ISLAMABAD, JUNE 02 (ABC): Countries that had compulsory bacillus Calmette-Guérin (BCG) vaccination at least until 2000 appear to have built up a degree of “herd immunity” against COVID-19, a new study suggests.
There would have been approximately 80% fewer COVID-19 deaths in the United States by March 29, 2020, if the country had employed mandatory BCG vaccination since at least 2000, according to the new research.
The number of these deaths in the U.S. by March 29 was 2,467, but it would have been 468 with mandatory vaccination, say the scientists.
BCG vaccination is usually given at birth or during childhood to protect against tuberculosis (TB). But there is also evidence that it protects against other respiratory infections and lung cancer. In addition, it is an effective treatment for some forms of bladder cancer.
A study in 2018 found that the vaccine appeared to “reprogram” immune cells to produce more of a particular immune signaling molecule. This, in turn, boosted immunity against a viral infection.
Previous studies have found a link between BCG vaccination and a slower spread of COVID-19 in populations around the world, but they failed to account for national differences in test availability and data reporting.
The new model attempts to get around this limitation by using the initial rate of increase in the number of reported cases and deaths, rather than the absolute numbers.
For each country, the researchers focused on a 30-day period after the first 100 confirmed cases or the first death.
Provided any national differences in reporting remained stable during this period, say the scientists, this should eliminate the effect of this bias on the data.
