Rationale: The first descriptions of reinfection by SARS-CoV-2 have been recently reported. However, these studies focus exclusively on the reinfected case, without considering the epidemiological context of the event.
Objectives: To perform a complete analysis of the sequential infections and transmission events around a SARS-CoV-2 reinfection, including the infection events preceding it, the exposure and subsequent transmissions.
Methods: Our analysis was supported by host genetics, viral whole genome sequencing, phylogenomic viral population analysis, and refined epidemiological data obtained from interviews with the involved subjects.
Results: The reinfection involved a 53-year-old woman with asthma (Case A), with a first COVID-19 episode in April-2020 and a much more severe second episode four months and a half later, with COVID-19 seroconversion in August, and requiring hospital admission. An extended genomic analysis allowed us to demonstrate that the strain involved in Case A´s reinfection was circulating in the epidemiological context of Case A and was also transmitted subsequently from Case A to her family context. The reinfection was also supported by a phylogenetic analysis, including 348 strains from Madrid, which revealed that the strain involved in the reinfection was circulating by the time Case A suffered the second episode, August/September-2020, but absent at the time range corresponding to Case A´s first episode.
Conclusion: We present the first complete analysis of the epidemiological scenario around a reinfection by SARS-CoV-2, more severe than the first episode, including three cases preceding the reinfection, the reinfected case per se, and the subsequent transmission to another seven cases.