Why is COVID-19 different where the expectation is that one vaccine will prove a panacea. The virus has already shown that it can mutate similar to the flu vaccine.
This should be compared more to something like the H1N1 outbreak, which was a single influenza virus that was particularly deadly for some subset of people. That was just one type of influenza.
if that makes any sense?
the yearly flu vaccines are tweaks to an already understood vaccine, (minor releases) Sometimes there are major releases but thats for a jab that targets a different class of flu (h5n1 vs h1n2)
this is an entirely new vaccine, for a virus that has never had a vaccine, so its more like a v1.0 release on a new platform.