Maybe for the synthetic immunity (who knows).
But in any case, SARS-1 and covid are about 80% similar. The "variants" of different covids are about 99.7% similar. Draw your own conclusions.
So far the mRNA vaccines have shown strong effectiveness against the variants, but the others like AZ and the Chinese/Russian vaccines much less so. It's also worth noting that natural immunity is a somewhat random process (more random than the antibodies produced with vaccines) and not everyone develops the same level of protection.
> Next, we showed that patients (n = 23) who recovered from SARS (the disease associated with SARS-CoV infection) possess long-lasting memory T cells that are reactive to the N protein of SARS-CoV 17 years after the outbreak of SARS in 2003; these T cells displayed robust cross-reactivity to the N protein of SARS-CoV-2.
BTW people and chimpanzees share 99% of their DNA. We're basically the same, aren't we. /s
80% is not close at all, and 99.7% still can render a vaccine ineffective, of course the specifics matter.