[AnnieK]

Originally Posted by Toy Soldier

No side effect usually means no immune response, which usually means immunity is already present... So the years when he has no side effects its likely that his vaccine from the previous year is still giving protection.

Interestingly, on the natural immunity front, one of my wife's friends who got the vaccine had no side effects at all - but she tested positive for antibodies when her whole workplace was tested back in September. She had never had symptoms so she must have had asymptomatic Covid at some point. But having no immune response to the vaccine is interesting as it does mean she most likely still has antibodies from that exposure.

She works in a care home and something like 30% of the staff tested positive for antibodies when only a couple of them had ever had any symptoms .

Ah, that's interesting and makes sense TS. I didn't know that so thanks for the info