Comment by pazimzadeh
2 years ago
> We found clean, CAUSAL evidence that the shingles vaccine prevents a good chunk of dementia cases. So, could a virus cause Alzheimer’s > YES
Not to be pedantic, but the BCG vaccine is used as treatment for bladder cancer but nobody is claiming that Tuberculosis causes bladder cancer. In order to claim that shingles is causal (rather than that the vaccine affects immune/other function), you would have to fulfill Koch's postulates or measure virus levels in various patients.
The effect is still interesting.
I think they said that. “CAUSAL evidence that the shingles vaccine prevents”, yes; “could a virus cause Alzheimer’s”, yes. The causal claim is for the vaccine, not the virus.
"Could be" is the way we describe possibility in English. There may be an enormous amount of evidence that tuberculosis doesn't directly or indirectly cause bladder cancer. None of that evidence comes from the fact that vaccination against TB is effective against bladder cancer. That fact in isolation could obviously be used as supporting evidence for TB being the cause of bladder cancer.