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Uruguay was able to control the viral dissemination during the first nine months of the SARS-CoV-2 pandemic. Unfortunately, towards the end of 2020, the number of daily new cases exponentially increased. Herein we analyzed the country-wide genetic diversity of SARS-CoV-2 between November, 2020 and April, 2021. Our findings identified that the most prevalent viral variant during late 2020 was a B.1.1.28 sublineage carrying mutations Q675H+Q677H in the viral Spike, now designated as lineage P.6. This new lineage P.6 probably arose around November 2020, in Montevideo, Uruguays capital department and rapidly spread to other Uruguayan departments, with evidence of further local transmission clusters, also spread sporadically to the USA and Spain. The Q675H and Q677H mutations are in the proximity of the polybasic cleavage site at the S1/S2 boundary and also arose independently in many SARS-CoV-2 lineages circulating worldwide. Although the lineage P.6 was replaced by the Variant of Concern (VOC) P.1 as the predominant viral strain in Uruguay since April 2021, the monitoring of the concurrent emergence of Q675H+Q677H in VOCs should be of worldwide interest.
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We developed a genomic surveillance program for real-time monitoring of SARS-CoV-2 variants of concern in Uruguay. Here, we present the first results, including the proposed qPCR-VOC method, the general workflow and the report of the introduction and community transmission of the VOC P.1 in Uruguay in multiple independent events.
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BackgroundUruguay is one of the few countries in the Americas that successfully contained the 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 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. MethodsUsing 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. FindingsPhylogenetic 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 suburban outbreaks were defined by a set of between four and 11 mutations (synonymous and non-synonymous) 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. InterpretationAlthough 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 are crucial to achieve an efficient control of the SARS-CoV-2 spread across this kind of highly permeable borderland regions around the world. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSSince the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causative agent of coronavirus disease 19 (COVID-19), was first detected in South America on February 26, 2020, it has rapidly spread through the region, causing nearly 350,000 deaths by December, 2020. In contrast to most American countries, Uruguay avoided an early exponential growth of SARS-CoV-2 cases and during the first six months of the pandemic it registered the lowest incidence of SARS-CoV-2 cases and deaths among South American countries. The intensive cross-border human mobility through the [~]1,100 km uninterrupted dry frontier between Uruguay and Brazil, might poses a major challenge for long-term control of the epidemic in Uruguay. Previous genomic studies conducted in Uruguay have analyzed sequences mostly sampled at the capital city, Montevideo, and detected prevalent SARS-CoV-2 lineages different from those described in Brazil, thus finding no evidence of frequent viral exchanges between these countries. Added value of this studyHere we present the first genomic study of SARS-CoV-2 strains detected in different Uruguayan and Brazilian localities along the bordering region. The samples analyzed include 30% (n = 59) of all laboratory confirmed SARS-CoV-2 cases from Uruguayan departments at the Brazilian border between March and July, 2020, as well as 68 SARS-CoV-2 sequences from individuals diagnosed in the southernmost Brazilian state of Rio Grande do Sul between March and August, 2020. We demonstrate that SARS-CoV-2 viral lineages that widely spread in the Southeastern Brazilian region (B.1.1.28 and B.1.1.33) were also responsible for most viral infections in Rio Grande do Sul and neighboring Uruguayan localities. We further uncover that major outbreaks detected in Uruguayan localities bordering Brazil in May and June, 2020, were originated from two independent introduction events of the Brazilian SARS-CoV-2 lineage B.1.1.33, unlike previous outbreaks in the Uruguayan metropolitan region that were seeded by European SARS-CoV-2 lineages. Implications of all the available evidenceOur findings confirm that although Uruguayan borders have remained essentially closed to non-Uruguayan citizens, dissemination of SARS-CoV-2 across the Uruguayan-Brazilian frontier was not fully suppressed and had the potential to ignite local transmission chains in Uruguay. These findings also highlight the relevance of implementing bi-national public health cooperation workforces combining epidemiologic and genomic data to monitor the viral spread throughout this kind of highly permeable dry frontiers around the world.
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BackgroundSouth America has become the new epicenter of the COVID-19 pandemic with more than 1.1M reported cases and >50,000 deaths (June 2020). Conversely, Uruguay stands out as an outlier managing this health crisis with remarkable success. MethodsWe developed a molecular diagnostic test to detect SARS-CoV-2. This methodology was transferred to research institutes, public hospitals and academic laboratories all around the country, creating a "COVID-19 diagnostic lab network". Uruguay also implemented active epidemiological surveillance following the "Test, Trace and Isolate" (TETRIS) strategy coupled to real-time genomic epidemiology. ResultsThree months after the first cases were detected, the number of positive individuals reached 826 (23 deaths, 112 active cases and 691 recovered). The Uruguayan strategy was based in a close synergy established between the national health authorities and the scientific community. In turn, academia rapidly responded to develop national RT-qPCR tests. Consequently, Uruguay was able to perform [~]1,000 molecular tests per day in a matter of weeks. The "COVID-19 diagnostic lab network" performed more than 54% of the molecular tests in the country. This, together with real- time genomics, were instrumental to implement the TETRIS strategy, helping to contain domestic transmission of the main outbreaks registered so far. ConclusionsUruguay has successfully navigated the first trimester of the COVID-19 health crisis in South America. A rapid response by the scientific community to increase testing capacity, together with national health authorities seeking out the support from the academia were fundamental to successfully contain, until now, the COVID-19 outbreak in the country.
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BackgroundAfter its emergence in China in December 2019, the new coronavirus disease (COVID-19) caused by SARS-CoV-2, has rapidly spread infecting more than 3 million people worldwide. South America is among the last regions hit by COVID-19 pandemic. In Uruguay, first cases were detected on March 13 th 2020 presumably imported by travelers returning from Europe. MethodsWe performed whole-genome sequencing of 10 SARS-CoV-2 from patients diagnosed during the first week (March 16th to 19th) of COVID-19 outbreak in Uruguay. Then, we applied genomic epidemiology using a global dataset to reconstruct the local spatio-temporal dynamics of SARS-CoV-2. ResultsOur phylogeographic analysis showed three independent introductions of SARS-CoV-2 from different continents. Also, we evidenced regional circulation of viral strains originally detected in Spain. Introduction of SARS-CoV-2 in Uruguay could date back as early as Feb 20th. Identification of specific mutations showed rapid local genetic differentiation. ConclusionsWe evidenced early independent introductions of SARS-CoV-2 that likely occurred before first cases were detected. Our analysis set the bases for future genomic epidemiology studies to understand the dynamics of SARS-CoV-2 in Uruguay and the Latin America and the Caribbean region.
