IMPACT OF THE COVID-19 PANDEMIC ON CERVICAL CANCER SCREENING IN SÃO PAULO STATE, BRAZIL.

INTRODUCTION: The early identification of precursor lesions followed by appropriate treatment prevents development of cervical cancer and its consequences OBJECTIVE: The present study evaluated the influence of the Covid-19 pandemic on cervical cancer screening by comparing the quantity of tests to detect cervical cellular changes performed in Sao Paulo state in 2019, prior to the detection of SARS-CoV-2 in Brazil, to the first (2020) and second (2021) years following its appearance. MATERIALS AND METHODS: Data from Fundação Oncocentro de São Paulo (FOSP), the agency that analyses approximately 220,000 Pap tests annually, was reviewed. RESULTS: A median of 1835 Papanicolaou (Pap) tests were performed in 55 municipalities in 2019. This was reduced to 815 tests in 2020, a 56% decrease (p = 0.0026). In 2021, the median number was 1745, a 53% increase over 2020 levels (p = 0.0233). The 26 municipalities with >1000 tests in 2020 had a median reduction from 4433 in 2019 to 2580 in 2020 (p = 0. 0046). The 29 municipalities with <1000 tests had a median reduction from 951 in 2019 to 554 in 2020 (p < 0.0001). There was a 44% reduction in the number of follow-up cytological evaluations from 2019 to 2020, followed by a 30% increase the following year. However, the percentage of women with a normal finding or with any abnormality remained unchanged. The findings from a histological evaluation of women in Sao Paulo city indicated that the percent of cases positive for CIN-1 (p<0.0410) and CIN-3 (p<0.0012) increased in 2020 and 2021 as compared to 2019 levels. CONCLUSION: A reduction in testing for cervical cancer in the first year of the Covid-19 pandemic, accompanied by an elevated incidence of precancerous lesions in each of the first two years following its initiation, may portend a subsequent increased occurrence of cervical cancer in Brazil.

Characterization of Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant Shedding and Predictors of Viral Culture Positivity on Vaccinated Healthcare Workers With Mild Coronavirus Disease 2019.

In this prospective cohort of 30 vaccinated healthcare workers with mild Omicron variant infection, we evaluated viral culture, rapid antigen test (RAT), and real-time reverse-transcription polymerase chain reaction (RT-PCR) of respiratory samples at days 5, 7, 10, and 14. Viral culture was positive in 46% (11/24) and 20% (6/30) of samples at days 5 and 7, respectively. RAT and RT-PCR (Ct ≤35) showed 100% negative predictive value (NPV), with positive predictive values (PPVs) of 32% and 17%, respectively, for predicting viral culture positivity. A lower RT-PCR threshold (Ct ≤24) improved culture prediction (PPV = 39%; NPV = 100%). Vaccinated persons with mild Omicron infection are potentially transmissible up to day 7. RAT and RT-PCR might be useful tools for shortening the isolation period.

CARACTERIZAÇÃO DA INFECTIVIDADE DA VARIANTE ÔMICRON E PREDITORES DE POSITIVIDADE DE CULTURA VIRAL EM PROFISSIONAIS DE SAÚDE COM COVID-19 LEVE

Introdução A variante Ômicron do vírus SARS-CoV-2 (B.1.1.529) foi designada uma variante preocupante (VOC) devido à alta transmissibilidade e capacidade de escapar da imunidade natural e induzida por vacina. Objetivo Caracterizar a duração da infectividade da variante Ômicron em indivíduos vacinados com sintomas leves de COVID-19. Método Estudo transversal com 30 indivíduos vacinados com COVID-19 para avaliar a duração da infectividade da Ômicron comparando o isolamento viral com o teste rápido de antígeno (RAT) e os valores de Ct da reação em cadeia da polimerase em tempo real (RT-PCR) de amostras respiratórias nos dias 5, 7, 10 e 14 a partir do início dos sintomas. Resultados O crescimento viral foi observado em 46% (11/24) das amostras dos indivíduos vacinados no dia 5 dos sintomas e 20% (6/30) no dia 7, nenhuma amostra teve isolamento viral no dia 10. A carga de RNA viral permaneceu detectável em 97% (29/30) e 57% (17/30) dos participantes nos dias 10 e 14, respectivamente. Entre as amostras com isolamento viral, todas (n = 17) foram RAT e RT-PCR positivas. Por outro lado, amostras sem isolamento viral (n = 97) foram RAT e RT-PCR positivas em 36 (37%) e 83 (86%), respectivamente. RAT e RT-PCR evidenciaram sensibilidade global e valores preditivos negativos de 100%, porém, RAT apresentou 63% de especificidade global e 32% de valor preditivo positivo (VPP), enquanto RT-PCR evidenciou menor especificidade (14%) e VPP (17%) para predizer a infectividade. Conclusão Indivíduos vacinados imunocompetentes com infecção por Ômicron ainda podem transmitir o vírus no 7° dia de sintomas, portanto, é altamente improvável que estejam transmitindo o vírus infeccioso no dia 10. Testes rápidos de antígeno podem ser usados para estimar a duração da infectividade dos casos de Ômicron. Ag. Financiadora Instituto todos pela saúde do Banco Itaú.

DETECÇÃO DE ANTICORPOS NEUTRALIZANTES CONTRA AS VARIANTES DELTA, GAMA E OMICRON APÓS IMUNIZAÇÃO POR CORONAVAC E BOOSTER COM PFIZER

Introdução A vacinação é uma ferramenta essencial para o controle da infecção por SARS-CoV-2 e da pandemia de COVID-19. O surgimento de novas variantes genéticas do vírus SARS-CoV-2 nos trouxe a questão se há diferencial capacidade neutralizante dos anticorpos quanto às variantes de preocupação (VOCs). Objetivo Nosso estudo se dirigiu a avaliar a capacidade neutralizante dos anticorpos de indivíduos imunizados com a vacina CoronaVac e dose de reforço com Pfizer contra as variantes Gama, Delta e Omicron. Método Amostras de soro foram obtidas de 41 profissionais da saúde da Faculdade de Medicina da USP, sem infecção prévia por SARS-CoV-2 no esquema vacinal CoronaVac (2 doses) seguido de dose booster com vacina Pfizer. Os níveis de anticorpos neutralizantes para as variantes Gama, Delta e Omicron foram avaliados 32 e 186 dias após a segunda dose da vacina. Também avaliamos a atividade neutralizante dos anticorpos contra a variante Omicron em 39 dos indivíduos após 62 dias de imunização de reforço, com a vacina Pfizer. Os títulos de anticorpos foram obtidos pelo Teste de Neutralização Viral (VNT) e observação de efeito citopático. Resultados A neutralização por anticorpos contra as variantes Gama, Delta e Omicron foi de 78%, 65.9% e 58.5% respectivamente, após uma média de 32 dias após a segunda dose por CoronaVac. Houve uma diminuição na frequência de anticorpos neutralizantes para 17.1%, 24.4% e 2.4% contra as variantes Gama, Delta e Omicron, respectivamente, após, em média 186 dias das duas doses da vacina CoronaVac. A dose booster com a vacina Pfizer foi capaz de induzir a produção de anticorpos neutralizantes contra a variante Omicron em 87.2% dos indivíduos avaliados. Conclusão Os indivíduos vacinados com CoronaVac apresentaram uma queda nítida de anticorpos neutralizantes contra as 3 variantes de SARS-CoV-2 analisadas após 186 dias da imunização por 2 doses. A dose de reforço com Pfizer induziu a produção de anticorpos neutralizantes contra a variante Omicron na maior parte dos indivíduos avaliados (87.2%), 60 dias após imunização. Não houve diferença significativa na frequência de anticorpos neutralizantes entre as variantes analisadas.

PREDITORES DE PROTEÇÃO CONTRA INFECÇÃO POR SARS-COV-2 APÓS DUAS DOSES DE CORONAVAC EM UMA COORTE DE PROFISSIONAIS DE SAÚDE

Introdução A elucidação dos preditores de proteção contra infecção pelo SARS-CoV-2 após a vacinação contra o mesmo pode auxiliar no controle da pandemia. Objetivo Identificar fatores de proteção contra infecção por SARS-CoV-2 após recebimento de duas doses de CoronaVac. Método Trata-se de uma coorte prospectiva de profissionais de saúde (PS) do HC-FMUSP vacinados com 2 doses da CoronaVac. O desfecho avaliado foi infecção pelo SARS-CoV-2 (confirmada por RT-PCR) desde 10 semanas após a segunda dose da vacina até pararem de trabalhar no HC-FMUSP ou até a data 08/03/2022. A infecção pelo SARS-CoV-2 foi verificada através dos registros do Centro de Atendimento ao Colaborador (CEAC) e do Núcleo de Vigilância Epidemiológica (NUVE) do HCFMUSP e através de entrevistas aos participantes do estudo. Os PS foram submetidos a sorologia para o SARS-CoV-2 para detecção de IgG anti-S (Liaison®/DiaSorin). Fatores de proteção contra infecção pelo SARS-CoV-2 foram avaliados com modelos de regressão de Cox. Os participantes assinaram um TCLE antes de ingressarem no estudo e o projeto foi aprovado no CEP do HC-FMUSP. Resultados Entre a 2ª e a 3ª dose da vacina, 3.979 PS foram avaliados. A idade mediana foi 44 anos e 79% era do sexo feminino. Casos de COVID-19 antes da 1ª dose da vacina foram detectados em 18% dos participantes. Sorologia reagente (título ≥ 33,8) foi detectada em 90% dos participantes em um teste realizado 10 semanas após a 2ª dose da vacina e houve 247 (6%) casos de COVID-19 entre a coleta desta sorologia e o recebimento da 3ª dose da vacina. Fatores de proteção contra infecção pelo SARS-CoV-2 neste período foram: diagnóstico de COVID-19 antes da 1ª dose da vacina (adjHR = 0,35), sorologia reagente coletada 10 semanas após 2ª dose da vacina (adjHR = 0,50) e idade entre 50-70 anos (adjHR = 0,52). Após a 3ª dose da vacina, 1305 PS foram avaliados. Sorologia reagente foi detectada em 99,8% dos participantes em um teste realizado 8 semanas após a 3ª dose da vacina e houve 159 (12%) casos de COVID-19 entre a coleta desta sorologia e o término do seguimento. Fatores de proteção contra infecção pelo SARS-CoV-2 no período foram: diagnóstico de COVID-19 antes da 3ª dose da vacina (adjHR = 0,57) e altos títulos da sorologia coletada 8 semanas após a terceira dose da vacina (adjHR = 0,99). Conclusão Diagnóstico prévio de COVID-19 e altos títulos de IgG contra o SARS-CoV-2 8-10 semanas após a vacinação são fatores protetores de infecção pelo SARS-CoV-2 em PS vacinados com CoronaVac. Ag. Financiadora: Instituto todos pela saúde. Nr. Processo: C1864.

Absence of neutralizing antibodies against the Omicron SARS-CoV-2 variant in convalescent sera from individuals infected with the ancestral SARS-CoV-2 virus or its Gamma variant.

OBJECTIVES: The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant. METHODS: Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant. RESULTS: Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies against the ancestral, Gamma variant, and Omicron variant, respectively. After infection with the Gamma variant, 43 (87.8%) and 2 (4.1%) sera were positive for neutralizing antibodies against the Gamma and Omicron variants, respectively. CONCLUSIONS: Neutralizing antibodies generated following mild or moderate infection with the SARS-CoV-2 ancestral strain or the Gamma variant are not protective against the Omicron variant.

Generation of neutralizing antibodies against Omicron, Gamma and Delta SARS-CoV-2 variants following CoronaVac vaccination.

Vaccination is a fundamental tool to prevent SARS-CoV-2 infection and to limit the COVID-19 pandemic. The emergence of SARS-CoV-2 variants with multiple mutations has raised serious concerns about the ability of neutralizing antibody responses elicited by prior vaccination to effectively combat these variants. The neutralizing capacity against the Gamma, Delta and Omicron variants of sera from individuals immunized with the CoronaVac vaccine remains incompletely determined. The present study evaluated 41 health care workers at the Faculdade de Medicina of the Universidade de Sao Paulo, in Sao Paulo, Brazil, naive to previous SARS- CoV-2 infection, who were vaccinated with two doses of the CoronaVac SARS-CoV-2 vaccine 28 days apart. Neutralizing antibody levels against the Gamma, Delta, and Omicron variants were measured at 32 and 186 days after the second vaccination. We also measured neutralizing antibodies against Omicron in 34 of these individuals following a subsequent booster immunization with the Pfizer vaccine. Quantification of neutralizing antibodies was performed using the Cytopathic Effect-based Virus Neutralization test. Neutralization antibody activity against the Gamma, Delta and Omicron variants was observed in 78.0%, 65.9% and 58.5% of serum samples, respectively, obtained at a mean of 32 days after the second immunization. This decreased to 17.1%, 24.4% and 2.4% of sera having activity against Delta, Gamma and Omicron, respectively, at 186 days post-vaccination. The median neutralizing antibody titers at 32 days were 1:40, 1:20 and 1:20 against Gamma, Delta and Omicron, respectively, and decreased to an undetectable median level against all variants at the later time. A booster immunization with the Pfizer vaccine elicited neutralizing antibodies against Omicron in 85% of subjects tested 60 days after vaccination. We conclude that two doses of the CoronaVac vaccine results in limited protection of short duration against the Gamma, Delta and Omicron SARS-CoV-2 variants. A booster dose with the Pfizer vaccine induced antibody neutralizing activity against Omicron in most patients which was measurable 60 days after the booster.

An international, interlaboratory ring trial confirms the feasibility of an extraction-less "direct" RT-qPCR method for reliable detection of SARS-CoV-2 RNA in clinical samples.

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is used worldwide to test and trace the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). "Extraction-less" or "direct" real time-reverse transcription polymerase chain reaction (RT-PCR) is a transparent and accessible qualitative method for SARS-CoV-2 detection from nasopharyngeal or oral pharyngeal samples with the potential to generate actionable data more quickly, at a lower cost, and with fewer experimental resources than full RT-qPCR. This study engaged 10 global testing sites, including laboratories currently experiencing testing limitations due to reagent or equipment shortages, in an international interlaboratory ring trial. Participating laboratories were provided a common protocol, common reagents, aliquots of identical pooled clinical samples, and purified nucleic acids and used their existing in-house equipment. We observed 100% concordance across laboratories in the correct identification of all positive and negative samples, with highly similar cycle threshold values. The test also performed well when applied to locally collected patient nasopharyngeal samples, provided the viral transport media did not contain charcoal or guanidine, both of which appeared to potently inhibit the RT-PCR reaction. Our results suggest that direct RT-PCR assay methods can be clearly translated across sites utilizing readily available equipment and expertise and are thus a feasible option for more efficient COVID-19 coronavirus disease testing as demanded by the continuing pandemic.

SARS-CoV-2 recombinant proteins stimulate distinct cellular and humoral immune response profiles in samples from COVID-19 convalescent patients.

OBJECTIVES: In this preliminary study we investigated cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood samples from 14 recovered coronavirus disease 2019 (COVID-19) patients and compared them to those in samples from 12 uninfected/unvaccinated volunteers. METHODS: Cellular immunity was assessed by intracellular detection of IFN-γ in CD3+ T lymphocytes after stimulation with SARS-CoV-2 spike (S1), nucleocapsid (NC), or receptor-binding domain (RBD) recombinant proteins or overlapping peptide pools covering the sequence of SARS-CoV-2 spike, membrane and nucleocapsid regions. The humoral response was examined by ELISAs and/or chemiluminescence assays for the presence of serum IgG antibodies directed to SARS-CoV-2 proteins. RESULTS: We observed differences between humoral and cellular immune profiles in response to stimulation with the same proteins. Assays of IgG antibodies directed to SARS-CoV-2 NC, RBD and S1/S2 recombinant proteins were able to differentiate convalescent from uninfected/unvaccinated groups. Cellular immune responses to SARS-CoV-2 protein stimuli did not exhibit a specific response, as T cells from both individuals with no history of contact with SARS-CoV-2 and from recovered donors were able to produce IFN-γ. CONCLUSIONS: Determination of the cellular immune response to stimulation with a pool of SARS-CoV-2 peptides but not with SARS-CoV-2 proteins is able to distinguish convalescent individuals from unexposed individuals. Regarding the humoral immune response, the screening for serum IgG antibodies directed to SARS-CoV-2 proteins has been shown to be specific for the response of recovered individuals.

Vertical transmission of SARS-CoV2 during pregnancy: A high-risk cohort.

OBJECTIVE: Identify the potential for and risk factors of SARS-CoV-2 vertical transmission. METHODS: Symptomatic pregnant women with COVID-19 diagnosis in whom PCR for SARS-CoV-2 was performed at delivery using maternal serum and at least one of the biological samples: cord blood (CB), amniotic fluid (AF), colostrum and/or oropharyngeal swab (OPS) of the neonate. The association of parameters with maternal, AF and/or CB positivity and the influence of SARS-CoV-2 positivity in AF and/or CB on neonatal outcomes were investigated. RESULTS: Overall 73.4% (80/109) were admitted in hospital due to COVID-19, 22.9% needed intensive care and there were four maternal deaths. Positive RT-PCR for SARS-CoV-2 was observed in 14.7% of maternal blood, 13.9% of AF, 6.7% of CB, 2.1% of colostrum and 3.7% of OPS samples. The interval between COVID-19 symptoms and delivery was inversely associated with SARS-CoV-2 positivity in the maternal blood (p = 0.002) and in the AF and/or CB (p = 0.049). Maternal viremia was associated with positivity for SARS-CoV-2 in AF and/or CB (p = 0.001). SARS-CoV-2 positivity in the compartments was not associated with neonatal outcomes. CONCLUSION: Vertical transmission is possible in pregnant women with COVID-19 and a shorter interval between maternal symptoms and delivery is an influencing factor.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Seroprevalence and Risk Factors Among Oligo/Asymptomatic Healthcare Workers: Estimating the Impact of Community Transmission.

We evaluated the seroprevalence of SARS-CoV-2 and risk factors among 4987 oligo/asymptomatic healthcare workers; seroprevalence was 14% and factors associated with SARS-CoV-2 infection were lower educational level (aOR, 1.93; 95% CI, 1.03-3.60), using public transport to work (aOR, 1.65; 95% CI, 1.07-2.62), and working in cleaning or security (aOR, 2.05; 95% CI, 1.04-4.03).

SARS-CoV-2 in a stream running through an underprivileged, underserved, urban settlement in São Paulo, Brazil: A 7-month follow-up.

COVID-19 pandemic has led to concerns on the circulation of SARS-CoV-2 in the environment, its infectivity from the environment and, the relevance of transmission via environmental compartments. During 31 weeks, water samples were collected from a heavily contaminated stream going through an urban, underprivileged community without sewage collection. Our results showed a statistically significant correlation between cases of COVID-19 and SARS in the community, and SARS-CoV-2 concentrations in the water. Based on the model, if the concentrations of SARS-CoV-RNA (N1 and N2 target regions) increase 10 times, there is an expected increase of 104% [95%CI: (62-157%)] and 92% [95%CI: (51-143%)], respectively, in the number of cases of COVID-19 and SARS. We believe that differences in concentration of the virus in the environment reflect the epidemiological status in the community, which may be important information for surveillance and controlling dissemination in areas with vulnerable populations and poor sanitation. None of the samples were found infectious based cultures. Our results may be applicable globally as similar communities exist worldwide.

Can preprocedural mouthrinses reduce SARS-CoV-2 load in dental aerosols?

Dental professionals work closely with patients and present an increased risk of person-to-person transmission of SARS-CoV-2. Moreover, the use of ultrasonic scalers, air-water syringes, and slow and high-speed handpieces, which are common in the dental office, generate spatter and aerosol. The use of preprocedural mouthrinses has been proposed to reduce the viral load in saliva and oropharyngeal tissues, thus decreasing viral load in dental aerosol. Although some mouthrinses demonstrates an antiviral effect, there is limited evidence about the clinical efficacy of any mouthrinse in the reduction of SARS-CoV-2 in the dental aerosol. We hypothesized that mouthrinses may reduce SARS-CoV-2 viral load in the oropharynx and its fluids reducing viral load in dental aerosol. The potential use of mouthrinses is discussed, along with proposal of in vitro and clinical studies, in order to evaluate this hypothesis. If this hypothesis holds true, dental professionals and patients may benefit from the routine use of preprocedural mouthrinses.

A Novel Saliva RT-LAMP Workflow for Rapid Identification of COVID-19 Cases and Restraining Viral Spread.

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 (reverse transcription loop-mediated isothermal amplification) workflow for viral detection in saliva, and to provide more information regarding its potential in curbing COVID-19 transmission. Clinical and contrived specimens were used to optimize formulations and sample processing protocols. Salivary viral load was determined in symptomatic patients to evaluate the clinical performance of the test and to characterize saliva based on age, gender and time from onset of symptoms. Our workflow achieved an overall sensitivity of 77.2% (n = 90), with 93.2% sensitivity, 97% specificity, and 0.895 Kappa for specimens containing >102 copies/µL (n = 77). Further analyses in saliva showed that viral load peaks in the first days of symptoms and decreases afterwards, and that viral load is ~10 times lower in females compared to males, and declines following symptom onset. NOP RT-PCR data did not yield relevant associations. This work suggests that saliva reflects the transmission dynamics better than NOP specimens, and reveals gender differences that may reflect higher transmission by males. This saliva RT-LAMP workflow can be applied to track viral spread and, to maximize detection, testing should be performed immediately after symptoms are presented, especially in females.

SARS-Cov-2 seroprevalence and risk factors among health care workers: Estimating the risk of COVID-19 dedicated units.

We evaluated the seroprevalence of SARS-CoV-2 and risk factors among 1,996 oligo/asymptomatic health care workers. The seroprevalence was 5.5% and risk factors associated with being infected with SARS-CoV-2 was professional category of cleaning (adj odds ratio 2.22, 95% confidence interval: 1.12-4.44, P: .023) and male gender (adj odds ratio: 1.54, 95% confidence interval: 1.03-2.32, P: .035).Working at dedicated COVID-19 units (high-risk group) was not an independent risk factor for seropositivity.

Decontamination and re-use of surgical masks and respirators during the COVID-19 pandemic.

OBJECTIVES: The coronavirus disease 2019 pandemic increased global demand for personal protective equipment (PPE) and resulted in shortages. The study evaluated the re-use of surgical masks and respirators by analysing their performance and safety before and after reprocessing using the following methods: oven, thermal drying, autoclave, and hydrogen peroxide plasma vapour. METHODS: In total, 45 surgical masks and 69 respirators were decontaminated. Visual integrity, air permeability, burst resistance, pressure differential and particulate filtration efficiency of new and decontaminated surgical masks and respirators were evaluated. In addition, 14 used respirators were analysed after work shifts before and after decontamination using reverse transcription polymerase chain reaction (RT-PCR) and viral culturing. Finally, reprocessed respirators were evaluated by users in terms of functionality and comfort. RESULTS: Oven decontamination (75 °C for 45 min) was found to be the simplest decontamination method. Physical and filtration assays indicated that all reprocessing methods were safe after one cycle. Oven decontamination maintained the characteristics of surgical masks and respirators for at least five reprocessing cycles. Viral RNA was detected by RT-PCR in two of the 14 used respirators. Four respirators submitted to viral culture were PCR-negative and culture-negative. Reprocessed respirators used in work shifts were evaluated positively by users, even after three decontamination cycles. CONCLUSION: Oven decontamination is a safe method for reprocessing surgical masks and respirators for at least five cycles, and is feasible in the hospital setting.

Nucleoprotein-based ELISA for detection of SARS-COV-2 IgG antibodies: Could an old assay be suitable for serodiagnosis of the new coronavirus?

OBJECTIVES: We evaluated the performance of a nucleoprotein-based enzyme-linked immunosorbent assay (ELISA) for detection of IgG antibodies to SARS-CoV-2. METHODS: The ELISA was based on serum IgG reactivity to a 46-kDa protein derived from the recombinant SARS-CoV2 nucleoprotein. Assay sensitivity was assessed using serum samples from 134 COVID-19 confirmed cases obtained > 15 days after symptom onset. Specificity was determined by testing sera from 94 healthy controls. Cross-reactivity was evaluated with sera from 96 individuals with previous dengue or zika virus-confirmed infections, with 44 sera from individuals with confirmed infections to other respiratory viruses or with bacterial and fungal infections that cause pneumonia and with 40 sera negative for SARS-CoV-2 nucleoprotein by commercial ELISA kits. RESULTS: The majority of subjects were male and ≥ 60 years old. Assay sensitivity was 90.3 % (95 % confidence interval 84.1 %-94.2 %) and specificity was 97.9 % (92.6 %-99.4 %). There was no cross-reactivity with sera from individuals diagnosed with dengue, zika virus, influenza virus, rhinovirus, adenovirus, respiratory syncytial virus, seasonal coronavirus, Mycobacterium tuberculosis, Staphylococcus (S. aureus and coagulase-negative), Streptococcus pneumoniae, Klebsiella pneumoniae and the fungus Aspergillus fumigatus. The level of concordance of our test with results from commercial ELISA kits was 100 %. CONCLUSION: The nucleoprotein-based ELISA was specific for detection of IgG anti-nucleoprotein antibodies to SARS-CoV-2. It utilizes a frequently employed low expense assay protocol and is easier to perform than other currently available commercial SARS-CoV2 antibody detection tests.