Simple but strong evidence of the BCG Tokyo strain efficacy against COVID-19

I have heard so many arguments that there are many more factors that affect the country/region difference such as virus mutations, arrival timing, genes, masks, hygiene, voice language, food spices, etc. I totally agree that there could be many more factors. 

Here is simple but strong evidence of the BCG Tokyo strain efficacy against COVID-19.

One Japanese died of COVID-19 in the U.S at the end of April. It is the first COVID-19 Japanese death in the U.S. Let me calculate and summarize the deaths per 1 million population.

Deaths per 1M at the end of April.

• The U.S.: around 200
• Asian American: 110
• Japanese in the U.S.: around 2
• Japan: 3

1) The death rate in Japan/ese is one-hundredths of the U.S., less than half of the flu.

2) There should be other biological reasons other than genes. My hypothesis is that BCG vaccination is the key reason.

The BCG Tokyo strain may work as ready-to-use vaccination against COVID-19. 
If an adult has BCC vaccinated before, the Mantoux test can work as a second-best solution to resensitize his/her immune memory. This is good because we can keep the necessary BCG vaccine for infants if seniors can use the Mantoux test. 

I wonder why only a few researchers work on this hypothesis. I have heard that pharmaceutical companies are not interested in the BCG vaccine because it is a very low margin product. I believe all the governments look into this hypothesis.

Source
https://www.worldometers.info/coronavirus/
https://www.apmresearchlab.org/covid/deaths-by-race
https://www.mofa.go.jp/mofaj/toko/page22_000043.html