Background: Reinfections with SARS-CoV-2 have been reported and most cases were classified as mild. Reports of persistent infection with SARS-CoV-2 are rare.
Aim: To investigate the frequency of recurrent and persistent infection with SARS-CoV-2.
Methods: Possible cases of reinfection and persistent infection were retrospectively identified in a database of 59,998 patients. Deep sequencing of SARS-CoV-2 genomes was performed.
Results: We report the first case of COVID-19 reinfection in Sweden and three cases of infection with persistence over several months. The rate of sequencing-verified reinfection was 0.02% (one patient out of 6014 patients testing positive during the period).
Conclusions: The reinfected patient had mild symptoms during the second episode, which might reflect partial immunity. The frequency of reinfection during the first wave of the pandemic in western Sweden was very low. Our results indicate that elderly with a putative reinfection more likely have persistent COVID-19.
Keywords: SARS-CoV-2; persistent infection; reinfection.