Seroprevalence of SARS-CoV-2 antibody among urban Iranian population: findings from the second large population-based cross-sectional study

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Abstract

Background

The first large serosurvey in Iran found a SARS-CoV-2 antibody seroprevalence of 17.1% among the general population in the first wave of the epidemic by April, 2020. The purpose of the current study was to assess the seroprevalence of COVID-19 infection among Iranian general population after the third wave of the disease.

Methods

This population-based cross-sectional study was conducted on 7411 individuals aged ≥10 years old in 16 cities across 15 provinces in Iran between January and March, 2021. We randomly sampled individuals registered in the Iranian electronic health record system based on their national identification numbers and invited them by telephone to a healthcare center for data collection. Presence of SARS-CoV-2-specific IgG and IgM antibodies was assessed using the SARS-CoV-2 ELISA kits. The participants were also asked about their recent COVID-19-related symptoms, including cough, fever, chills, sore throat, headache, dyspnea, diarrhea, anosmia, conjunctivitis, weakness, myalgia, arthralgia, altered level of consciousness, and chest pain. The seroprevalence was estimated after adjustment for population weighting and test performance.

Results

The overall population-weighted seroprevalence adjusted for test performance was 34.2% (95% CI 31.0-37.3), with an estimated 7,667,874 (95% CI 6,950,412-8,362,915) infected individuals from the 16 cities. The seroprevalence varied between the cities, from the highest estimate in Tabriz (39.2% [95% CI 33.0-45.5]) to the lowest estimate in Kerman (16.0% [95% CI 10.7-21.4]). In the 16 cities studied, 50.9% of the seropositive individuals did not report a history of symptoms suggestive of COVID-19, implying an estimation of 3,902,948 (95% CI 3,537,760-4,256,724) asymptomatic infected individuals.

Conclusions

Nearly one in three individuals were exposed to SARS-CoV-2 in the studied cities by March 2021. The seroprevalence increased about two-fold between April, 2020, and March, 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13464-7.

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Most cited references 36

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

Marina Pollán, Beatriz Pérez-Gómez, Roberto Pastor-Barriuso … (2020)

Summary 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 35 883 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, 61 075 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. Funding Spanish Ministry of Health, Institute of Health Carlos III, and Spanish National Health System.

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Bootstrap Methods: Another Look at the Jackknife

B Efron (1979)

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Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study

Katherine A. Twohig, Tommy Nyberg, Asad Zaidi … (2021)

Background The SARS-CoV-2 delta (B.1.617.2) variant was first detected in England in March, 2021. It has since rapidly become the predominant lineage, owing to high transmissibility. It is suspected that the delta variant is associated with more severe disease than the previously dominant alpha (B.1.1.7) variant. We aimed to characterise the severity of the delta variant compared with the alpha variant by determining the relative risk of hospital attendance outcomes. Methods This cohort study was done among all patients with COVID-19 in England between March 29 and May 23, 2021, who were identified as being infected with either the alpha or delta SARS-CoV-2 variant through whole-genome sequencing. Individual-level data on these patients were linked to routine health-care datasets on vaccination, emergency care attendance, hospital admission, and mortality (data from Public Health England's Second Generation Surveillance System and COVID-19-associated deaths dataset; the National Immunisation Management System; and NHS Digital Secondary Uses Services and Emergency Care Data Set). The risk for hospital admission and emergency care attendance were compared between patients with sequencing-confirmed delta and alpha variants for the whole cohort and by vaccination status subgroups. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar week, and vaccination status. Findings Individual-level data on 43 338 COVID-19-positive patients (8682 with the delta variant, 34 656 with the alpha variant; median age 31 years [IQR 17–43]) were included in our analysis. 196 (2·3%) patients with the delta variant versus 764 (2·2%) patients with the alpha variant were admitted to hospital within 14 days after the specimen was taken (adjusted hazard ratio [HR] 2·26 [95% CI 1·32–3·89]). 498 (5·7%) patients with the delta variant versus 1448 (4·2%) patients with the alpha variant were admitted to hospital or attended emergency care within 14 days (adjusted HR 1·45 [1·08–1·95]). Most patients were unvaccinated (32 078 [74·0%] across both groups). The HRs for vaccinated patients with the delta variant versus the alpha variant (adjusted HR for hospital admission 1·94 [95% CI 0·47–8·05] and for hospital admission or emergency care attendance 1·58 [0·69–3·61]) were similar to the HRs for unvaccinated patients (2·32 [1·29–4·16] and 1·43 [1·04–1·97]; p=0·82 for both) but the precision for the vaccinated subgroup was low. Interpretation This large national study found a higher hospital admission or emergency care attendance risk for patients with COVID-19 infected with the delta variant compared with the alpha variant. Results suggest that outbreaks of the delta variant in unvaccinated populations might lead to a greater burden on health-care services than the alpha variant. Funding Medical Research Council; UK Research and Innovation; Department of Health and Social Care; and National Institute for Health Research.

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Author and article information

Contributors

Reza Malekzadeh: dr.reza.malekzadeh@gmail.com

Journal

Journal ID (nlm-ta): BMC Public Health

Journal ID (iso-abbrev): BMC Public Health

Title: BMC Public Health

Publisher: BioMed Central (London )

ISSN (Electronic): 1471-2458

Publication date (Electronic): 23 May 2022

Publication date PMC-release: 23 May 2022

Publication date Collection: 2022

Volume: 22

Electronic Location Identifier: 1031

Affiliations

[1 ]GRID grid.411705.6, ISNI 0000 0001 0166 0922, Digestive Diseases Research Center, Digestive Diseases Research Institute, Shariati Hospital, , Tehran University of Medical Sciences, ; Tehran, 14117–13135 Iran

[2 ]GRID grid.411705.6, ISNI 0000 0001 0166 0922, Liver and Pancreatobiliary Diseases Research Center, Digestive Diseases Research Institute, Shariati Hospital, , Tehran University of Medical Sciences, ; Tehran, Iran

[3 ]GRID grid.411746.1, ISNI 0000 0004 4911 7066, Research Center for Addiction and Risky Behaviors (ReCARB), Psychosocial Health Research Institute, , Iran University of Medical Sciences, ; Tehran, Iran

[4 ]GRID grid.411746.1, ISNI 0000 0004 4911 7066, Department of Epidemiology, School of Public Health, , Iran University of Medical Sciences, ; Tehran, Iran

[5 ]GRID grid.411583.a, ISNI 0000 0001 2198 6209, Pharmaceutical Research Center, Pharmaceutical Technology Institute, , Mashhad University of Medical Sciences, ; Mashhad, Iran

[6 ]GRID grid.412571.4, ISNI 0000 0000 8819 4698, Microbiology Department, Burn & Wound Healing Research Center, , Shiraz University of Medical Sciences, ; Shiraz, Iran

[7 ]GRID grid.412888.f, ISNI 0000 0001 2174 8913, Liver and Gastrointestinal Diseases Research Center, , Tabriz University of Medical Sciences, ; Tabriz, Iran

[8 ]GRID grid.411623.3, ISNI 0000 0001 2227 0923, Department of Biostatistics, Health Sciences Research Center, Addiction Institute, Faculty of Health, , Mazandaran University of Medical Sciences, ; Sari, Iran

[9 ]GRID grid.411230.5, ISNI 0000 0000 9296 6873, Hearing Research Center, , Ahvaz Jundishapur University of Medical Sciences, ; Ahvaz, Iran

[10 ]GRID grid.411950.8, ISNI 0000 0004 0611 9280, Department of Epidemiology, School of Public Health, , Hamadan University of Medical Sciences, ; Hamadan, Iran

[11 ]GRID grid.411600.2, Department of Epidemiology, School of Public Health & Safety, , Shahid Beheshti University of Medical Sciences, ; Tehran, Iran

[12 ]Research Center for Environmental Determinants of Health, School of Public Health, Kermanshah UMS, Kermanshah, Iran

[13 ]GRID grid.412763.5, ISNI 0000 0004 0442 8645, Social Determinants of Health Center, , Urmia University of Medical Sciences, ; Urmia, Iran

[14 ]GRID grid.484406.a, ISNI 0000 0004 0417 6812, Kurdistan University of Medical Sciences, ; Sanandaj, Iran

[15 ]GRID grid.444830.f, ISNI 0000 0004 0384 871X, Gastroenterology and Hepatology Disease Research Center, , Qom University of Medical Science, ; Qom, Iran

[16 ]GRID grid.411746.1, ISNI 0000 0004 4911 7066, Department of Internal Medicine, School of Medicine, Gastrointestinal and Liver Diseases Research Center, , Iran University of Medical Sciences, ; Tehran, Iran

[17 ]GRID grid.411426.4, ISNI 0000 0004 0611 7226, Digestive Disease Research Center, , Ardabil University of Medical Sciences, ; Ardabil, Iran

[18 ]GRID grid.411495.c, ISNI 0000 0004 0421 4102, Social Determinants of Health Research Center, Health Research Institute, , Babol University of Medical Sciences, ; Babol, Iran

[19 ]GRID grid.488433.0, ISNI 0000 0004 0612 8339, Health Promotion Research Center, , Zahedan University of Medical Sciences, ; Zahedan, Iran

[20 ]GRID grid.412105.3, ISNI 0000 0001 2092 9755, HIV/STI Surveillance Research Center and WHO Collaborating Center for HIV Surveillance, Institute for Futures Studies in Health, , Kerman University of Medical Sciences, ; Kerman, Iran

[21 ]GRID grid.411747.0, ISNI 0000 0004 0418 0096, Golestan Research Center of Gastroenterology and Hepatology, , Golestan University of Medical Sciences, ; Gorgan, Iran

[22 ]GRID grid.411874.f, ISNI 0000 0004 0571 1549, Division of Gastroenterology & Hepatology, Gastrointestinal & Liver Diseases Research Center, , Guilan University of Medical Sciences, ; Rasht, Iran

[23 ]GRID grid.411874.f, ISNI 0000 0004 0571 1549, Gastrointestinal and Liver Diseases Research Center, , Guilan University of Medical Sciences, ; Rasht, Iran

[24 ]GRID grid.411705.6, ISNI 0000 0001 0166 0922, Digestive Oncology Research Center, Digestive Diseases Research Institute, Shariati Hospital, , Tehran University of Medical Sciences, ; Tehran, Iran

[25 ]GRID grid.248762.d, ISNI 0000 0001 0702 3000, Cancer Control Research, , BC Cancer Research Centre, ; Vancouver, BC Canada

Article

Publisher ID: 13464

DOI: 10.1186/s12889-022-13464-7

PMC ID: 9125542

PubMed ID: 35606743

SO-VID: 30cef9e8-608e-4ce9-8661-33eb4b40e266

License:

Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

History

Date received : 9 February 2022

Date accepted : 18 May 2022

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ScienceOpen disciplines: Public health

Keywords: covid-19,sars-cov-2,seroprevalence,general population,infection

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ScienceOpen disciplines: Public health

Keywords: covid-19, sars-cov-2, seroprevalence, general population, infection

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Seroprevalence of SARS-CoV-2 antibody among urban Iranian population: findings from the second large population-based cross-sectional study

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Abstract

Background

Methods

Results

Conclusions

Supplementary Information

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Novel Coronavirus Disease COVID-19

Most cited references 36

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

Bootstrap Methods: Another Look at the Jackknife

Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study

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