SARS-CoV-2 Omicron variants BA.4 and BA.5 dominated the fifth COVID-19 epidemiological wave in Mexico

Abstract

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' abundance, 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 the most abundant, BA.2.9, BA.2.12.1, BA.5.1, BA.5.2, BA.5.2.1 and BA.4.1, circulated 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 significant entry point and contributed to introducing and evolving novel variants in Mexico. Furthermore, a differential distribution was observed for certain subvariants among specific States through time, which may have contributed to the overall increased diversity observed during this wave compared to the previous ones. This study highlights the importance of sustaining genomic surveillance to identify novel variants that may impact public health.

Mortality-Associated Sars-Cov-2 Genomic Variants From Patients Hospitalized for Severe Pneumonia in Aguascalientes, Mexico From 2020 to 2023

“…This study also confirms previous findings that BA.5 Omicron variant dominated the fifth epidemic wave (summer 2022) in Mexico, replacing BA.1 and BA.2 and that Aguascalientes was among the states with a transitory presence of BA.2 and a low presence of BA.4 [Taboada et al 2023, Castelán-Sánchez et al 2023, [García-López et al, 2023].…”

“…Mexico established a comprehensive epidemiological follow-up of the SARS-CoV-2 pandemic, carried out by various entities such as public health organizations, academic institutions, and private entities. The collaborative efforts of these entities underscore the significance of a multi-sectoral approach to tackling pandemics of this nature [Hernández-Huerta et al 2021, Taboada et al 2021, Taboada et al 2023]. The World Health Organization (WHO) has confirmed the presence of all Variants of Concern (VOCs) in Mexico as of the latest reporting period.…”