SARS-CoV-2 PCR Persistence and Duration of COVID-19 Symptoms in Health Professionals (preprint)

Background and Objectives: Most individuals infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are asymptomatic or have mild symptoms of COVID-19, which usually resolve after few days. Regardless of symptoms, infected people can transmit the virus to others especially on the first days of infection. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) is used to confirm SARS-CoV-2 infection; some individuals show persistent PCR-positivity after recovering from COVID-19. In this study, 12 individuals who showed persistence of COVID-19 symptoms and of SARS-CoV-2 PCR-positivity were followed-up. Methods: nasopharyngeal samples were collected for SARS-CoV-2 detection by RT-qPCR; clinical and epidemiological data were analyzed. Results: that persistence of SARS-CoV-2 PCR positivity was associated with duration of symptoms (rs 0.81338), which varied between one and 49 days, with 75% of the individuals reporting symptoms for more than two weeks; 83.33% of cases remained positive after two weeks of onset of symptoms, despite decreases in viral load. Conclusion: neither RT-qPCR test nor a symptom-based approach alone are sufficient to evaluate discontinuation of patient isolation; other factors such as viral loads and symptom severity should also be considered. Additional studies are needed to understand how RT-PCR-positivity is related to symptoms and the risk of viral transmission, and to better support isolation guidelines.

Multi-site validation of an amplicon-based sequencing approach for human monkeypox virus (preprint)

The 2022 multi-country monkeypox outbreak concurrent with the ongoing COVID-19 pandemic has further highlighted the need for genomic surveillance and pathogen whole genome sequencing. While metagenomic sequencing approaches have been used to sequence many of the early human monkeypox virus infections, these methods are resource intensive and require samples with high viral DNA concentrations. Given the atypical clinical presentation of cases associated with the current outbreak and uncertainty regarding viral load across both the course of infection and anatomical body sites, there is an urgent need for a more sensitive and broadly applicable sequencing approach. Amplicon-based sequencing (PrimalSeq) was initially developed for sequencing of Zika virus, and later adapted as the main sequencing approach for SARS-CoV-2. Here, we used PrimalScheme to develop a primer scheme for human monkeypox virus that can be used with many sequencing and bioinformatics pipelines implemented during the COVID-19 pandemic. We sequenced clinical samples that tested presumptive positive for monkeypox virus with amplicon-based and metagenomic sequencing approaches. Upon comparison, we found notably higher genome coverage across the virus genome, particularly in higher PCR cycle threshold (lower DNA titer) samples, with minimal amplicon drop-outs, in using the amplicon-based sequencing approach. By sending out primer pool aliquots to laboratories across the United States and internationally, we validated the primer scheme in 12 public health laboratories with their established Illumina or Oxford Nanopore Technologies sequencing workflows and with different sample types across a range of Ct values. Our findings suggest that amplicon-based sequencing increases the success rate across a wider range of viral DNA concentrations, with the PCR Ct value threshold at which laboratories were able to achieve 80% genome coverage at 10X ranging between Ct 25-33. Therefore, it increases the number of samples where near-complete genomes can be generated and it provides a cost-effective and widely applicable alternative to metagenomics for continued human monkeypox virus genomic surveillance. Importantly, we show that the human monkeypox virus primer scheme can be used with currently implemented amplicon-based SARS-CoV-2 sequencing workflows, with minimal change to the protocol.

Unusual SARS-CoV-2 intra-host diversity reveals lineages superinfection (preprint)

The SARS-CoV-2 has infected almost 200 million people worldwide by July 2021 and the pandemic has been characterized by infection waves of viral lineages showing distinct fitness profiles. The simultaneous infection of a single individual by two distinct SARS-CoV-2 lineages provides a window of opportunity for viral recombination and the emergence of new lineages with differential phenotype. Several hundred SARS-CoV-2 lineages are currently well characterized but two main factors have precluded major coinfection/codetection analysis thus far: i) the low diversity of SARS-CoV-2 lineages during the first year of the pandemic which limited the identification of lineage defining mutations necessary to distinguish coinfecting viral lineages; and the ii) limited availability of raw sequencing data where abundance and distribution of intrasample/intrahost variability can be accessed. Here, we have put together a large sequencing dataset from Brazilian samples covering a period of 18 May 2020 to 30 April 2021 and probed it for unexpected patterns of high intrasample/intrahost variability. It enabled us to detect nine cases of SARS-CoV-2 coinfection with well characterized lineage-defining mutations. In addition, we matched these SARS-CoV-2 coinfections with spatio-temporal epidemiological data confirming their plausibility with the co-circulating lineages at the timeframe investigated. These coinfections represent around 0.61% of all samples investigated. Although our data suggests that coinfection with distinct SARS-CoV-2 lineages is a rare phenomenon, it is likely an underestimation and coinfection rates warrants further investigation. DATA SUMMARYThe raw fastq data of codetection cases are deposited on gisaid.org and correlated to gisaid codes: EPI_ISL_1068258, EPI_ISL_2491769, EPI_ISL_2491781, EPI_ISL_2645599, EPI_ISL_2661789, EPI_ISL_2661931, EPI_ISL_2677092, EPI_ISL_2777552, EPI_ISL_3869215. Supplementary data are available on https://doi.org/10.6084/m9.figshare.16570602.v1. The workflow code used in this study is publicly available on: https://github.com/dezordi/IAM_SARSCOV2.

SARS-CoV-2 introduction and lineage dynamics across three epidemic peaks in Southern Brazil: massive spread of P.1 (preprint)

ABSTRACT Background Genomic surveillance of SARS-CoV-2 is paramount for understanding viral dynamics, contributing to disease control. This study analyzed SARS-CoV-2 genomic diversity in Rio Grande do Sul (RS), Brazil, including the first case of each Regional Health Coordination and cases from three epidemic peaks. Methods Ninety SARS-CoV-2 genomes from RS were sequenced and analyzed against SARS-CoV-2 datasets available in GISAID for phylogenetic inference and mutation analysis. Results SARS-CoV-2 lineages among the first cases in RS were B.1 (33.3%), B.1.1.28 (26.7%), B.1.1 (13.3%), B.1.1.33 (10.0%), and A (6.7%), evidencing SARS-CoV-2 introduction by both international origin and community-driven transmission. We found predominance of B.1.1.33 (50.0%) and B.1.1.28 (35.0%) during the first epidemic peak (July–August, 2020), emergence of P.2 (55.6%) in the second peak (November–December, 2020), and massive spread of P.1 and related sequences (78.4%), such as P.1-like-II, P.1.1 and P.1.2 in the third peak (February–April, 2021). Eighteen novel mutation combinations were found among P.1 genomes, and 22 different spike mutations and/or deletions among P.1 and related sequences. Conclusions This study shows the dispersion of SARS-CoV-2 lineages in Southern Brazil, and describes SARS-CoV-2 diversity during three epidemic peaks, highlighting the spread of P.1 and the high genetic diversity of currently circulating lineages. Genomic monitoring of SARS-CoV-2 is essential to guide health authorities’ decisions to control COVID-19 in Brazil. Summary Ninety SARS-CoV-2 genomes from Rio Grande do Sul, Brazil, were sequenced, including the first cases from 15 State Health Coordination regions and samples from three epidemic peaks. Phylogenomic inferences showed SARS-CoV-2 lineages spread, revealing its genomic diversity.

Identification of SARS-CoV-2 P.1-related lineages in Brazil provides new insights about the mechanisms of emergence of Variants of Concern (preprint)

One of the most remarkable features of the SARS-CoV-2 Variants of Concern (VOC) is the unusually large number of mutations they carry. However, the specific factors that drove the emergence of such variants since the second half of 2020 are not fully resolved. In this study, we described a new SARS-CoV-2 lineage provisionally designated as P.1-like-II that, as well as the previously described lineage P.1-like-I, shares several lineage-defining mutations with the VOC P.1 circulating in Brazil. Reconstructions of P.1 ancestor sequences demonstrate that the entire constellation of mutations that define the VOC P.1 did not accumulate within a single long-term infected individual, but was acquired by sequential addition during interhost transmissions. Our evolutionary analyses further estimate that P.1-ancestors strains carrying half of the P.1-lineage-defining mutations, including those at the receptor-binding domain of the Spike protein, circulated cryptically in the Amazonas state since August 2020. This evolutionary pattern is consistent with the hypothesis that partial human population immunity acquired from natural SARS-CoV-2 infections during the first half of 2020 might have been the major driving force behind natural selection that allowed VOCs' emergence and worldwide spread. These findings also support a long lag-time between the emergence of variants with key mutations of concern and expansion of the VOC P.1 in Brazil.

Epidemiological investigation reveals local transmission of SARS-CoV-2 lineage P.1 in Southern Brazil (preprint)

Since its detection in December of 2020, the SARS-CoV2 lineage P.1, descendent of B.1.1.28 lineage, has been identified in several places in Brazil and abroad. This Variant of Concern was considered highly prevalent in Northern Brazil and now is rapidly widening its geographical range. In this short communication, we present epidemiological and genomic information of the first case of P1 lineage in Rio Grande do Sul state, in a patient with no reported travel history and a tracked transmission chain. These findings occurred in a tourist destination representing an important hub receiving tourists from diverse places.