The evolutionary landscape of SARS-CoV-2 variant B.1.1.519 and its clinical impact in Mexico City

The SARS-CoV-2 pandemic is one of the most concerning health problems around the globe. We report the emergence of SARS-CoV-2 variant B.1.1.519 in Mexico City. This variant represented up to 90% of sequenced cases in February 2021. It is characterized by three amino acid changes in the spike protein: T478K, P681H, and T732A. We report the effective reproduction number of B.1.1.519 and present evidence of its geographical origin based on phylogenetic analysis. We also studied its evolution via haplotype analysis and identified the most recurrent haplotypes. Finally, we studied the clinical impact of B.1.1.519: patients infected with variant B.1.1.519 showed a highly significant adjusted odds ratio (aOR) increase of 1.85 over non-B.1.1.519 patients for developing a severe/critical outcome (P = 0.000296, 1.33–2.6 95% CI) and a 2.35-fold increase for hospitalization (P = 0.005, 1.32–4.34 95% CI). The continuous monitoring of this and other variants will be required to control the ongoing pandemic as it evolves.