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

Sevillano, Gabriela; Ortega-Paredes, David; Loaiza, Karen; Zurita-Salinas, Camilo; Zurita, Jeannete

OBJECTIVES: To date, reported SARS-CoV-2 reinfection cases are mainly based on strains belonging to different clades. As the pandemic advances, a few lineages have become dominant in certain areas which has led to a new type of reinfection by extremely similar strains. Here, we report a reinfection within the same clade in a symptomatic 28-year-old-male in Quito-Ecuador. METHODS: Infection was detected by RT-PCR, immune response was evaluated by antibody testing, patient identity was confirmed by fingerprint. Relatedness was determined through bioinformatics analysis of Illumina WGS samples. 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 more nucleotide changes than what is expected for reactivation or persistence, 4-6 fold more, based on the natural rate of mutation of SARS-CoV-2 of (≈2-3 nucleotide changes per month), thus supporting a reinfection. Furthermore, after three months of the second infection the patient appears to be susceptible to a new SARS-CoV-2 infection. CONCLUSIONS: Our results showed evidence of SARS-CoV-2 reinfection within the same clade in Ecuador proving that previous exposure to SARS-CoV-2 does not guarantee immunity in all cases.