@TheMadPirate
Mostly because the virus went through a few mutations since then.
@alyx Doesn’t people become more resistant to variants of a virus in time when they develop natural immunity ?. You know, like influenza’s seasonal variants.
@TheMadPirate
Not necessarily, depends a lot on the mutations themselves. The real problem though is only a small percentage of the population had the actual disease, and developed natural immunity. And even for those, we already know that antibody number go down in time. In any case, relying on people developing natural immunity could translate to the pandemic lasting decades.
@TheMadPirate
Covid and the flu are very different viruses, despise what the "it's just like the flu" crowd wants you to believe. There's no guarantee that what works for the flu would work for covid.