Do low TB prevalence and lack of BCG Vaccinations Contribute to Emergence Multisystem Inflammatory Syndrome in Children?

BackgroundEmergence of new multisystem inflammatory syndrome in children (MIS-C) is thought to be associated with COVID-19 pandemic. Covid-19 morbidity and mortality variances among countries have been suggested by previous works to be influenced by BCG and previous latent TB infection (which is reflected by TB prevalence) possibly through inducing heterogeneous immunity against SARS-CoV-2. AimTo examine influence of BCG status and TB prevalence on variances among countries which report new multisystem inflammatory syndrome in children (MIS-C). MethodsWe choose all countries which report MIS-C till 23/6/2020, number of cases for each 10 million inhabitants was examined among 3 categories of countries classified according to BCG program status. TB prevalence, MIS-C no. / 10 million (M) population and Covid-19 deaths/M are taken as markers. Receiver operation characteristic - (ROC) curve, with some relative indicators such as (sensitivity and specificity rates), estimation area of trade - off between sensitivity and specificity, and cutoff points are used with different studied markers for discriminating different three pairs of countries (which have different BCG practices). ResultsBCG vaccinations and high TB prevalence are found to be associated with decrease MIS-C no. and COVID-19 deaths ConclusionsFindings might explain variances in MIS-C incidence and in COVID-19 mortality among countries worldwide. Further studies to confirm this relation and to confirm possible similar relations in Kawasaki disease(KD) in previous epidemics is recommended. What is Known- Although the etiology for KD remains unknown, available evidence supports the hypothesis that the pathogenesis is closely associated with dysregulation of immune responses to an infectious agent. - BCG and / or Latent TB have heterogeneous beneficial effects. What is NewOur study shows that TB prevalence and implementing BCG vaccination have negative statistical association with MIS-C cases and COVID-19 mortality.