that population age is a very significant confounding factor
that BCG vaccination may have little or no causal link to infection rates
This study shows that population age is a very significant confounding factor that explains the rates of infections much better and has a solid biology mechanism which explains this correlation .
It suggests that BCG vaccination may have little or no causal link to infection rates and advises that any follow up studies should control for several confounding factors , such as population age , ethnicity , rates of certain chronic diseases , time from community spread start date , major public policy decisions and income levels .