Your browser doesn't support javascript.
Montrer: 20 | 50 | 100
Résultats 1 - 9 de 9
Filtre
Ajouter des filtres

Base de données
Type de document
Gamme d'année
1.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21268309

Résumé

The COVID-19 epidemic in Brazil was driven mainly by the spread of Gamma (P.1), a locally emerged Variant of Concern (VOC) that was first detected in early January 2021. This variant was estimated to be responsible for more than 96% of cases reported between January and June 2021, being associated with increased transmissibility and disease severity, a reduction in neutralization antibodies and effectiveness of treatments or vaccines, as well as diagnostic detection failure. Here we show that, following several importations predominantly from the USA, the Delta variant rapidly replaced Gamma after July 2021. However, in contrast to what was seen in other countries, the rapid spread of Delta did not lead to a large increase in the number of cases and deaths reported in Brazil. We suggest that this was likely due to the relatively successful early vaccination campaign coupled with natural immunity acquired following prior infection with Gamma. Our data reinforces reports of the increased transmissibility of the Delta variant and, considering the increasing concern due to the recently identified Omicron variant, argues for the necessity to strengthen genomic monitoring on a national level to quickly detect and curb the emergence and spread of other VOCs that might threaten global health.

2.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21266298

Résumé

Outbreaks of COVID at university campuses can spread rapidly and threaten the broader community. We describe the management of an outbreak at a Malawian university in April-May 2021 during Malawis second wave. Classes were suspended following detection of infections by routine testing and campus-wide PCR mass testing was conducted. Fifty seven cases were recorded, 55 among students, two among staff. Classes resumed 28 days after suspension following two weeks without cases. Just 6.3% of full-time staff and 87.4% of outsourced staff tested while 65% of students at the main campus and 74% at the extension campus were tested. Final year students had significantly higher positivity and lower testing coverage compared to freshmen. All viruses sequenced were beta variant and at least four separate virus introductions onto campus were observed. These findings are useful for development of campus outbreak responses and indicate the need to emphasize staff, males and senior students in testing. Article Summary LineSuccessful management of a campus outbreak using test trace and isolate approach with resumption within a month following suspension of all in-person classes. Trends in voluntary testing by gender, age and year of study that can help in formation of future management approaches.

3.
Marta Giovanetti; Svetoslav Nanev Slavov; Vagner Fonseca; Eduan Wilkinson; Houriiyah Tegally; Jose Patane; Vincent Louis Viala; Emmanuel James San; Evandra Strazza Rodrigues; Elaine Vieira Santos; Flavia Aburjaile; Joilson Xavier; Hegger Fritsch; Talita Emile Ribeiro Adelino; Felicidade Pereira; Arabela Leal; Felipe Campos de Melo Iani; Glauco de Carvalho Pereira; Cynthia Vazquez; Gladys Mercedes Estigarribia Sanabria; Elaine Cristina de Oliveira; Luiz Demarchi; Julio Croda; Rafael Dos Santos Bezerra Sr.; Loyze Paola Oliveira de Lima; Antonio Jorge Martins; Claudia Renata dos Santos Barros; Elaine Cristina Marqueze; Jardelina de Souza Todao Bernardino; Debora Botequio Moretti; Ricardo Augusto Brassaloti; Raquel de Lello Rocha Campos Cassano; Pilar Drummond Sampaio Correa Mariani; Joao Paulo Kitajima; Bibiana Santos; Rodrigo Proto Siqueira; Vlademir Vicente Cantarelli; Stephane Tosta; Vanessa Brandao Nardy; Luciana Reboredo de Oliveira da Silva; Marcela Kelly Astete Gomez; Jaqueline Gomes Lima; Adriana Aparecida Ribeiro; Natalia Rocha Guimaraes; Luiz Takao Watanabe; Luana Barbosa Da Silva; Raquel da Silva Ferreira; Mara Patricia F. da Penha; Maria Jose Ortega; Andrea Gomez de la Fuente; Shirley Villalba; Juan Torales; Maria Liz Gamarra; Carolina Aquino; Gloria Patricia Martinez Figueredo; Wellington Santos Fava; Ana Rita C. Motta Castro; James Venturini; Sandra Maria do Vale Leone de Oliveira; Crhistinne Cavalheiro Maymone Goncalves; Maria do Carmo Debur Rossa; Guilherme Nardi Becker; Mayra Marinho Presibella; Nelson Quallio Marques; Irina Nastassja Riediger; Sonia Raboni; Gabriela Mattoso; Allan D. Cataneo; Camila Zanluca; Claudia N Duarte dos Santos; Patricia Akemi Assato; Felipe Allan da Silva da Costa; Mirele Daiana Poleti; Jessika Cristina Chagas Lesbon; Elisangela Chicaroni Mattos; Cecilia Artico Banho; Livia S Sacchetto; Marilia Mazzi Moraes; Rejane Maria Tommasini Grotto; Jayme A. Souza-Neto; Mauricio L Nogueira; Heidge Fukumasu; Luiz Lehmann Coutinho; Rodrigo Tocantins Calado; Raul Machado Neto; Ana Maria Bispo de Filippis; Rivaldo Venancio da Cunha; Carla Freitas; Cassio Roberto Leonel Peterka; Cassia de Fatima Rangel Fernandes; Wildo Navegantes; Rodrigo Fabiano do Carmo Said; Maria Almiron; Carlos F Campelo de A e Melo; Jose Lourenco; Tulio de Oliveira; Edward C Holmes; Ricardo Haddad; Sandra Coccuzzo Sampaio; Maria Carolina Elias; Simone Kashima; Luiz Carlos Junior Alcantara; Dimas Tadeu Covas.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21264644

Résumé

Brazil has experienced some of the highest numbers of COVID-19 infections and deaths globally and made Latin America a pandemic epicenter from May 2021. Although SARS-CoV-2 established sustained transmission in Brazil early in the pandemic, important gaps remain in our understanding of local virus transmission dynamics. Here, we describe the genomic epidemiology of SARS-CoV-2 using near-full genomes sampled from 27 Brazilian states and an adjacent country - Paraguay. We show that the early stage of the pandemic in Brazil was characterised by the co-circulation of multiple viral lineages, linked to multiple importations predominantly from Europe, and subsequently characterized by large local transmission clusters. As the epidemic progressed, the absence of effective restriction measures led to the local emergence and international spread of Variants of Concern (VOC) and under monitoring (VUM), including the Gamma (P.1) and Zeta (P.2) variants. In addition, we provide a preliminary genomic overview of the epidemic in Paraguay, showing evidence of importation from Brazil. These data reinforce the need for the implementation of widespread genomic surveillance in South America as a toolkit for pandemic monitoring and providing a means to follow the real-time spread of emerging SARS-CoV-2 variants with possible implications for public health and immunization strategies.

4.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21259017

Résumé

Mauritius, a small island in the Indian Ocean, has had a unique experience of the SARS-CoV-2 pandemic. In March 2020, Mauritius endured a small first wave and quickly implemented control measures which allowed elimination of local transmission of SARS-CoV-2. When borders to the island reopened, it was accompanied by mandatory quarantine and testing of incoming passengers to avoid reintroduction of the virus into the community. As variants of concern (VOCs) emerged elsewhere in the world, Mauritius began using genomic surveillance to keep track of quarantined cases of these variants. In March 2021, another local outbreak occurred, and sequencing was used to investigate this new wave of local infections. Here, we analyze 154 SARS-CoV-2 viral genomes from Mauritius, which represent 12% of all the infections seem in Mauritius, these were both from specimens of incoming passengers before March 2021 and those of cases during the second wave. Our findings indicate that despite the presence of known VOCs Beta (B.1.351) and Alpha (B.1.1.7) among quarantined passengers, the second wave of local SARS-CoV-2 infections in Mauritius was caused by a single introduction and dominant circulation of the B.1.1.318 virus. The B.1.1.318 variant is characterized by fourteen non-synonymous mutations in the S-gene, with five encoded amino acid substitutions (T95I, E484K, D614G, P681H, D796H) and one deletion (Y144del) in the Spike glycoprotein. This variant seems to be increasing in prevalence and it is now present in 34 countries. This study highlights that despite having stopped the introduction of more transmissible VOCs by travel quarantines, a single undetected introduction of a B.1.1.318 lineage virus was enough to initiate a large local outbreak in Mauritius and demonstrated the need for continuous genomic surveillance to fully inform public health decisions.

5.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21258228

Résumé

While most people effectively clear SARS-CoV-2, there are several reports of prolonged infection in immunosuppressed individuals. Here we present a case of prolonged infection of greater than 6 months with shedding of high titter SARS-CoV-2 in an individual with advanced HIV and antiretroviral treatment failure. Through whole genome sequencing at multiple time-points, we demonstrate the early emergence of the E484K substitution associated with escape from neutralizing antibodies, followed by other escape mutations and the N501Y substitution found in most variants of concern. This provides support to the hypothesis of intra-host evolution as one mechanism for the emergence of SARS-CoV-2 variants with immune evasion properties.

6.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21254323

Résumé

At the end of 2020, the Network for Genomic Surveillance in South Africa (NGS-SA) detected a SARS-CoV-2 variant of concern (VOC) in South Africa (501Y.V2 or PANGO lineage B.1.351)1. 501Y.V2 is associated with increased transmissibility and resistance to neutralizing antibodies elicited by natural infection and vaccination2,3. 501Y.V2 has since spread to over 50 countries around the world and has contributed to a significant resurgence of the epidemic in southern Africa. In order to rapidly characterize the spread of this and other emerging VOCs and variants of interest (VOIs), NGS-SA partnered with the Africa Centres for Disease Control and Prevention and the African Society of Laboratory Medicine through the Africa Pathogen Genomics Initiative to strengthen SARS-CoV-2 genomic surveillance across the region.

7.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21252268

Résumé

The emergence and rapid rise in prevalence of three independent SARS-CoV-2 "501Y lineages, B.1.1.7, B.1.351 and P.1, in the last three months of 2020 prompted renewed concerns about the evolutionary capacity of SARS-CoV-2 to adapt to both rising population immunity, and public health interventions such as vaccines and social distancing. Viruses giving rise to the different 501Y lineages have, presumably under intense natural selection following a shift in host environment, independently acquired multiple unique and convergent mutations. As a consequence, all have gained epidemiological and immunological properties that will likely complicate the control of COVID-19. Here, by examining patterns of mutations that arose in SARS-CoV-2 genomes during the pandemic we find evidence of a major change in the selective forces acting on various SARS-CoV-2 genes and gene segments (such as S, nsp2 and nsp6), that likely coincided with the emergence of the 501Y lineages. In addition to involving continuing sequence diversification, we find evidence that a significant portion of the ongoing adaptive evolution of the 501Y lineages also involves further convergence between the lineages. Our findings highlight the importance of monitoring how members of these known 501Y lineages, and others still undiscovered, are convergently evolving similar strategies to ensure their persistence in the face of mounting infection and vaccine induced host immune recognition.

8.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-20248640

Résumé

Continued uncontrolled transmission of the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) in many parts of the world is creating the conditions for significant virus evolution. Here, we describe a new SARS-CoV-2 lineage (501Y.V2) characterised by eight lineage-defining mutations in the spike protein, including three at important residues in the receptor-binding domain (K417N, E484K and N501Y) that may have functional significance. This lineage emerged in South Africa after the first epidemic wave in a severely affected metropolitan area, Nelson Mandela Bay, located on the coast of the Eastern Cape Province. This lineage spread rapidly, becoming within weeks the dominant lineage in the Eastern Cape and Western Cape Provinces. Whilst the full significance of the mutations is yet to be determined, the genomic data, showing the rapid displacement of other lineages, suggest that this lineage may be associated with increased transmissibility.

9.
Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-20221143

Résumé

In March 2020, the first cases of COVID-19 were reported in South Africa. The epidemic spread very fast despite an early and extreme lockdown and infected over 600,000 people, by far the highest number of infections in an African country. To rapidly understand the spread of SARS-CoV-2 in South Africa, we formed the Network for Genomics Surveillance in South Africa (NGS-SA). Here, we analyze 1,365 high quality whole genomes and identify 16 new lineages of SARS-CoV-2. Most of these unique lineages have mutations that are found hardly anywhere else in the world. We also show that three lineages spread widely in South Africa and contributed to [~]42% of all of the infections in the country. This included the first identified C lineage of SARS-CoV-2, C.1, which has 16 mutations as compared with the original Wuhan sequence. C.1 was the most geographically widespread lineage in South Africa, causing infections in multiple provinces and in all of the eleven districts in KwaZulu-Natal (KZN), the most sampled province. Interestingly, the first South-African specific lineage, B.1.106, which was identified in April 2020, became extinct after nosocomial outbreaks were controlled. Our findings show that genomic surveillance can be implemented on a large scale in Africa to identify and control the spread of SARS-CoV-2.

SÉLECTION CITATIONS
Détails de la recherche
...