@angelovalidiya @bartbuk Thank you for your guidance.
In a 2003 study, BCG vaccination in the elderly was effective in preventing pneumonia.
This paper doesn't seem to be well known because it's in Japanese.
@_LeMoog_ @gerdosi I am a reader of this BCG hypothesis website.
I have seen the following paper here.
"Establishment of BCG Vaccine Therapy for the Prevention of Elderly Pneumonia"