This is what the "immune system" does. No vaccine necessary...

Reinfections cleared faster than initial COVID-19 infections, including among people who never received a COVID-19 vaccine, according to a new study.⁠
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People infected with COVID-19 for a second time cleared the illness a mean of 6.6 days, compared with a mean of 9.3 days for the initial infection, U.S. and British researchers reported in the paper.⁠
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Researchers drew the findings from 1,796 first infections and 193 second infections.⁠
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The difference held for a subset of 71 people who had two well-documented infections.