Conclusions
This is the first detailed case series showing COVID-19 recurrence with qRT-PCR positivity. For one individual, detection of phylogenetically distinct genomic sequences in the first and second episodes confirmed bona fide reinfection, but in most cases the data do not formally distinguish between reinfection and re-emergence of a chronic infection reservoir. These episodes were significantly associated with reduced Ab response during initial disease and argue the need for ongoing vigilance without an assumption of protection after a first episode.