An accurate and rapid diagnosis of COVID-19 is an effective strategy for pandemic control, allowing disease screening and timely therapeutic intervention. We analyzed scientific reports about rapid tests for the diagnosis of COVID-19 to assess their reliability parameters. Medical Subject Headings terms or keywords related to point-of-care and rapid diagnostic testing for SARS-CoV-2 and COVID-19 were searched in data published from November 2020 to November 2021 in PubMed and Google Scholar databases. Notable differences were observed in sensitivity among direct tests that used different samples, and good accuracy was reported in a significant number of studies (>80%). Pediatric samples and samples with high Ct values (RT-PCR) had suboptimal sensitivity (range 45.4% to 66%). Further, a lack of sensitivity (<46.2%) was observed in point-of-care tests and in rapid diagnostic tests for antibody detection in the first days after infection, with increasing values in postinfection analysis (>60%). For serological detection of IgM or Antigen rapid diagnostic tests, no cross-reactivity was found with other coronaviruses. Therefore, although these tests are very important in facing the pandemic, they still need to be improved to test cross-reactivity against other pathogens, especially against other coronaviruses.

Arthropods transmit arboviruses via mosquito and tick bites to humans and other animals. The genus flavivirus, which causes diseases, sequelae, and thousands of deaths, mainly in developing and underdeveloped countries, is among the arboviruses of interest to public health. Given the importance of early and accurate diagnosis, this review analyzes the methods of direct detection of flaviviruses, such as reverse transcription loop-mediated isothermal amplification, microfluidics, localized surface plasmon resonance, and surface-enhanced Raman scattering, and presents the advantages, disadvantages, and detection limits identified in studies reported in the literature for each methodology. Among the different methods available, it is essential to balance four fundamental indicators to determine the ideal test: good sensitivity, high specificity, low false positive rate, and rapid results. Among the methods analyzed, reverse transcription loop-mediated isothermal amplification stands out, owing to result availability within a few minutes, with good sensitivity and specificity; in addition, it is the best-characterized methodology.

SARS-CoV-2 mutations and where to find them: An in silico perspective of structural changes and antigenicity of the Spike proteinThe recent emergence of a novel coronavirus (SARS-CoV-2) is causing a severe global health threat characterized by severe acute respiratory syndrome . At the moment, there is no specific treatment for this disease, and vaccines are still under development. The structural protein Spike is essential for virus infection and has been used as the main target for vaccine and serological diagnosis test development. We analysed 2363 sequences of the Spike protein from SARS-CoV-2 isolates and identified variability in 44 amino acid residues and their worldwide distribution in all continents. We used the three-dimensional structure of the homo-trimer model to predict conformational epitopes of B-cell, and sequence of Spike protein Wuhan-Hu-1 to predict linear epitopes of T-Cytotoxic and T-Helper cells. We identified 45 epitopes with amino acid variations. Finally, we showed the distribution of mutations within the epitopes.Our findings can help researches to identify more efficient strategies for the development of vaccines, therapies, and serological diagnostic tests based on the Spike protein of Sars-Cov-2.

1 perspective of structural changes and antigenicity of the Spike protein 2 The recent emergence of a novel coronavirus (SARS-CoV-2) is causing a severe 3 global health threat around the world characterized by severe acute respiratory 4 syndrome (Covid-19). At the moment, there is no specific treatment for this 5 disease and vaccines are still under development. The structural protein Spike is 6 essential for virus infection and has been used as the main target for vaccine and 7 serological diagnosis test development. We analysed 2363 sequences of the Spike 8 protein from SARS-CoV-2 isolates and identified variability in 44 amino acid 9 residues and their worldwide distribution in all continents. We use the three-10 dimensional structure of the homo-trimer model for epitope predictions of B-cell, 11 T-Cytotoxic and T-Helper cells. A total of 45 epitopes with amino acids variation 12 were identified. Finally, we show the distribution of mutations within the 13 epitopes. Our findings can help researches to identify more efficient strategies for 14 the development of vaccines, therapies and serological diagnostic tests based on 15 the Spike protein of Sars-Cov-2.16

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