Could BCG vaccine provide immunization against COVID-19? A potential relationship between Mycobacterium immunization and SARS-CoV-2

ABSTRACT

BACKGROUND: In March, we first hypothesized that;even though there was a higher number of COVID-19 patients in countries with a high population such as China, mortality rates in those countries were lower compared to other countries which do not have routine BCG vaccination. Therefore, we aimed to evaluate the accuracy of the hypothesis we made, by investigating the relationship of COVID-19 patients with BCG vaccine. METHODS: We retrospectively analyzed tuberculosis sequelae lesions and the presence of BCG vaccination in the radiological images and clinical reports of first fifty confirmed COVID-19 in-patients to evaluate our hypothesis in the shortest time. RESULTS: There was no pneumonia in 16 (32%) of patients. The mild, moderate and severe pneumonia ratios were 12 (24%), 10 (20%) and 12 (24%), respectively. Seven (1.4%) of the patients had respiratory failure and were followed up in the intensive care unit (ICU). Only one patient died during the follow-up time. CONCLUSIONS: We think that a considerably lower mortality rate, less severe course and more favorable prognosis of COVID-19 can be associated with the BCG vaccine. Current knowledge supports the utilization of a single-dose BCG vaccine to fight with this novel virus with its immunomodulatory properties, at least until the specific immunizations will be developed.