A new scientific study has discovered a possible correlation between countries where it is mandatory to be vaccinated against tuberculosis, also called “Bacillus Calmette-Guerin” (BCG), and the impact of the new coronavirus.

"We found that countries without universal policies of BCG vaccination (Italy, Netherlands, USA) have been more severely affected compared to countries with universal and long-standing BCG policies", the study's authors wrote.
https://www.euronews.com/2020/04/06/has-the-key-to-a-coronoavirus-vaccine-been-staring-us-in-the-face-for-a-century