Vulnerability in healthcare: from concept to methods insights from three case studies

This manuscript explores the concept of vulnerability in health. Answering the questions: ‘Which populations or individuals are vulnerable? What are the determinants of vulnerability? What methods and approaches are used to study vulnerability in health?', we attempt to provide a comprehensive description of the problem and explore its Public Health implications. After out-lining health vulnerability conceptualization in general terms, we present three case-studies that illustrate vulnerability factors in relation to access to health services or health outcomes. The first study that we present, analysed trends in time and geographical variations in antenatal care uptake, in Mozambique. Sec-ondary data from three national surveys, conducted in 2011, 2015, 2018, were used. Annual trend growth rates of antenatal care coverage were calculated be-tween 2015 and 2018, in each of the surveys design substrata. Primary focus of this study was to investigate the possible impact of the armed conflict, which has plagued the North of the country since 2017, on antenatal care utilization among mothers. Also, factors possibly associated with the outcome ‘attending at least four antenatal visits before pregnancy’ were analysed, using published data from last available survey (2018). The second study presents results of a cross-sectional survey conducted in the Island of Santiago (Cape Verde), to measure the prevalence of asthma, rhinitis and eczema, among resident children aged 6-7 years old, and their possible asso-ciated risk factors. Individual-level exposure-outcomes associations estimated from standard logistic models were compared to school-level associations esti-mated from multilevel logistic models. The third and last study analysed COVID-19 testing rates among children living in five districts of the Lisbon metropolitan area (Portugal). Primary focus of this study was to investigate dif-ferences in access to the health system, between immigrant and non-immigrant children, while also taking into account other factors potentially associated with the likelihood of accessing or not at least one test and number of tests performed in mean, during the pandemic period. With these three studies, we aim to report, in different contexts, how individual and/or community-level vulnerability factors are closely linked to health out-comes, affecting both access to care and prevalence rates of specific diseases. Although there is a large body of literature on this topic, new approaches to re-search, based on multidisciplinary design and new methods of analysis, could lead to new knowledge, with beneficial implications for health system planning.