The New SARS-CoV-2 Variants and Their Epidemiological Impact in Mexico

Abstract

The COVID-19 disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus started its deadly journey into a global pandemic in Wuhan, China, in December 2019, where it was first isolated. Subsequently, multiple variants of the virus have been identified worldwide. In this review, we discuss the overall landscape of the pandemic in Mexico, including its most prevalent variants, their surveillance at a genomic level, and how they impacted the epidemiology of the disease. We also evaluate the heterologous vaccination in Mexico and how it may have influenced group immunity and helped mitigate the pandemic. Finally, we present an integrated view that could help us to understand the pandemic and serve as an example of the situation in Latin America.

Keywords: COVID-19 pandemic; SARS-CoV-2 variants; genomic vigilance; vaccination.

FIG 1

Epidemiological and genomic surveillance in Mexico. (A) Daily average of new confirmed cases and deaths in Mexico in the context of four pandemic waves. The left y axis portrays the number of newly confirmed patients diagnosed daily, and the right y axis is the total number of deaths on each date. Both metrics were calculated as rolling 7-day averages using the date when each patient was registered. The first day of each month is marked on the X-axis. (B) Percentage of deceased and surviving patients throughout the pandemic as shown by age categories (5-year step). The type of patient is shown separately. (C) Average sequenced genomes per rolling 14-day period based on the day of collection of each sample. The top 6 most abundant lineages are shown in the legend. Confirmed cases are shown in a dashed line for context only.

FIG 2

Vaccination in Mexico. (A) Mechanisms of the adaptive immunity after vaccination for controlling SARS-CoV-2 infection. (B) Total doses and percentage of each vaccine that has been acquired in Mexico. These are clustered by type of vaccine, along with example particles shown on the right. (C) Daily percentage of confirmed cases in each age group based on vaccination program (based on 7-day rolling averages). The first day of each vaccination stage (per age group) is marked with a diamond. The span of each of the fourth waves is shown as bars at the bottom. (D) Daily lethality per age group (based on 7-day rolling averages). Confirmed cases and deaths were sorted by the same date of the registry. The first day of each vaccination stage (per age group) is marked with a diamond.