Seroepidemiologicalmonitoring of SARS-CoV-2 IgG in main railway stations in the city of Buenos Aires, Argentina / Monitoreo seroepidemiológico de igg contra el sars-cov-2 en estaciones ferroviarias cabeceras de la ciudad autónoma de buenos aires, argentina

RESUMEN INTRODUCCIÓN : Los estudios de seroprevalencia permiten monitorear la circulación del SARS-CoV-2 y dan información para evaluar medidas sanitarias. El objetivo fue conocer la proporción y evolución de la seropositividad en puntos de gran circulación de la Ciudad Autónoma de Buenos Aires (CABA) y las características clínico-epidemiológicas de los seropositivos, de abril a octubre de 2020. MÉTODOS : Se realizó un estudio descriptivo transversal de seis rondas de testeos rápidos serológicos y una encuesta de datos epidemiológicos. Se realizó un muestreo por conveniencia en tres estaciones ferroviarias cabeceras de CABA consideradas puntos de alto tránsito bidireccional del Área Metropolitana de Buenos Aires. RESULTADOS : Participaron 7339 personas. La proporción de seropositivos fue 0,6% (IC95%: 0,2-0,9) en la primera ronda y aumentó a 5,6% en la última (IC95%: 4,3-7). Al inicio aumentó la seropositividad en residentes de CABA y de la zona sur de la Región Metropolitana de Buenos Aires. El antecedente de haber presentado síntomas y el de contacto con personas con COVID-19 fueron las únicas variables relacionadas con el resultado de inmunoglobulina G positivo (p <0,05). El 56,1% (n = 97) de los seropositivos no tuvo síntomas. El 78,4% (n = 134) no fue diagnosticado en la etapa aguda. DISCUSIÓN : La seropositividad fue en ascenso en cada ronda, en coincidencia con la situación epidemiológica de la zona de residencia. Las características epidemiológicas como la proporción de seropositivos sin antecedentes de síntomas, reafirman la importancia de las medidas sanitarias poblacionales.

ABSTRACT INTRODUCTION : Seroprevalence studies allow monitoring the circulation of SARS-CoV-2, providing information to evalúate public health measures. The aim of this study was to determine the proportion and evolution of seropositivity in high circulation points in the Ciudad Autónoma de Buenos Aires (CABA) and clinical and epidemiological characteristics of seropositive individuals from April to October 2020. METHODS : A descriptive cross-sectional study was conducted during six rounds, using rapid serological testing together with an epidemiological data survey. A convenience sample was selected in three CABA railway stations considered as high bi-directional traffic points in the Buenos Aires Metropolitan Area (AMBA). RESULTS : 7,339 people participated. The seropositive proportion was 0.6% (95%CI: 0.2-0.9) in the first round, and rose to 5.6% in the last one (95%CI: 4.3-7). Initially, seropositivity increased in CABA residents and those living in the southern part of the Buenos Aires Metropolitan Region. Having presented symptoms and history of contact with COVID-19 cases were the only variables found to be related to positive IgG results (p<0.05). Among seropositive participantes, 56.1% (n=97) had no symptoms and 78.4% (n=134) didn't receive a COVID-19 diagnosis in the acute stage. DISCUSSION : Seropositivity increased between rounds, according to the epidemiological situation in the area of residence. Epidemiological characteristics, such as the proportion of seropositive individuals with no history of symptoms, reaffirm the importance of public health and social measures.

Application of combined detection of enterovirus nucleic acid and antibody in early etiological diagnosis for hand-foot-and-mouth disease / 中华检验医学杂志

Objective To assess the value of combined detection of enterovirus nucleic acid and antibody in early etiological diagnosis for hand-foot-and-mouth disease ( HFMD).Methods A case-control study was conducted.A total of 1 066 cases of children clinically diagnosed with HFMD from Hangzhou Children′s Hospital were involved into the research group from January to June 2014, consisting of 401 common cases and 665 severe cases; Throat swabs and serum samples from these children underwent combined detection for EV71/CA16/EV of enterovirus nucleic acid by fluorescence quantitative RT-PCR and for EV71/CA16-IgM by ELISA.All data were analyzed with SPSS 16.0.Results The total positive rate of enterovirus nucleic acid EV71/CA16/EV by fluorescence quantitative RT-PCR in the 1 066 cases of children clinically diagnosed with HFMD was 75.52%( 805/1 066 ) ( 95%CI: 72.80%-78.05%).But the total positive rate of combined detection was 91.46%( 975/1 066 ) ( 95%CI:89%.58-93.04%).The total positive rate of combined detection is higher than that of RT-PCR test(χ2 =98.338,P=0.000).The positive rate of EV71 type of combined detection was 64.63%(689/1 066)(95%CI:61.67%-67.49%),which is 15.38%higher than that of RT-PCR test 49.25%(525/1 066)(95%CI:46.21%-52.29%)(χ2 =51.453, P=0.000).In 665 severe cases of HFMD, the total positive rate of combined detection was 96.69%(643/665)(95%CI:94.95%-97.87%), which is higher than that of RT-PCR test 79.25%(527/665)(95%CI:75.92%-82.22%)(χ2 =95.607, P =0.000).In the severe cases, the positive rate of EV71 type of combined detection was 87.52%( 582/665 ) ( 95%CI:84.71%-89.89%) , which is 18.95% higher than that of RT-PCR test 68.57%(456/665) (95%CI:64.87%-72.06%) (χ2 =69.665, P=0.000).In the fatal cases, the positive rate of EV71 type of combined detection was 95.92%(94/98) (95%CI:89.28%-98.68%).Conclusions The combined detection of enterovirus nucleic acid and specific IgM antibody can significantly increase the positive rate of HFMD, especially for severe cases.The combine detection increases both the total positive rate and EV71 positive rate.Thus it has a high potential for becoming a new guidelines for laboratory diagnosis of HFMD.

The value of detection of three anti-Epstein-Barr viral antibodies for nasopharyngeal carcinoma diagnosis / 中华检验医学杂志

Objective To evaluate the value of Epstein-Barr virus (EBV) IgG antibody to EBV Rta protein(Rta-IgG),IgA antibody to EBV early antigen (EA-IgA) and IgA antibody to EBV viral capsid antigen(VCA-IgA) for nasopharyngeal carcinoma (NPC) diagnosis.Methods From May 2012 to July 2013,serum samples from 8 884 healthy donors,1 546 clinical screening patients and 155 NPC patients in Fujian Medical University Union Hospital were collected,and EBV Rta-IgG,EA-IgA and VCA-IgA were detected by ELISA.The ROC curve analysis and correlation analysis were performed to assess the value of Rta-IgG,EA-IgA and VCA-IgA for NPC diagnosis.The positive rate among three kinds of antibodies were compared with chi-square test.Results Positive rates of EBV Rta-IgG,VCA-IgA and EA-IgA in NPC patient group were 81.9％ (127/155),90.3％ (140/155) and 48.3％ (75/155),respectively,which were higher than those in clinical screening patient group and healthy donor group (x2 =1 538.6,479.3 and 643.3 respectively,P ＜ 0.01).The sensitivity of VCA-IgA (90.3％,140/155) and the specificity of EA-IgA (95.1％,9 915/10 430) were the highest in all groups.Further analysis showed that negative predictive value of EBV Rta-IgG,VCA-IgA and EA-IgA for NPC diagnosis were 99.7％ (9 826/9 854),99.8％ (8 168/8 183),99.2％ (9 915/9 995),respectively,suggesting that three anti-EBV antibodies showed very good negative predictive value for NPC diagnosis.Next,combined detection of three anti-EBV antibodies could improve the sensitivity (94.1％,146/155) and specificity (98.9％,10 469/10 585) for the NPC diagnosis.Conclusion The EBV Rta-IgG,VCA-IgA and EA-IgA all show the clinical value for NPC diagnosis,and combined detection for Rta-IgG,VCA-IgA and EA-IgA is more suitable to screen NPC and can improve the sensitivity and specificity of NPC diagnosis.

Serological study of blood donors with occult hepatitis B virus infection / 中国医师杂志

Objective Some blood donors were negative for the surface antigen but positive for the core antibody,leading to acute hepatitis.This study was to determine the seroprevalence of the hepatitis B core antibody in voluntary blood donors.Methods A total of 9100 donor samples were screened for hepatitis B surface antigen and Hepatitis B core antibody with enzyme-linked immunosorbent assay(ELISA).The samples which were positive for the core antibody were subjected to real-time polymerase chain reaction (PCR) for the hepatitis B DNA detection.Results Among the 9100 donors,911 (10.01％) donors were positive for the core antibody.The hepatitis B surface antigen was positive in 199 (2.19％) donors.Among the 911 donors who were positive for the core antibody,820 (90.01％) donors were negative for the HB-sAg,and 35 donors were positive for hepatitis B DNA.Conclusions If a routine screening of the sera for the core antibody is not done,the HBV DNA viraemia may not be identified.The absence of the surface antigen in the blood of apparently healthy individuals may not be sufficient to ensure the lack of the circulating virus.It is necessary to attach importance to the blood donors screening HBsAg-negative population further serological testing,suspicious specimens should detect HBV DNA.

Serum levels of antibody against enterovirus 71 in healthy children at Shanghai in 2011 / 中华传染病杂志

Objective To test the levels of enterovirus 71 (EV71) antibody among children of different ages in Shanghai in 2011,and to investigate the relationship between antibody levels and virus infection.Methods EV71 antibody was detected by microneutralization assay from the serum specimens of healthy children of different ages collected during July to August,2011.The results were analyzed by t test for quantitative data with normal distribution,and by x2 test for count data.Results The positive rate of EV71 antibody among the 93 serum specimens was 58.1％ (54/93).The geometric mean titer (GMT) of EV71-specific neutralizing antibody was 1 ∶ 14.48.The positive rate of EV71 antibody in infants less than 6 months old was 87.5％ (21/24),and the GMT was 1∶29.56.In children aged 2 to 3 years,the positive rate of EV71 antibody decreased to 3.7％ (1/27),and GMT decreased to 1∶4.21,which were both statistically significantly lower than those less than 6 months old (x2 =36.37,t=7.58; both P＜0.01).The positive rate of EV71 antibody increased to 83.3％ (20/24) in children aged 5 to 6 years,with GMT reaching 1∶21.74.Whereas in children aged 7 to 8 years,the positive rate was 66.7％ (12/18) and GMT was 1∶20.76,without statistically significant difference compared with those aged 5 to 6 years (x2 =1.58,t=0.597; both P＞0.05).No statistically significant difference was found between boys and girls in positive rate of EV71 antibody [62.7 ％ (32/51) vs 52.4 ％ (22/42),x2 =1.02,P＞0.05] or GMT (1 ∶ 16.23 vs 1 ∶ 12.61,t=0.881,P＞0.05).Conclusions Children aged 2 to 3 years were at higher risk for EV71 infection,with EV71 antibody level significantly lower than other age groups.

Soroprevalência de anticorpos contra vírus herpes simples 1-2 no Brasil / Seroprevalencia de anticuerpos contra virus herpes simples 1-2 en Brasil / Seroprevalence of herpes simplex 1-2 antibodies in Brazil

OBJETIVO: Estimar a soroprevalência de anticorpos por vírus herpes simples (HSV-1 e HSV-2) e analisar fatores associados no Brasil. MÉTODOS: Estudo transversal realizado entre 1996 e 1997 em 1.090 indivíduos com idade entre um e 40 anos da população geral, em quatro diferentes regiões geográficas no Brasil. Foram analisadas amostras sangüíneas para detecção de anticorpos para HSV-1 e HSV-2 com teste tipo-específico Elisa. Foram descritas freqüências e proporções, comparadas entre grupos utilizando o teste de Fisher bilateral exato. Foi realizada análise de regressão logística para avaliar influência das variáveis sociodemográficas e histórico de DST, sobre a soroprevalência de HSV-1 e/ou HSV-2. RESULTADOS: As soroprevalências de anticorpos para HSV-1 e HSV-2, ajustadas por idade, foram 67,2 por cento e 11,3 por cento respectivamente, sem diferença quanto ao sexo e maiores na Região Norte...

OBJECTIVE: To estimate the seroprevalence of HSV-1 and HSV-2 antibodies in Brazil and to analyze factors associated. METHODS: Cross-sectional study including subjects aged 1-40 years from the general population in four different geographical areas in Brazil between 1996 and 1997. All subjects were stratified by age and gender and 1,090 of them were included in the final analysis. Blood samples were tested for HSV-1 and HSV-2 antibodies by type-specific (gG1 and gG2) ELISA. Frequencies and proportions were described and compared among groups using two-sided Fisher's exact test. A logistic regression analysis was performed to assess the influence of the variables age, gender, geographical area, socioeconomic condition, past history of STD, seropositivity for anti-HSV-1 or anti-HSV-2 and interactions of any of these factors on the seroprevalence of HSV-1 and/or HSV-2. RESULTS: The age-adjusted seroprevalences of HSV-1 and HSV-2 antibodies were 67.2 percent and 11.3 percent, respectively, without sex differences and being higher in the North region...

OBJETIVO: Estimar la seroprevalencia de anticuerpos por virus herpes simples (HSV-1 y HSV-2) en diferentes áreas geográficas en Brasil y analizar factores asociados. MÉTODOS: Estudio transversal realizado entre 1996 y 1997 con individuos de la población en general en cuatro diferentes áreas geográficas en Brasil y estratificados por edad (de uno a 40 años) y sexo, de los cuales 1.090 fueron incluidos en el análisis final. Fueron analizadas muestras de sangre para detección de anticuerpos para HSV-1 y HSV-2 con prueba tipo-específica ELISA gG1-gG2. Fueron descritas frecuencias y proporciones y comparadas entre grupos utilizando la prueba de Fisher bilateral exacta. Fue realizado análisis de regresión logística para evaluar influencia de las variables edad, sexo, geografía, grupo económico, histórico de DST, seropositividad para anti-HSV-1 o anti-HSV-2 e interacciones de cualquiera de esos factores sobre la seroprevalencia de HSV-1 y/o HSV-2. RESULTADOS: La tasa de seroprevalencia de anticuerpos para HSV-1 ajustada por edad fue de 67,2 por ciento, sin diferencia con relación al sexo, siendo mayor en la Región Norte...

Analysis of levels of antibodies against influenza A virus of population in Shanghai during 2009 / 中华传染病杂志

Objective To know the levels of antibodies against influenza A virus subtypes H1 and H3 of population in Shanghai during 2009, and the detection of antibodies against avian influenza virus subtypes H5 and H9 in population which contacts with avian. Methods The serological survey of the antibodies against influenza A viruses subtypes H1, H3, H5 and H9 in 356 close contacts with avian (professional population) and 332 general subjects (general population) at various age groups were carried out using hemagglutinin inhibit (HI) test. Results The positive rates of antibodies against influenza virus A/Brisbane/59/2007 (H1N1) in general population and professional population were 82.8% (275/332) and 73.9% (263/356), respectively; those of A/Brisbane/10/2007 (H3N2)were 50.6% (168/332) and 54.8% (195/356), respectively. The positive rate of antibodies against influenza virus A/Brisbane/59/2007 (H1N1 )was significantly higher than that of influenza A viruses subtype H3, which was consistent with etiological survey of influenza virus in Shanghai during 2008.The positive rates of antibodies against influenza A virus subtype H5 in professional population and general population were 4.2% (15/356) and 0.3% (1/332), respectively; those of influenza A virus subtype H9 were 34.6% (123/356) and 2.4% (8/332), respectively. The positive rates of antibodies against influenza virus A/Brisbane/59/2007 (H1N1 ) and A/Brisbane/10/2007 (H3N2) in age groups of 6 months-5 years and ≥60 years were lower than other age groups. Conclusions The immune protective response against seasonal influenza A subtype H1 and H3 of population in Shanghai is high,while those of children and the elders were low. The levels of antibodies against influenza A viruses subtype H5 and H9 in professinal population present obviously ascending trend, which indicates that the etiological and serological survey of influenza virus in this population should be enhanced.

Prevalence of antibodies against measles, mumps, and rubella before and after vaccination of school-age children with three different triple combined viral vaccines, Rio Grande do Sul, Brazil, 1996 / Prevalencia de anticuerpos contra sarampión, paperas y rubéola en niños en edad escolar antes y después de la vacunación con tres vacunas triples antivirales combinadas diferentes, Rio Grande do Sul, Brasil, 1996

OBJECTIVE: We evaluated the seroprevalence for measles, mumps, and rubella in school-age children (6-12 years old) before and after the administration of three triple combined viral vaccines. METHODS: In two municipal schools of Rio Grande do Sul, Brazil, 692 blood samples were collected before vaccination and 636 samples 21 to 30 days after vaccination during 1996. IgG antibody seropositivity was investigated by enzyme-linked immunosorbent assay (measles and mumps with Enzygnost [Behring, Marburg, Germany]; rubella with Rubenostika [Organon Teknica, Boxtel, the Netherlands]). The vaccines compared were: A: E-Zagreb, L-Zagreb, and Wistar RA 27/3 (Tresivac); B: Moraten, J-Lynn, and Wistar RA 27/3 (M-M-R II); and C: Schwarz, Urabe AM-9, and Wistar RA 27/3 (Trimovax). RESULTS: Before vaccination, 79.2 percent [95 percent confidence interval (CI) = 76.0 percent-82.2 percent] of the samples were positive for measles, 69.4 percent (95 percent CI = 65.8 percent-72.8 percent) for mumps, and 55.4 percent (95 percent CI = 51.6 percent-59.2 percent) for rubella. After vaccination with the A, B, and C vaccines, seropositivity was 100.0 percent, 99.5 percent, and 100.0 percent, respectively for measles; 99.5 percent, 94.5 percent, and 92.0 percent for mumps; and 92.6 percent, 91.3 percent, and 88.6 percent for rubella. CONCLUSIONS: About one-fifth (20.8 percent) of the schoolchildren who could have been vaccinated against measles at age 9 months had levels of antibodies insufficient for protection. In the sample of schoolchildren without previous vaccination against mumps and rubella, high proportions of susceptible levels were found. All vaccines were immunogenic, but vaccine A yielded a seroconversion rate of 99.5 percent for the mumps component, which was significantly higher than the other two vaccines (P < 0.01).

OBJETIVO: Se evaluó la seroprevalencia para sarampión, paperas y rubéola en niños en edad escolar (6-12 años) antes y después de la administración de tres vacunas triples antivirales combinadas. MÉTODOS: Se colectaron 692 muestras de sangre antes de la vacunación y 636 muestras entre 21 y 30 días después de la vacunación a niños de dos escuelas municipales de Rio Grande do Sul, Brasil, durante 1996. Se investigó la seropositividad de anticuerpos de la clase IgG mediante un ensayo de inmunoadsorción enzimática tipo ELISA (sarampión y paperas con Enzygnost [Behring, Marburgo, Alemania] y rubéola con Rubenostika [Organon Teknica, Boxtel, Países Bajos]). Las vacunas comparadas fueron: a) E-Zagreb, L-Zagreb y Wistar RA 27/3 (Tresivac); b) Moraten, J-Lynn y Wistar RA 27/3 (M-M-R II); y c) Schwarz, Urabe AM-9 y Wistar RA 27/3 (Trimovax). RESULTADOS: Antes de la vacunación, 79,2 por ciento (intervalo de confianza [IC] 95 por ciento: 76,0 a 82,2) de las muestras fueron positivas para sarampión, 69,4 por ciento (IC 95 por ciento: 65,8 a 72,8) para paperas y 55,4 por ciento (IC 95 por ciento: 51,6 a 59,2) para rubéola. Después de la vacunación con las vacunas A, B y C, la seropositividad fue de 100 por ciento, 99,5 por ciento y 100 por ciento, respectivamente para sarampión; de 99,5 por ciento, 94,5 por ciento y 92,0 por ciento para paperas; y de 92,6 por ciento, 92,3 por ciento y 88,6 por ciento para rubéola. CONCLUSIONES: Alrededor de un quinto (20,8 por ciento) de los escolares que pudieron haber sido vacunados contra el sarampión a los 9 meses de edad tenían niveles de anticuerpos insuficientes para protegerlos. En la muestra de escolares sin vacunación previa contra paperas y rubéola se encontró una alta proporción de niños susceptibles. Todas las vacunas fueron inmunogénicas, pero la vacuna A produjo una tasa de seroconversión de 99,5 por ciento para el componente de paperas, significativamente mayor que la de las otras dos vacunas (P < 0,01).

Relationship between CagA seropositivity of Helicobacter pylori and Gastrointestinal malignant tumor / 中国医师杂志

0.1) were not significantly different.Conclusion The seropositivity of H.pylori,anti-CagA and anti-H.pylori-IgG are associated with the risk of gastric cancer.

Preparation and characterization of polyclonal antibody against N protein of SARS-CoV / 解放军医学杂志

Objective To prepare and characterize the polyclonal antibody against N protein of SARS-CoV. Methods The polyclonal antibody against SARS-CoV N was obtained from immunized rabbit with purified GST-N. The titer of the antibody was determined by indirect ELISA, and the specificity by Western blot and immunochemical staining. Results The rabbit′s antibody against SARS-CoV N was prepared successfully. The titer of antiserum against SARS-CoV N was about 1.2?10~ -5 . Western blot and immunochemical staining analysis showed that the polyclonal antibody could bind to the expressed fusion protein specifically. Conclusion The rabbit′s antibody against SARS-CoV N has been prepared successfully, and it can be a useful reagent for clinical diagnosis and further research.

Little role of anti-gB antibodies in neutralizing activity of patient's sera with human cytomegalovirus (HCMV) infection

Human cytomegalovirus (HCMV) gB is known to play important roles in cell surface attachment, virion penetration, spread of infection from cell to cell, and provocation of neutralizing antibody. This study was performed to determine the role of anti-HCMV gB antibody in overall neutralizing response in patients with HCMV infection and healthy control with past infection. HCMV gB was stably expressed in 293 cells. With the stable cell line expressing gB as a specific immunosorbent, anti-gB antibody was removed from the current and past HCMV-infected sera and the remaining neutralizing activity was measured by plaque assay. It was shown that 19-50% of the total virus-neutralizing activity of sera with past HCMV infections was derived from anti-gB antibody, but anti-gB antibody had little effect on the total serum virus-neutralizing activity in patients currently infected with HCMV. This result suggests that neutralizing antibody to HCMV gB may reflect disease status.

Study on severe acute respiratory syndrome seroepidemiology after its outbreak in a general hospital / 中华传染病杂志

Objectives To study the level and development of serum specific antibody against severe acute respiratory syndrome coronavirus(SARS-CoV)of different populations in SARS pestilence district after SARS outbreak in a general hospital.Discuss SARS sub-clinical infection and protective action of the IgG antibody.Methods Seroepidemiology method,enzyme-linked immunosorbent assay (ELISA)and indirect immunfluorescence assay(IFA)were employed to investigate the changing level of serum antibody to SARS-associated coronavirus in non-SARS population in SARS pestilence district during and after SARS outbreak.The development of IgM and IgG antibody in patients with SARS in 6 weeks after the onset of SARS was studied qualitatively.The level changing of IgG antibody in con- valescent patients with SARS in 82 weeks after the onset was observed dynamically.Results The ELISA test outcome of IgG antibody was negative in 200 non-SARS people who were random samples of normal mass in SARS pestilence district and common community.The positive rate was 0.41% in 487 SARS high risk population tested by ELISA,but showed negative when retested by IFA.The A value level of IgG antibody existed significant difference in non SARS mass during and after SARS outbreak and the later's was higher them the former's(P

Analysis of viral etiology of sporadic viral meningitis / 中华传染病杂志

0.05).) Conclusions Coxsackie virus is the most common pathogen in patients with viral meningitis in Chaoshan district, and the organization of disease prevention and scientific research and clinical medical should attach importance to it.

Study on the significance of S/Co ratio of a domestic reagent used for anti-hepatitis C virus antibody detection / 中华传染病杂志

Objective To study the significance of the sample S/Co ratio when using a domestic reagent for anti-hepatitis C virus(HCV)antibody detection and to explore the procedure and standard of anti-HCV antibody diagnosis by using this domestic reagent.Methods Anti-HCV antibody was detected in 295 000 blood donors by a domestic anti-HCV reagent with enzyme-linked immunosorbent assay(ELISA)method and the reactive samples were tested again by ortho anti-HCV antibody reagent.The samples which anti-HCV antibodies were determined as positive by ortho anti-HCV rea- gent were examined by recombinant immunoblot assay(RIBA)reagent and 106 samples of them were also tested for HCV RNA.Results Six hundred and eighty-one samples were reactive in 295 000 samples screened by the domestic ELISA reagent,the reactive ratio was 0.23 %.Among the reactive samples screened by the domestic ELISA reagent,367 samples were determined as positive by ortho anti-HCV reagent while 66.2% of them showed a S/Co ratio≥3.8.The consistency rate between positive results determined by the domestic reagent and RIBA reagent respectively was 53.8%.For the samples showing S/Co ratio≥3.8 by ortho anti-HCV reagent,94.2% had a S/Co ratio≥8.0 when using the domestic ELISA reagent,while the percentage of samples showing S/Co ratio