Exercising caution in correlating COVID-19 incidence and mortality rates with BCG vaccination policies due to variable rates of SARS CoV-2 testing

Janine Hensel; Daniel J McGrail; Kathleen M McAndrews; Dara Dowlatshahi; Valerie S LeBleu; Raghu Kalluri

Although not studied here, host haplotypes may also inform on the incidence COVID-19 cases. Finally, time since first exposure rates, as well as population adherence to social distancing measures, may also influence the evolving COVID-19 data collection. To date, social distancing remains critical in slowing down the number of new cases over time. Data from the Australian clinical testing currently underway to assess whether the BCG vaccination may be protective against COVID-19 (clinicaltrials.gov, NCT04327206) will likely shed more light on the possible use of BCG in decreasing CoV-2 infection and associated mortality. Figure 3 . Distribution of COVID-19 cases and mortality and BCG vaccination policy implementation (A) TB incidence in per 100,000 inhabitants shown as mean ± SEM for all three groups of BCG policies (never (red), past (green) and current (blue) BCG vaccination policy). One-way ANOVA with Kruskal-Wallis performed. (B) Total COVID-19 cases per 1M inhabitants (left panel) and percent mortality per total COVID-19 cases (right panel) is shown as mean ± SEM for all countries that had a universal BCG policy in the past and discontinued that policy £ 20 years ago or ³ 20 years ago. Mann-Whitney test performed. (C) Correlation graph of total numbers of COVID-19 cases per 1M inhabitants (left panel) percent mortality per total COVID-19 cases (right panel) and the year the universal BCG policy was introduced. (D,E,F) Correlation graph showing percent mortality per total COVID-19 cases and the time since first confirmed COVID-19 case in days in countries that never had a universal BCG policy (D), had a universal BCG policy in the past (E), or have a current universal BCG policy (F). Not significant (ns), p ³0.05. *** p < 0.001, **** p <0.0001.