The molecular epidemiology of SARS-CoV-2 in the Pityusic Islands shows multiple introductions and fast replacements of variants in a touristic worldwide hot spot

Abstract

The public health emergency caused by the Covid-19 outbreak in March 2020 encouraged worldwide initiatives to monitor the genetic diversity and features of the SARS-CoV-2 circulating variants, mainly based on the genomic surveillance. However, due to the impossibility to carry out extensive sequencing in resource-limited hospitals, other PCR-based strategies could be applied to efficiently monitor the circulating variants without the need to greatly expand the sequencing capacity. In our case, overpassing the technical limitations inherent to a second level hospital, we were able to characterize the weekly distribution of SARS-CoV-2 by the RT-qPCR amplification patterns visualization, single nucleotide polymorphism genotyping, and sequencing of randomly selected samples. All these molecular approaches allowed us to trace the epidemiology of SARS-CoV-2 viruses circulating in Ibiza and Formentera (Balearic Islands, Spain) during the third to the sixth pandemic waves (January 2021-July 2022), in which three major lineages that were considered as VOCs (Alpha, Delta, and Omicron), and many other non-VOC variants were detected and tracked.