西班牙国家流行病学中心Marina Pollán对西班牙SARS-CoV-2的流行率进行了一项全国性的、基于人群的血清学检测。该成果于2020年7月6日发表在《柳叶刀》杂志上。

西班牙是受COVID-19大流行影响最大的欧洲国家之一。鉴于无症状病例的存在，且很少获得诊断检查的机会，血清学调查是评估流行程度的一种有价值的工具。这项基于人口的全国性研究旨在评估西班牙在国家和地区级别的SARS-CoV-2感染的血清阳性率。

通过按省市规模分层，研究组从市政登记册中选择了35883户家庭，并邀请所有居民参加。2020年4月27日至5月11日，共招募了61075名参与者，回答了一份关于COVID-19症状史和危险因素的问卷调查，接受了护理点的抗体检测，根据患者意愿收集血液样本进行免疫分析。

即时诊断的血清阳性率为5.0%，免疫检测结果为4.6%，特异性-敏感性范围为3.7%-6.2%，性别之间无显著差异，年龄在10岁以下的儿童血清阳性率较低（即时检验<3.1%）。地域差异很大，马德里附近患病率较高（>10%），沿海地区患病率较低（<3%）。195名PCR阳性者在研究访视前14天以上的血清患病率为87.6%（两项检测均为阳性）至91.8%（任一项检测为阳性）。在7273名患有嗅觉异常或至少有三种症状的人群中，血清阳性率从15.3%到19.3%不等。约有三分之一的血清反应阳性患者无症状，范围从21.9%到35.8%。只有19.5%的有症状参与者在护理点检测和免疫分析中均呈阳性反应。

总之，即使在热点地区，大多数西班牙人口也对SARS-CoV-2感染有血清反应。大多数经PCR确诊的病例都可检测到抗体，但相当一部分有COVID-19症状的人没有进行PCR检测，且至少三分之一的感染是无症状的。研究结果强调需要保持公共卫生措施以避免新疫情流行。

附：英文原文

Title: Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study

Author: Marina Pollán, Beatriz Pérez-Gómez, Roberto Pastor-Barriuso, Jesús Oteo, Miguel A Hernán, Mayte Pérez-Olmeda, Jose L Sanmartín, Aurora Fernández-García, Israel Cruz, Nerea Fernández de Larrea, Marta Molina, Francisco Rodríguez-Cabrera, Mariano Martín, Paloma Merino-Amador, Jose León Paniagua, Juan F Muoz-Montalvo, Faustino Blanco, Raquel Yotti, Faustino Blanco, Rodrigo Gutiérrez Fernández, Mariano Martín, Saturnino Mezcua Navarro, Marta Molina, Juan F. Muoz-Montalvo, Matías Salinero Hernández, Jose L. Sanmartín, Manuel Cuenca-Estrella, Raquel Yotti, José León Paniagua, Nerea Fernández de Larrea, Pablo Fernández-Navarro, Roberto Pastor-Barriuso, Beatriz Pérez-Gómez, Marina Pollán, Ana Avellón, Giovanni Fedele, Aurora Fernández-García, Jesús Oteo Iglesias, María Teresa Pérez Olmeda, Israel Cruz, Maria Elena Fernandez Martinez, Francisco D. Rodríguez-Cabrera, Miguel A. Hernán, Susana Padrones Fernández, José Manuel Rumbao Aguirre, José M. Navarro Marí, Begoa Palop Borrás, Ana Belén Pérez Jiménez, Manuel Rodríguez-Iglesias, Ana María Calvo Gascón, María Luz Lou Alcaine, Ignacio Donate Suárez, Oscar Suárez álvarez, Mercedes Rodríguez Pérez, Margarita Cases Sanchís, Carlos Javier Villafáfila Gomila, Lluis Carbo Saladrigas, Adoración Hurtado Fernández, Antonio Oliver, Elías Castro Feliciano, María Noemí González Quintana, José María Barrasa Fernández, María Araceli Hernández Betancor, Melisa Hernández Febles, Leopoldo Martín Martín, Luis-Mariano López López, Teresa Ugarte Miota, Inés De Benito Población, María Sagrario Celada Pérez, María Natalia Vallés Fernández, Tomás Maté Enríquez, Miguel Villa Arranz, Marta Domínguez-Gil González, Isabel Fernández-Natal, Gregoria Megías Lobón, Juan Luis Muoz Bellido, Pilar Ciruela, Ariadna Mas i Casals, Maria Doladé Botías, M. Angeles Marcos Maeso, Dúnia Pérez del Campo, Antonio Félix de Castro, Ramón Limón Ramírez, Maria Francisca Elías Retamosa, Manuela Rubio González, María Sinda Blanco Lobeiras, Alberto Fuentes Losada, Antonio Aguilera, German Bou, Yolanda Caro, Noemí Marauri, Luis Miguel Soria Blanco, Isabel del Cura González, Montserrat Hernández Pascual, Roberto Alonso Fernández, Paloma Merino-Amador, Natalia Cabrera Castro, Aurora Tomás Lizcano, Cristóbal Ramírez Almagro, Manuel Segovia Hernández, Nieves Ascunce Elizaga, María Ederra Sanz, Carmen Ezpeleta Baquedano, Ana Bustinduy Bascaran, Susana Iglesias Tamayo, Luis Elorduy Otazua, Rebeca Benarroch Benarroch, Jesús Lopera Flores, Antonia Vázquez de la Villa

Issue&Volume: 2020-07-06

Abstract: Background

Spain is one of the European countries most affected by the COVID-19 pandemic. Serological surveys are a valuable tool to assess the extent of the epidemic, given the existence of asymptomatic cases and little access to diagnostic tests. This nationwide population-based study aims to estimate the seroprevalence of SARS-CoV-2 infection in Spain at national and regional level.

Methods

35883 households were selected from municipal rolls using two-stage random sampling stratified by province and municipality size, with all residents invited to participate. From April 27 to May 11, 2020, 61075 participants (75·1% of all contacted individuals within selected households) answered a questionnaire on history of symptoms compatible with COVID-19 and risk factors, received a point-of-care antibody test, and, if agreed, donated a blood sample for additional testing with a chemiluminescent microparticle immunoassay. Prevalences of IgG antibodies were adjusted using sampling weights and post-stratification to allow for differences in non-response rates based on age group, sex, and census-tract income. Using results for both tests, we calculated a seroprevalence range maximising either specificity (positive for both tests) or sensitivity (positive for either test).

Findings

Seroprevalence was 5·0% (95% CI 4·7–5·4) by the point-of-care test and 4·6% (4·3–5·0) by immunoassay, with a specificity–sensitivity range of 3·7% (3·3–4·0; both tests positive) to 6·2% (5·8–6·6; either test positive), with no differences by sex and lower seroprevalence in children younger than 10 years (10%) and lower in coastal areas (<3%). Seroprevalence among 195 participants with positive PCR more than 14 days before the study visit ranged from 87·6% (81·1–92·1; both tests positive) to 91·8% (86·3–95·3; either test positive). In 7273 individuals with anosmia or at least three symptoms, seroprevalence ranged from 15·3% (13·8–16·8) to 19·3% (17·7–21·0). Around a third of seropositive participants were asymptomatic, ranging from 21·9% (19·1–24·9) to 35·8% (33·1–38·5). Only 19·5% (16·3–23·2) of symptomatic participants who were seropositive by both the point-of-care test and immunoassay reported a previous PCR test.

Interpretation

The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas. Most PCR-confirmed cases have detectable antibodies, but a substantial proportion of people with symptoms compatible with COVID-19 did not have a PCR test and at least a third of infections determined by serology were asymptomatic. These results emphasise the need for maintaining public health measures to avoid a new epidemic wave.

DOI: 10.1016/S0140-6736(20)31483-5

Source: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31483-5/fulltext