Evidence of SARS-CoV-2 reinfection within the same clade in Ecuador: A case study.

Objectives: To date, reported SARS-CoV-2 reinfection cases are mainly from strains belonging to different clades. As the pandemic advances, a few lineages have become dominant in certain areas leading to reinfections by similar strains. Here, we report a reinfection case within the same clade of the initial infection in a symptomatic 28-year-old-male in Quito-Ecuador.

Methods: Infection was detected by reverse transcription-polymerase chain reaction, and immune response evaluated by antibody testing. Whole-genome sequencing was performed and phylogenetic analysis conducted to determine relatedness.

Results: Both the infection and the reinfection strains were assigned as Nextstrain 20B, Pangolin lineage B.1.1 and GISAID clade O. Our analysis indicated 4-6 fold more nucleotide changes than are expected for reactivation or persistence compared with the natural rate of SARS-CoV-2 mutation (∼2-3 nucleotide changes per month), thus supporting reinfection. Furthermore, approximately 3 months after the second infection, COVID-19 antibodies were not detectable in the patient, suggesting potential vulnerability to a third infection.

Conclusions: Our results showed evidence of SARS-CoV-2 reinfection within the same clade in Ecuador, indicating that previous exposure to SARS-CoV-2 does not guarantee immunity in all cases.