One study suggests that the effective memory of Covid-19 in people who have had the virus is 93 percent at 6 months, and 92 percent at one year/ This study offers more evidence that catching the virus is an effective immunization and therapeutic potency that matches or exceeding vaccination levels perhaps for longer periods of times without additional risk to the person or to anyone else around them.
From doctorsandscientistsdeclaration.org – COVID-Recovered Immunity is Durable
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One-year sustained cellular and humoral immunities of COVID-19 convalescents, Jie Zhang, Hao Lin, Beiwei Ye, Min Zhao, Jianbo Zhan, et al.
SARS-CoV-2-specific IgG antibodies, and also NAb can persist among over 95% COVID-19 convalescents from 6 months to 12 months after disease onset. At least 19/71 (26%) of COVID-19 convalescents (double positive in ELISA and MCLIA) had detectable circulating IgM antibody against SARS-CoV-2 at 12m post-disease onset. Notably, the percentages of convalescents with positive SARS-CoV-2-specific T-cell responses (at least one of the SARS-CoV-2 antigen S1, S2, M and N protein) were 71/76 (93%) and 67/73 (92%) at 6m and 12m, respectively. Furthermore, both antibody and T-cell memory levels of the convalescents were positively associated with their disease severity.