Dr. Yeadon has said that those who contracted SARS1 in 2003 have been tested this year with SARS1 and are still immune.
Then those people were tested with SARS2 (Covid) and were immune to that as well. The two viruses have 22% different genomes but are otherwise the same.
“Variants” average about 1% difference from Covid, so there’s no need to fear them or be vaccinated for them.
The Covid test does not identify the virus or the illness, so if someone was ill with other coronaviruses (influenza etc.) they would also have protection.
There are other corona
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