COVID-19 and the BCG hypothesis: age group comparison between Italy, Spain, and Portugal. You can get a size sense of herd immunity and individual immunity effect.
The age group comparison between Italy, Spain, and Portugal should be interesting because three countries had different BCG policies and the same strain, BCG Denmark has been used. Let me look back at and dig into the detail of the BCG policy for each country.
- Italy: never mandatory
- Spain: mandatory from 1965 to 1981 for newborns from http://www.bcgatlas.org/. But the BCG Atlas is incomplete again. Schoolchildren from 6 to 14 years old had vaccinated from 1965 to 1976*. From 1956 to 1965, 80% of children who were 5 to 14 years old were vaccinated**.
-> Spanish from 39 to 78 years old has been vaccinated.
- Portugal: mandatory from 1965 to 2017 for newborns from http://www.bcgatlas.org/. And I guess same schoolchildren vaccination for Portuguese as Spainish***.
-> Portuguese from 3 to 78 old have been vaccinated.
*** Looking for a source.
Firstly, the below chart is deaths per 1M population by the age group. You can see Italy is the highest and Portugal is the lowest in all age groups.
The timing of the virus arrival may cause the difference but that alone cannot explain the difference between Spain and Portugal. The BCG vaccine may be working.
I am learning immunology through this COVID-19 pandemic for the first time and learned that there are two ways of how the immune system works: herd immunity and individual immunity. The BCG vaccine can work these two ways. You can easily see that Portugal has the lowest deaths per 1M population including the 80+ who were not BCG vaccinated. This is the herd immunity effect. The specialists are now arguing the herd immunity effect may be larger than the individual immunity from the BCG vaccination.
However, I did this age group comparison to identify the difference between those who have got vaccinated and those who have not; in other words, individual immunity.
Then, let me change the above chart to the below; relative deaths per 1M pop by age group, setting 80+ death per 1M population to 100 (80+=100) to compare the age group difference relatively, assuming most of 80+ have not been vaccinated in these three countries.
Hey, can you see a drop in ages younger than 79 in Spain and Portugal? To zoom in the younger ages, let me set not only 80+=100 in the three countries but also all age groups in Italy=100. Here is the third chart.
Wow, you can see an intriguing relative difference between those who were vaccinated and those who were not! Most of 39 to 78 years old were vaccinated in Spain and most of 3 to 78 years old were vaccinated in Portugal. This can be big evidence of individual immunity!
* Under 39 deaths in Italy 47, in Spain 37, and in Portugal 0 as of this analysis. I think this is statistically significant from my business analysis experience.
But remember that the herd immunity looks much larger by looking at 80+ in the first chart. Probably the specialist can quantify from this analysis.
This is the case with the weak strain, BCG Denmark. I guess that the strong strain, BCG Tokyo, would have a larger and longer effect. As Canada used the BCG Tokyo strain until 1960s-1970s, Canada vs the U.S. comparison will be another good set. I can already see that the relative deaths per 1M are small in the 50s to 70s in Canada. But, the U.S. doesn't disclose up-to-date age group data as of now. Let me work on it when the data is ready and I have time.
Sources of this analysis; accessed on 13 Apr.
(Added on 14 Apr)
The U.S. updated its age group data as of 13 Apr.
So let's compare it with Canadian age group data as of 13 Apr.
Firstly, let's check their BCG policies. Canadian BCG policy is quite complex. And the bad news is that Canada probably had used the BCG Connaught strain, a weak strain, though http://www.bcgatlas.org/ shows the BCG Tokyo strain.
- The U.S.: never mandatory
- Canada: The BCG policy in Canada is complex and may vary by provinces.
- From http://www.bcgatlas.org/, I would read that Canada had a "routine" BCG vaccination program until the 1960s-1970s and Canada uses BCG Tokyo 172 strain.
- https://www.tandfonline.com/doi/pdf/10.3402/ijch.v63i0.17908 says "The vaccine use in Canada dates to 1925, though its widespread use in publicly funded programs dates to 1948" and "BCG vaccine(Connaught, 1948)"
- https://www.sciencedirect.com/science/article/pii/S0264410X17308617 says "In the province of Québec, Canada, the Bacillus Calmette-Guérin (BCG) vaccine was offered to newborns and school-age children from the 1950s to mid-1970s"
- In the fall of 2011, the Sanofi BCG Connaught plant flooded caused supply shortage https://en.wikipedia.org/wiki/BCG_vaccine#Supply_shortage
- -> I assume Canada had its routine BCG program from 1948 to 1960s-1970s and Many Canadians from 40 to 79 years old have been vaccinated.
- -> I guess Canada had used the BCG Connaught strain until the Sanofi plant problem and started to use the BCG Tokyo strain after that.
The first chart is deaths per 1M population by the age group.
Canada does not have a statistically enough death number for under 39, only 4 deaths as of 13 Apr. If one or two deaths are added, the shape of the third chart changes a lot. I never hope so, but from the point of probability, death tolls under 39 in Canada will increase a bit.
(Added on 18 Apr)
I checked the latest Canadian report as of 16 Apr and found that death number for under 39 increased from 4 to 5 as I anticipated.
* Under 39 deaths in the U.S. is estimated to be 139 as of this analysis.
Comparing with the third chart of Italy and Spain, the BCG Connaught strain looks a bit more effective than the BCG Denmark strain. I don't have biochemical data that can compare the two strains but this is my guess from this analysis.
However, the BCG Connaught strain doesn't look effective as the BCG Tokyo strain. I had thought Canada uses the BCG Tokyo strain from http://www.bcgatlas.org/ and I was opportunistic about Canada, but it was not. I think Canadians should take precautions.
(Added on 6 May)
Let's do the same analysis for the U.K. and Ireland though it would be harder to visualize the gap as there is no non-BCG country among the two.
Firstly, let's check their BCG policies. Canadian BCG policy is quite complex. And the bad news is that Canada probably had used the BCG Connaught strain, a weak strain, though http://www.bcgatlas.org/ shows the BCG Tokyo strain.is a supplement analysis
- The U.K.:
- According to http://www.bcgatlas.org/
- Mandatory from 1953 to 2005 and the timing of vaccination was 12 or 13 yrs old
- The BCG strain is Evans Medical/Medeva that seems to be a weak strain
- ->27 to 80 years old have been vaccinated.
- According to http://www.bcgatlas.org/
- Mandatory from 1950s to now and the timing of vaccination is at birth
- The BCG strain is Danish SSI 1331 that is a weak strain
- According to https://www.irishtimes.com/news/played-major-role-in-the-fight-against-tb-1.1060781, it seems the BCG vaccination program started before the World War 2.
- ->0 to 80 years old have been vaccinated.
Ireland is simple. You can get the latest data from below. I picked up the latest one of 4 May as this analysis is to compare the relative death rate, not the absolute death rate. More data, the better.