In yesterday's update #15 on corona with Prof Christian Drosten [1] he is asked about this study and voices scepticism regarding its reliability. They publish

In yesterday's update #15 on corona with Prof Christian Drosten [1] he is asked about this study and voices scepticism regarding its reliability. They publish a transcript for every episode. For this one it isn't available yet. Otherwise I'd c/p the section. 1: https://www.ndr.de/nachrichten/info/15-Infizierte-werden-offenbar-immun,audio654608.html https://www.ndr.de/nachrichten/info/15-Infizierte-werden-off...