This study found no difference in rates of positive SARS-CoV-2 test results in adults who received BCG vaccination in childhood compared to those who did not. 

• The BCG vaccine was routinely administered to all newborns in Israel as part of the national immunization program between 1955 and 1982, with high uptake, then was not given to Israeli-born indivituals
• Had data on the 72,060 COVID-19 results performed in country from March 1 to April 5, 2020, all from approved laboratories. Groups divided into those born from 1979 to 1981 (aged 39-41 years- the BCG group) with those born from 1983 to 1985 (aged 35-37 years- the non-BCG group).
• Study included 3064 patients in the presumed BCG group and 2869 patients in the presumed non-BCG group
• There was no statistically significant difference in:
  • proportion of positive test results in the BCG-vaccinated group (361 [11.7%]) vs the unvaccinated group (299 [10.4%]; difference, 1.3%; 95% CI, −0.3% to 2.9%; P =0.09)
  • positivity rates per 100 000 (121 in vaccinated group vs 100 in unvaccinated group; difference, 21 per 100 000; 95% CI, −10 to 50 per 100 000; P = 0.15)
• 1 case of severe disease (mechanical ventilation or intensive care unit admission) in each group
• No deaths were reported

Summary: While there are multiple limitations to this study, it does not support the idea that BCG vaccination in childhood has a protective effect against COVID-19 in adulthood.