Paper and Threads

Within the last weeks Covid-19 reinfections were reported in 4 patients, separated in time from their first episode.  Sometimes patients continue to have a positive molecular virus test after their Covid-19 infection, but the PCR test is able to measure remaining dead virus after recovery. RNA viruses mutate slowly, usually in unimportant portions of the virus.  The ability to sequence the RNA allows scientists to detect mutations - and that is how they determined that NYC was infected with a European strain of SARS-CoV-2, not the Wuhan strain.  The European strain was infecting communities in NYC long before there was any control of the planes arriving from Europe or even China. 

I was surprised that in the 4 patients with recurrent disease (one each from China, Belgium, Netherlands, and Nevada), scientists were able to compare the SARS-CoV-2 virus that was isolated from both their first and second positive SARS-CoV-2 virus samples.  There were different mutations present when the rwo samples were compared, thus demonstrating that these were 2 separate infections in each patient.  It is not clear how many cases of reinfection will be reported, virus samples from each episode must be available for testing.  These cases were each reported online, not in published scientific papers that I could find.