Also many people fail to seroconvert after natural infection: https://wwwnc.cdc.gov/eid/article/27/9/21-1042-f2 https://wwwnc.cdc.gov/eid/article/27/9/21-1042-

Also many people fail to seroconvert after natural infection: https://wwwnc.cdc.gov/eid/article/27/9/21-1042-f2 https://wwwnc.cdc.gov/eid/article/27/9/21-1042-f2 And the virus contains immune evasion genes like ORF8 which evade humoral immunity responses by downregulating MHC-I: https://www.pnas.org/content/118/23/e2024202118 https://www.pnas.org/content/118/23/e2024202118 Nobody in their right mind would produce a vaccine with ORF8 in it since it defeats the whole purpose of stimulating T-cell and B-cell recognition. There's good reasons why natural immunity has been downplayed.