maybe Bacillus Calmette-Guérin (BCG) this is the old, multifaceted and controversial vaccine is a bet to stimulate immunity could help reduction in the prevalence and severity of coronavirus disease coronavirus (COVID-19).

Yes there is definite relationship between BCG vaccine and covid 19 as based on the article published in biomedical science some of the inferences are drawn as the developed countries which stopped BCG Vaccinations in their EPI programme are facing a high mortality rate than the people of developing world.

Also it is now a known fact that one of the oldest vaccine for preventing Tuberculosis i.e the BCG is able to treat some of other critical disorders and infections for example Leprosy, Burili Ulcer, Bladder Cancer.

Dr.Fautzman in MIT USA is already carrying out clinical trial on probable usage of BCG Vaccine to revert Diabetes type-I.

With Respect to Covid-19 many groups from Australia, Germany, Netherlands and France and India are conducting clinical trials to find out if there is any relationship between BCG vaccine and covid 19 .

Ofcourse new recombinant BCG candidate vaccines shall also be studied.

There are, indeed, several studies registered at ClinicalTrials.gov on the role of BCG vaccination in COVID-19, butt nothing has been published so far. So we currently do not know whether BCG will protect against SARS-CoV-2 infection.

Moderna's Coronavirus vaccine shows promising early results in human experiments

https://www.nytimes.com/2020/05/18/health/coronavirus-vaccine-moderna.html

Please read this article.

Also please check the following articles.

Have a look at the following articles about role of BCG in COVID-19:

Preprint Differential COVID-19-attributable mortality and BCG vaccine...

https://www.medrxiv.org/content/10.1101/2020.03.24.20042937v1

Article BCG vaccination at three different age groups: Response and ...

Preprint BCG VACCINES MAY NOT REDUCE COVID-19 MORTALITY RATES

Preprint Correlation between universal BCG vaccination policy and red...

Considering long-term boosting of innate immune responses, termed ‘trained immunity’, a number of clinical studies are underway on the protective effect of Bacille Calmette-Guérin (BCG) vaccine in COVID-19.

Please have a look at the link below:

Article Demystifying BCG Vaccine and COVID-19 Relationship

Please have a look at our article link below:

Article Convergence between global BCG vaccination and COVID‐19 pandemic

Have a look at this useful link.

https://www.nature.com/articles/s41598-021-87731-9.pdf