So there's some evidence now that you can get COVID-19 more than once-- that stuff isn't well known yet, so I'm not speculating on that in regards to COVID, in particular.

A friend raised a valid Q, though: can you make an effective vaccine against diseases you can get >1x?

Like I know we need annual flu shots, but my perception of that is it's bc the flu virus changes.

Are there examples of other diseases that you would normally be able to catch more than once, but we have an effective vaccine for?

The idea my friend raised was "if antibodies to the pathogen don't confer immunity, wouldn't a vaccine not work either?"

I know an ok amount about vaccines, but not sure the answer to that one-- can immunity conferred by vaccines be longer-lasting than body's immune response?