Online symptoms screening and testing of Covid-19 through RT-LAMP saliva of students and asymptomatic employees in a public school in Brazil. (preprint)

Objective To evaluate a respiratory symptoms screening system and test asymptomatic individuals (high school students and employees) at a public school in Brazil.Methods SARS-CoV-2 reverse transcription loop-mediated isothermal amplification (RT-LAMP) of saliva samples was performed weekly.Results A total of 969 samples were tested (mean of 108 tests per week). No asymptomatic participants tested positive for COVID-19, and no cases of COVID-19 transmission occurred at school despite the high transmissibility of the Delta variant, the local predominant variant at the time of the study.Conclusion Implementation of an online system of respiratory symptom screening and testing of COVID-19 through saliva in asymptomatic individuals is a feasible, low-cost and practical option to be used, especially in low-income countries.

Impact of COVID-19 RT-PCR Testing of Asymptomatic Health Care Workers on Absenteeism and Hospital Transmission During the Pandemic (preprint)

Reducing the transmission of SARS-CoV-2 from asymptomatic and pre-symptomatic patients is critical in controlling the circulation of the virus. This study evaluated the prevalence of RT-PCR positivity in serial tests (every 20 days) in 429 asymptomatic health care workers (HCW) and its impact on absenteeism from May to August 2020. Asymptomatic HCW from a COVID-19 reference hospital in Campinas (1.2 million inhabitants), Brazil, were tested, screened, and placed on leave. A time-series segmented regression of weekly absenteeism rates was used, and cases of infection among hospitalized patients were analyzed. Viral gene sequencing and phylogenetic analysis were performed on samples gathered from professionals who had a positive result. A significant decrease in absenteeism was detected 3–4 weeks after the intervention at a time of increased transmission within the city. The prevalence of RT-PCR positivity among asymptomatic professionals was 17.3%. Phylogenetic analyses of 59 samples detected nine clusters, two of them strongly suggestive of intra-hospital transmission with strains (75% B.1.1.28) circulating in the region during this period.Testing and placing asymptomatic professionals on leave contributed to control strategy for COVID-19 transmission in the hospital environment, and in reducing positivity and absenteeism, which directly influences the quality of care and exposes professionals to an extra load of stress.

Genetic risk factors and Covid-19 severity in Brazil: results from BRACOVID Study (preprint)

The Covid-19 pandemic has changed the paradigms for disease surveillance and rapid deployment of scientific-based evidence for understanding disease biology, susceptibility, and treatment. We have organized a large-scale genome-wide association study in Sars-Cov-2 infected individuals in Sao Paulo, Brazil, one of the most affected areas of the pandemic in the country, itself one of the most affected in the world. Here we present the results of the initial analysis in the first 5,233 participants of the BRACOVID study. We have conducted a GWAS for Covid-19 hospitalization enrolling 3533 cases (hospitalized Covid-19 participants) and 1700 controls (non-hospitalized Covid-19 participants). Models were adjusted by age, sex and the 4 first principal components. A meta-analysis was also conducted merging BRACOVID hospitalization data with the Human Genetic Initiative (HGI) Consortia results. BRACOVID results validated most loci previously identified in the HGI meta-analysis. In addition, no significant heterogeneity according to ancestral group within the Brazilian population was observed for the two most important Covid-19 severity associated loci: 3p21.31 and Chr21 near IFNAR2. Using only data provided by BRACOVID a new genome-wide significant locus was identified on Chr1 near the genes DSTYK and RBBP5. The associated haplotype has also been previously associated with a number of blood cell related traits and might play a role in modulating the immune response in Covid-19 cases.

Clinical Characteristics of COVID-19 by SARS-CoV-2 Gamma Variant in Vaccinated and Non-Vaccinated Healthcare Workers (preprint)

Background: The Gamma variant has been considered the predominant SARS-CoV-2 lineage in Brazil during the first half of 2021. We aimed to characterise the clinical presentation of COVID-19 caused by the Gamma variant in comparison with strains that are not variants of concern (non-VoC).Method: We performed a prospective cohort study including symptomatic COVID-19 cases among healthcare workers from January 22 to May 15, 2021. Positive samples for SARS-CoV-2 RT-PCR underwent whole genome sequencing. COVID-19 symptoms, caused by the Gamma variant or non-VoC, and risk factors for Gamma variant infection were evaluated using multiple logistic regression analyses.Findings: We included 423 COVID-19 cases, of which 415 (98%) with mild disease. One hundred and seventy-five (41%) patients had been fully immunised, of which 173/175 (99%) had received CoronaVac. There were 313 (74%) Gamma variant cases and 110 (26%) non-VoC cases. Hyposmia/anosmia and dysgeusia were present in 129 (30%) and 108 (26%) of cases, respectively. Lower frequencies of hyposmia/anosmia (OR=0.304, p <0.001) and dysgeusia (OR=0.385, p =0.011) were the only symptoms significantly associated with Gamma variant infection. COVID-19 immunisation, previous COVID-19 and age were not associated with Gamma variant infection.Interpretation: The increase in Gamma variant cases should raise the awareness that COVID-19 may present more often with cold-like symptoms because of a decreased frequency of hyposmia/anosmia and dysgeusia.Funding: Supported by the Itau Unibanco “Todos pela saúde” program”.Declaration of Interest: None to declare. Ethical Approval: This study was approved by the Hospital’s Ethics Committee (CAAE: 42708721.0.0000.0068).

A novel RT-LAMP workflow for rapid salivary diagnostics of COVID-19 and effects of age, gender and time from symptom onset (preprint)

Objectives: Rapid diagnostics is pivotal to curb SARS-CoV-2 transmission, and saliva has emerged as a practical alternative to naso/oropharyngeal (NOP) specimens. We aimed to develop a direct RT-LAMP workflow for viral detection in saliva, and to provide more information regarding its potential in COVID-19 diagnostics. Methods: Clinical and contrived specimens were used to screen/optimize formulations and sample processing protocols. Salivary viral load was determined in symptomatic patients to evaluate clinical performance (n = 90) and to characterize saliva based on age, gender and time from onset of symptoms (n = 49). Results: The devised workflow achieved 93.2% sensitivity, 97% specificity, and 0.895 Kappa for salivas containing >102 copies/L. Further analyses in saliva showed peak viral load in the first days of symptoms and lower viral loads in females, particularly among young individuals (<38 years). NOP RT-PCR data did not yield relevant associations. Conclusions: This novel saliva RT-LAMP workflow can be applied to point-of-care testing. This work reinforces that saliva better correlates with transmission dynamics than NOP specimens, and reveals gender differences that may reflect higher transmission by males. To maximize detection, testing should be done immediately after symptom onset, especially in females.

Understanding the Potential Role of Therapeutics in Preventing Deaths Due to COVID-19: A Modelling Analysis (preprint)

Background: The unprecedented public health impact of the COVID-19 pandemic has motivated a rapid search for potential therapeutics, with some key successes. However, the potential impact of current and proposed treatments, and consequently research and procurement priorities, have not been clear. Methods: First, we used a model of SARS-CoV-2 transmission, COVID-19 disease and clinical care pathways to explore the potential impact of dexamethasone - the main treatment currently for hospitalised COVID-19 patients - under scenarios varying: i) healthcare capacity, ii) epidemic trajectories; and iii) the efficacy of dexamethasone in the absence of supportive care. We then fit the model to the observed epidemic trajectory to-date in 165 countries and analysed the potential future impact of dexamethasone in different countries, regions, and country-income strata. Finally, we constructed hypothetical profiles of novel therapeutics based on current trials, and compared the potential impact of each under different circumstances. In each case, the outcome of interest was the number of COVID-19 deaths averted in scenarios with the therapeutic compared to scenarios without. Findings: We find the potential benefit dexamethasone is severely limited in settings where healthcare capacity is lowest or where uncontrolled epidemics result in hospitals being overwhelmed. As such, it may avert 22% of deaths in high-income countries but only 8% in low-income countries (assuming R=1.35). However, therapeutics for different patient populations (in particular, those not in hospital and early in the course of infection) and types of benefit (in particular, reducing disease severity or infectiousness) could have much greater benefits. Such therapeutics would have particular value in resource-poor settings facing large epidemics, even if the efficacy or achievable coverage of such therapeutics is lower in comparison to other types. Interpretation: People in low-income countries will benefit the least from advances in the treatment of COVID-19 to date, which have focussed on hospitalised-patients with adequate access to supportive care. Therapeutics that can feasibly be delivered to those earlier in the course of infection that reduce the need for healthcare or reduce infectiousness could have much greater impact. Such therapeutics may be feasible and research into their efficacy and means of delivery should be a priority. Funding: None to declare. Declaration of Interest: None to declare.

Evaluating burnout among health workers routinely screened for SARS-CoV-2. (preprint)

Background: Healthcare workers (HW) are a vulnerable group to develop burnout during the COVID-19 pandemic. The aims of this study were to evaluate the perception of HW about the antibody test, and, secondarily, the prevalence of burnout and factors associated with burnout among HW who took the test.Methods: In this cross-sectional study, we evaluated burnout among HW in a 600-bed building entirely dedicated to COVID-19 inpatients care at Hospital das Clinicas (HC), located in São Paulo, Brazil. The HW answered an online questionnaire that included questions on burnout, a single-item scale based on the Maslach Burnout Inventory; demographic data, professional category, type of Protective Personal Equipment (PPE) used, distancing from social support; and emotional reactions to their serology result. Bivariate and multivariate analyses were done to evaluate the risk of burnout.Outcomes: Among 4,417 HW tested, 528 (12.0%) were positive for SARS-CoV-2 and 1,945 answered the questionnaire. Burnout was reported by 308 (15.8%); anxiety, tenseness, and depression associated with COVID-19 were reported by 344 (17.7%); 292 (15.1%); and 181(9.3%) of the participants, respectively. The risk factors for burnout were: being a physician [adjOR:1.604;(95%CI 1.604-1.080;p=0.019)]; a physiotherapist [adjOR:2.047;(95%CI:1.285–3.261;p=0.003)]; perceiving a decrease in public safety[adjOR:1.983;(95%CI:1.229–3.199;p=0.005)]; anxiety [adjOR:2.721;(95%CI:1.812–4.085;p=<0.001)], and depression associated with COVID-19[adjOR:2.071;(95%CI:1.308–3.279;p=0.002)]; and having negative feeling towards had a previously negative SARS-CoV-2 serology[adjOR:1,989;(95%CI:1.484-2.664; p<0.001)].Interpretation: Routine serological testing was one of the strategies used in our hospital to promote the well-being of HW. We observed that those who had negative feeling regarding testing negative to COVID-19 in previous serologies were at higher risk of burnout, suggesting that the risk of contracting the disease is a major stressor for HW.

Are Mobile Phones part of the chain of transmission of SARS-CoV-2 in the hospital? (preprint)

SARS-CoV-2 cross-transmission has become an concern in hospitals. We investigate healthcare workers(HCWs) knowledge about SARS-CoV-2 cross-transmission and conceptions whether the virus can remain on HCWs mobile phones(MPs) and be part of the chain of transmission. A cross-sectional study was conducted at a COVID-19 Intensive Care Unit of a teaching-hospital. Fifty-one MPs were swabbed and a questionnaire about hand hygiene and MP use and disinfection was applied after an educational campaign. Although most of HCWs believed on the importance of cross-transmission and increased hand hygiene adhesion and MP disinfection during the pandemic, SARS-CoV-2 RNA was detected in two MPs(culture of the samples was negative). Implementation of official hospital policies to guide HCWs regarding disinfection and care of personal MP are needed.

EVALUATION OF ELEVEN IMMUNOCHROMATOGRAPHIC ASSAYS FOR SARS-CoV-2 DETECTION: INVESTIGATING DENGUE CROSS-REACTION (preprint)

Background: COVID-19 disease (Coronavirus disease 2019) caused by SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) is widespread worldwide, affecting more than 11 million people globally (July 6th, 2020). Diagnostic techniques have been studied in order to contain the pandemic. Immunochromatographic (IC) assays are feasible and low cost alternative for monitoring the spread of COVID-19 in the population. Methods: Here we evaluate the sensitivity and specificity of eleven different immunochromatografic tests in 98 serum samples from confirmed cases of COVID-19 through RT-PCR and 100 negative serum samples from blood donors collected in February 2019. Considering the endemic situation of Dengue in Brazil, we also evaluated the cross-reactivity with Dengue using 20 serum samples from patients with confirmed diagnosis for Dengue collected in early 2019 through four different tests. Results: Our results demonstrated agreement between immunochromatographic assays and RT-PCR, especially after 10 days since the onset of symptoms. The evaluation of IgG and IgM antibodies combined demonstrated a strong level of agreement (0.85) of IC assays and RT-PCR. It was observed cross-reactivity between Dengue and COVID-19 using four different IC assays for COVID-19 diagnosis. The specificity of IC assays to detected COVID-19 IgM antibodies using Dengue serum samples varied from 80% to 85%; the specificity of IgG detection was 100% and total antibody was 95%. Conclusions: We found high sensitivity, specificity and good agreement of IC assays, especially after 10 days onset of symptoms. However, we detected cross-reactivity between Dengue and COVID-19 mainly with IgM antibodies demonstrating the need for better studies about diagnostic techniques for these diseases.

Evolution and epidemic spread of SARS-CoV-2 in Brazil (preprint)

Brazil currently has one of the fastest growing SARS-CoV-2 epidemics in the world. Due to limited available data, assessments of the impact of non-pharmaceutical interventions (NPIs) on virus transmission and epidemic spread remain challenging. We investigate the impact of NPIs in Brazil using epidemiological, mobility and genomic data. Mobility-driven transmission models for Sao Paulo and Rio de Janeiro cities show that the reproduction number (Rt) reached below 1 following NPIs but slowly increased to values between 1 to 1.3 (1.0 - -1.6). Genome sequencing of 427 new genomes and analysis of a geographically representative genomic dataset from 21 of the 27 Brazilian states identified >100 international introductions of SARS-CoV-2 in Brazil. We estimate that three clades introduced from Europe emerged between 22 and 27 February 2020, and were already well-established before the implementation of NPIs and travel bans. During this first phase of the epidemic establishment of SARS-CoV-2 in Brazil, we find that the virus spread mostly locally and within-state borders. Despite sharp decreases in national air travel during this period, we detected a 25% increase in the average distance travelled by air passengers during this time period. This coincided with the spread of SARS-CoV-2 from large urban centers to the rest of the country. In conclusion, our results shed light on the role of large and highly connected populated centres in the rapid ignition and establishment of SARS-CoV-2, and provide evidence that current interventions remain insufficient to keep virus transmission under control in Brazil.