Work package 1 will investigate the biological drivers and mechanisms of population differences in vaccine responses. Work package 2 will support the understanding of how structural, social and biological determinants of vaccine response interrelate to determine vaccine impact. Work package 3 will synthesise data and lead analyses to develop, model and test community-based integrated strategies to optimise vaccine access, uptake and effectiveness. Work package 4 will plan and implement field investigations (community survey and qualitative studies (with support of work package 2) to explore structural, social & biological determinants impairing vaccine impact. Work package 5 will collaborate with work packages 1-4, to engage communities in designing interventions that aim to directly optimise vaccine impact through a process of co-learning and co-creation between them and the researchers. Work package 6 will build capacity for, and a culture of, consultative, collaborative multidisciplinary vaccine research in East Africa. Work package 7 will support the overall project management and governance. Following the project inception on the 1 st of September 2022, project launch was held in November 2022. Conclusion: Results from this project will contribute to the development of integrated strategies that will optimise vaccine benefits and drive health equity.
Vaccination is an important public health intervention but not everyone benefits equally. Some vaccines give weaker protection in people from rural, tropical settings than in those from high income settings. Some new vaccines, under development, also elicit weaker responses in people living in low-income, rural settings. The biological reasons for this are not fully understood. Also, some people benefit less from vaccines for socioeconomic reasons, such as the social context of the communities they live in, including limited access to accurate information to aid vaccine choices. Social and biological factors can interact to make communities "vulnerable" in terms of vaccine impact. This needs to be addressed to promote health equity, but also to secure maximum global benefit from vaccines. VAnguard's goal is to understand how biological, social, and structural factors interact to impair vaccine impact in vulnerable African communities, and to develop integrated strategies to optimise vaccine benefits and drive health equity. First, we shall work with national stakeholders (such as Ministries of Health, and vaccine-related non-governmental organisations), review literature, and work on samples from previous studies, to identify Ugandan and Kenyan communities likely to have the most difficulty in getting the best out of vaccination programmes ("vulnerable communities"). Then, with stakeholders and communities, we shall co-design the VAnguard Community Study, and implement it to investigate in detail which biological and social factors most influence vaccine impact in vulnerable communities. Data and economic modellers will study the results to identify which factors could usefully be modified, and we shall work with the communities to explore ways in which this could be done. Hence, we shall co-develop strategies which national stakeholders may be able to implement straight away, or which can be tested in future studies.
RESUMO
Background: There are limited data on the immunogenicity of coronavirus disease 2019 (COVID-19) vaccines in African populations. Here we report the immunogenicity and safety of the ChAdOx1 nCoV-19 (AZD1222) vaccine from a phase 1/2 single-blind, randomised, controlled trial among adults in Kenya conducted as part of the early studies assessing vaccine performance in different geographical settings to inform Emergency Use Authorisation. Methods: We recruited and randomly assigned (1:1) 400 healthy adults aged ≥18 years in Kenya to receive ChAdOx1 nCoV-19 or control rabies vaccine, each as a two-dose schedule with a 3-month interval. The co-primary outcomes were safety, and immunogenicity assessed using total IgG enzyme-linked immunosorbent assay (ELISA) against SARS-CoV-2 spike protein 28 days after the second vaccination. Results: Between 28 th October 2020 and 19 th August 2021, 400 participants were enrolled and assigned to receive ChAdOx1 nCoV-19 (n=200) or rabies vaccine (n=200). Local and systemic adverse events were self-limiting and mild or moderate in nature. Three serious adverse events were reported but these were deemed unrelated to vaccination. The geometric mean anti-spike IgG titres 28 days after second dose vaccination were higher in the ChAdOx1 group (2773 ELISA units [EU], 95% CI 2447, 3142) than in the rabies vaccine group (61 EU, 95% CI 45, 81) and persisted over the 12 months follow-up. We did not identify any symptomatic infections or hospital admissions with respiratory illness and so vaccine efficacy against clinically apparent infection could not be measured. Vaccine efficacy against asymptomatic SARS-CoV-2 infection was 38.4% (95% CI -26.8%, 70.1%; p=0.188). Conclusions: The safety, immunogenicity and efficacy against asymptomatic infection of ChAdOx1 nCoV-19 among Kenyan adults was similar to that observed elsewhere in the world, but efficacy against symptomatic infection or severe disease could not be measured in this cohort. Pan-African Clinical Trials Registration: PACTR202005681895696 (11/05/2020).