Covid. Reinfection. UK study. Not happening. 40 out of 6500 cases found. And even those are "probable" and "possible" cases whatever those might mean in medical terms. Not "confirmed" "widespread" "proven" or anything which should have been expected by now.
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https://www.aljazeera.com/news/2021/1/14/covid-infection-gives-some-immunity-for-5-months-uk-study