In Mexico, the BA.4 and BA.5 Omicron variants dominated the fifth epidemic wave (summer 2022), superseding BA.2, which had circulated during the inter-wave period. The present study uses genome sequencing and statistical and phylogenetic analyses to examine these variants’ prevalence, distribution, and genetic diversity in Mexico from April to August 2022. Over 35% of the sequenced genomes in this period corresponded to the BA.2 variant, 8% to the BA.4, and 56% to the BA.5 variant. Multiple subvariants were identified, but only BA.2.9, BA.2.12.1, BA.5.1, BA.5.2, BA.5.2.1, and BA.4.1 circulated throughout the fifth wave across the entire country, not forming geographical clusters. Contrastingly, other subvariants exhibited a geographically restricted distribution, most notably in the Southeast region, which showed a distinct subvariant dynamic. This study supports previous results showing that this region may be a major entry point and may have contributed to the introduction and evolution of novel variants in Mexico. Furthermore, a differential distribution was observed for certain subvariants among specific States throughout time, which may have contributed to the overall increased diversity observed during this wave compared to the previous one. This study highlights the importance of sustaining genomic surveillance to identify novel variants that may impact public health.

Background SARS-CoV-2 is a novel coronavirus described for the first time in China in December 2019. This virus can cause a disease that ranges in spectrum from asymptomatic to severe respiratory disease with multiorgan failure, and the most severe cases are associated with some comorbidities and patient age. However, there are patients who do not have those risk factors who still develop serious disease. Methods In this study, we identified the presence of other respiratory viruses in positive cases of COVID-19 in Mexico to determine if any coinfections were correlated with more severe manifestations of COVID-19. We analysed 103 confirmed cases of COVID-19 using RT-qPCR for the detection of 16 other respiratory viruses. Results Of the cases analysed, 14 (13.6%) were cases of coinfection, and 92% of them never required hospitalization, even when comorbidities and advanced age were involved. There weren’t significant differences between the presence of comorbidities and the mean ages of the groups Conclusions These results suggest that coinfection is not related to more severe COVID-19 and that, depending on the virus involved, it could even lead to a better prognosis. We believe that our findings may lay the groundwork for new studies aimed at determining the biological mechanism by which this phenomenon occurs and for proposing corresponding strategies to limit the progression to severe cases of COVID-19.