Recurrent Dissemination of SARS-CoV-2 Through the Uruguayan-Brazilian Border.

Daiana Mir,Marilda Tereza Mar Da Rosa,Natalia Reyes,Verónica Noya,Tania Possi,Cecilia Mathó,Cecilia Alonso,Matías Salvo,Matías Castells,Mariana Brandes,María José Benítez-Galeano,Tamara Fernández-Calero,Ignacio Ferrés,Ighor Arantes,Lucía Spangenberg,Yasser Vega,Tatiana Schäffer Gregianini,Natalia Rego,Leticia Maya,Rodney Colina,Martín Graña,Pablo Smircich,Matías Victoria,Camila Simoes,Gonzalo Bello,Letícia Garay Martins,Cecilia Salazar,Luciana Appolinario,Paola Cristina Resende,Marilda Mendonça Siqueira,Rafael Sebastián Fort,Ana Carolina Da Fonseca Mendonça ,Fernando Do Couto Motta ,Mailén Arleo ,Andrés Lizasoain ,José Sotelo Silveira ,Fernando López Tort

doi:10.3389/fmicb.2021.653986

Abstract

Uruguay is one of the few countries in the Americas that successfully contained the coronavirus disease 19 (COVID-19) epidemic during the first half of 2020. Nevertheless, the intensive human mobility across the dry border with Brazil is a major challenge for public health authorities. We aimed to investigate the origin of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains detected in Uruguayan localities bordering Brazil as well as to measure the viral flux across this ∼1,100 km uninterrupted dry frontier. Using complete SARS-CoV-2 genomes from the Uruguayan–Brazilian bordering region and phylogeographic analyses, we inferred the virus dissemination frequency between Brazil and Uruguay and characterized local outbreak dynamics during the first months (May–July) of the pandemic. Phylogenetic analyses revealed multiple introductions of SARS-CoV-2 Brazilian lineages B.1.1.28 and B.1.1.33 into Uruguayan localities at the bordering region. The most probable sources of viral strains introduced to Uruguay were the Southeast Brazilian region and the state of Rio Grande do Sul. Some of the viral strains introduced in Uruguayan border localities between early May and mid-July were able to locally spread and originated the first outbreaks detected outside the metropolitan region. The viral lineages responsible for Uruguayan urban outbreaks were defined by a set of between four and 11 mutations (synonymous and non-synonymous) with respect to the ancestral B.1.1.28 and B.1.1.33 viruses that arose in Brazil, supporting the notion of a rapid genetic differentiation between SARS-CoV-2 subpopulations spreading in South America. Although Uruguayan borders have remained essentially closed to non-Uruguayan citizens, the inevitable flow of people across the dry border with Brazil allowed the repeated entry of the virus into Uruguay and the subsequent emergence of local outbreaks in Uruguayan border localities. Implementation of coordinated bi-national surveillance systems is crucial to achieve an efficient control of the SARS-CoV-2 spread across this kind of highly permeable borderland regions around the world.

Highlights

The severe acute respiratory syndrome coronavirus 2 (SARSCoV-2), the causative agent of coronavirus disease 19 (COVID19), was first reported in South America on February 26, 2020 and rapidly spread through the region
2https://pangolin.cog-uk.io from 54 individuals diagnosed between May 5 and July 27 in the five Uruguayan border departments (AR, Cerro Largo (CL), RI, RO, and Treinta y Tres (TT)) and from 68 individuals diagnosed at 42 different municipalities from Rio Grande do Sul (RS) state collected between March 9 and August 16, 2020 (Figure 1A and Supplementary Table 1 in Supplementary Material Section 2)
These sequences were combined with a few SARS-CoV-2 whole-genome sequences from Uruguayan individuals diagnosed at RI (n = 5) and Montevideo (n = 1) and from Brazilian individuals sampled in RS (n = 13) retrieved from the EpiCoV database in the GISAID initiative

Summary

Introduction

The severe acute respiratory syndrome coronavirus 2 (SARSCoV-2), the causative agent of coronavirus disease 19 (COVID19), was first reported in South America on February 26, 2020 and rapidly spread through the region. South America is the second-worst affected region in the world, with more than 11 million SARS-CoV-2 cases and nearly 350,000 deaths confirmed as of December, 2020 (Worldometers, 2020). While the virus exponentially spread during the first half of 2020 in most South American countries, the rapid implementation of non-pharmaceutical interventions avoided an exponential growth of SARS-CoV-2 cases in Uruguay (Moreno et al, 2020; Valcarcel et al, 2020). Despite Uruguay’s success to control the early expansion of SARS-CoV-2, the intensive cross-border human mobility between Uruguay and neighboring countries heavily affected by the pandemic is a major concern for public health authorities, aiming to achieve long-term epidemic control. The Brazilian–Uruguayan border hosts about 170,000 people that live in twin cities located both sides of a dry border and that maintain an intense economic and social interdependence (Arnson et al, 2020)

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