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This is a false, irresponsible statement by the WHO, which will panic people in the name of not raising false hope. I will reply to this thread with evidence that infection confers at least temporary immunity https://twitter.com/MackayIM/status/1254004568758693889
Experimentally infected macaques were protected against challenge: https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1
All those reports of "reinfection" you've heard were either resurgent infections or bad tests: https://twitter.com/RELenski/status/1253421497172946954
Recovered individuals have neutralizing antibodies: https://www.medrxiv.org/content/10.1101/2020.03.30.20047365v2
Convalescent plasma therapy seems to work, which suggests that neutralizing antibodies made by recovered individuals are effective in vivo: https://www.pnas.org/content/early/2020/04/02/2004168117.short
In short: are we *100% sure* yet that an epidemiologically meaningful percentage of recovered people develop protective immunity? No, of course not. Is there evidence? Yes, there's evidence. (end)
Addendum: and no, this immunity may not last forever, but for a variety of reasons it is likely to last long enough to matter epidemiologically
Just gonna throw this essay on the end here, as it seems relevant http://dylanhmorris.com/post/false-certainty/
Another addendum: some people feel I should be criticizing the Reuters headline rather than the WHO statement. The statement is intended as a warning against "immunity passports"—a measure I'm also very leery of. But the exact line is still false and misleading...
"There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection". Really can't say "no" when you mean "insufficient", or you'll get headlines like the Reuters one. Can't blame journos https://www.who.int/news-room/commentaries/detail/immunity-passports-in-the-context-of-covid-19
Seriously, you can't just blame the journalists
https://twitter.com/WHO/status/1253995619921821698
https://twitter.com/WHO/status/1253995619921821698
Update: the @WHO has issued a very helpful clarification. Grateful that they are taking this seriously. https://twitter.com/WHO/status/1254160937805926405
