Factors determining COVID-19 pneumonia severity in a country with routine BCG vaccination

Background The impact of countries' bacillus Calmette-Guerin (BCG) vaccination policies on the course of coronavirus disease (COVID-19) outbreak is a curiosity. In this study, the relationship between BCG vaccination status and severity of COVID-19 pneumonia and the factors affecting disease severity were investigated. Methods A retrospective cross-sectional study was conducted between March and June 2020 in patients diagnosed with COVID-19 pneumonia, confirmed by severe acute respiratory syndrome coronavirus-2 polymerase chain reaction positivity in a nasopharyngeal sample and pulmonary infiltrates in computed chest tomography, in a state hospital in Istanbul, Turkey. Socio-demographic features, body mass index, smoking status, concomitant diseases, income rates and BCG vaccination status of subjects were analyzed. Result The study population comprised 123 adults with COVID-19 pneumonia [mean age = 49 center dot 7 years, standard deviation = 13 center dot 3 years; 82 (66 center dot 7%) male]. While the rate of cases vaccinated with BCG is lower (68 center dot 5versus88 center dot 2%,P = 0 center dot 026), mean age (54 center dot 0 +/- 11 center dot 5 yearsversus38 center dot 3 +/- 10 center dot 7 years;P < 0 center dot 001), diabetes (32 center dot 6versus5 center dot 9%,P = 0 center dot 002) and low income (84 center dot 3versus52 center dot 9%,P < 0 center dot 001) are higher in patients with severe disease compared to those with mild disease. According to multivariate analysis increasing age [odds ratio (OR) = 1 center dot 119; 95% confidence interval (CI) = 1 center dot 062-1 center dot 178,P < 0 center dot 001] and low income (OR = 3 center dot 209; 95% CI = 1 center dot 008-10 center dot 222,P = 0 center dot 049) are associated with severe disease in COVID-19 pneumonia. Conclusion This study reveals that BCG vaccination is not associated with disease severity in COVID-19 pneumonia. Age and low income are the main determinants of severe COVID-19 pneumonia.