Evidence of SARS-CoV-2 symptomatic reinfection in four healthcare professionals from the same hospital despite the presence of antibodies.

OBJECTIVES: Since the onset of the COVID-19 pandemic, cases of reinfection with SARS-CoV-2 have been reported, raising additional public health concerns. SARS-CoV-2 reinfection was assessed in healthcare workers (HCWs) in Tunisia because they are at the greatest exposure to infection by different variants. METHODS: We conducted whole-genome sequencing of the viral RNA from clinical specimens collected during the initial infection and the suspected reinfection from 4 HCWs, who were working at the Habib Bourguiba University Hospital (Sfax, Tunisia) and retested positive for SARS-CoV-2 through reverse transcriptase-polymerase chain reaction (RT-PCR) after recovery from a first infection. A total of 8 viral RNAs from the patients' respiratory specimens were obtained, which allowed us to characterize the differences between viral genomes from initial infection and positive retest. The serology status for total Ig, IgG, and IgM against SARS-CoV-2 was also determined and followed after the first infection. RESULTS: We confirmed through whole-genome sequencing of the viral samples that all 4 cases experienced a reinfection event. The interval between the 2 infection events ranged between 45 and 141 days, and symptoms were milder in the second infection for 2 patients and more severe for the remaining 2 patients. Reinfection occurred in all 4 patients despite the presence of antibodies in 3 of them. CONCLUSION: This study adds to the rapidly growing evidence of COVID-19 reinfection, where viral sequences were used to confirm infection by distinct isolates of SARS-CoV-2 in HCWs. These findings suggest that individuals who are exposed to different SARS-CoV-2 variants might not acquire sufficiently protective immunity through natural infection and emphasize the necessity of their vaccination and the regular follow-up of their immune status both in quantitative and qualitative terms.

SARS-CoV-2 tracking in Tunisia through next-generation sequencing: lessons for the future.

In this study, data available from GISAID on the whole-genome sequences of SARS-CoV-2 variants circulating in Tunisia were analyzed, and the prevalences of those variants in Tunisia were compared to their prevalences in other North African countries and around the world. Our results show new mutations and different prevalences of some lineages. In particular, new sets of mutations were identified in the spike protein of the virus during the analysis of 85 Tunisian samples, and the lineage B1.160 was found to be the most prevalent (18%) lineage in Tunisia. The prevalence of this lineage in Tunisia was significantly higher than its prevalence worldwide and in samples from neighboring countries (3%). This preliminary study shows the importance of tracking virus variants by next-generation sequencing in order to assess the dynamics of the COVID-19 pandemic and the impact of vaccination on the evolution of the virus.