#Population Point #Prevalence of #SARS-CoV-2 Infection Based on a Statewide Random Sample — #Indiana, April 25–29, 2020 (MMWR Morb Mortal Wkly Rep., abstract)

[Source: US Centers for Disease Control and Prevention (CDC), MMWR Morbidity and Mortality Weekly Report, full page: (LINK). Abstract, edited.]

Population Point Prevalence of SARS-CoV-2 Infection Based on a Statewide Random Sample — Indiana, April 25–29, 2020

Early Release / July 21, 2020 / 69

Nir Menachemi, PhD1,2; Constantin T. Yiannoutsos, PhD1; Brian E. Dixon, PhD1,2; Thomas J. Duszynski, MPH1; William F. Fadel, PhD1; Kara K. Wools-Kaloustian, MD3; Nadia Unruh Needleman, MS1; Kristina Box, MD4; Virginia Caine, MD5; Connor Norwood, PhD6; Lindsay Weaver, MD4; Paul K. Halverson, DrPH1

Corresponding author: Nir Menachemi, nirmena@iu.edu.

1Indiana University Richard M. Fairbanks School of Public Health, Indianapolis, Indiana; 2Regenstrief Institute, Inc., Indianapolis, Indiana; 3Indiana University School of Medicine, Indianapolis, Indiana; 4Indiana State Department of Health; 5Marion County Department of Public Health, Indianapolis, Indiana; 6Indiana Family and Social Services Administration.

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Nir Menachemi reports a grant from State of Indiana which funded this study. Virginia Caine reports that she is a member of the MMWR Editorial Board. Brian E. Dixon and William F. Fadel report grants from the Indiana State Department of Health. Paul K. Halverson reports a grant from the State of Indiana. No other potential conflicts of interest were disclosed.

Suggested citation for this article: Menachemi N, Yiannoutsos CT, Dixon BE, et al. Population Point Prevalence of SARS-CoV-2 Infection Based on a Statewide Random Sample — Indiana, April 25–29, 2020. MMWR Morb Mortal Wkly Rep. ePub: 21 July 2020. DOI: http://dx.doi.org/10.15585/mmwr.mm6929e1

 

Summary

  • What is already known about this topic?
    • No state has conducted a random sample study to determine the population prevalence of SARS-CoV-2 infection at a given point in time.
  • What is added by this report?
    • In a random sample of Indiana residents aged ≥12 years, the estimated prevalence of current or previous SARS-CoV-2 infection in late April 2020 was 2.79%. Among persons with active infection, 44% reported no symptoms.
  • What are the implications for public health practice?
    • The number of reported cases represents an estimated one of 10 infections. Given that many persons in Indiana remain susceptible, adherence to evidence-based public health mitigation measures (e.g., social distancing, consistent and correct use of face coverings, and hand hygiene) is needed to reduce surge in hospitalizations and prevent morbidity and mortality from COVID-19.

 

Abstract

Population prevalence of persons infected with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), varies by subpopulation and locality. U.S. studies of SARS-CoV-2 infection have examined infections in nonrandom samples (1) or seroprevalence in specific populations* (2), which are limited in their generalizability and cannot be used to accurately calculate infection-fatality rates. During April 25–29, 2020, Indiana conducted statewide random sample testing of persons aged ≥12 years to assess prevalence of active infection and presence of antibodies to SARS-CoV-2; additional nonrandom sampling was conducted in racial and ethnic minority communities to better understand the impact of the virus in certain racial and ethnic minority populations. Estimates were adjusted for nonresponse to reflect state demographics using an iterative proportional fitting method. Among 3,658 noninstitutionalized participants in the random sample survey, the estimated statewide point prevalence of active SARS-CoV-2 infection confirmed by reverse transcription–polymerase chain reaction (RT-PCR) testing was 1.74% (95% confidence interval [CI] = 1.10–2.54); 44.2% of these persons reported no symptoms during the 2 weeks before testing. The prevalence of immunoglobulin G (IgG) seropositivity, indicating past infection, was 1.09% (95% CI = 0.76–1.45). The overall prevalence of current and previous infections of SARS-CoV-2 in Indiana was 2.79% (95% CI = 2.02–3.70). In the random sample, higher overall prevalences were observed among Hispanics and those who reported having a household contact who had previously been told by a health care provider that they had COVID-19. By late April, an estimated 187,802 Indiana residents were currently or previously infected with SARS-CoV-2 (9.6 times higher than the number of confirmed cases [17,792]) (3), and 1,099 residents died (infection-fatality ratio = 0.58%). The number of reported cases represents only a fraction of the estimated total number of infections. Given the large number of persons who remain susceptible in Indiana, adherence to evidence-based public health mitigation and containment measures (e.g., social distancing, consistent and correct use of face coverings, and hand hygiene) is needed to reduce surge in hospitalizations and prevent morbidity and mortality from COVID-19.

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Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; Indiana; USA.

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Estimated #Community #Seroprevalence of #SARS-CoV-2 #Antibodies — Two #Georgia Counties, April 28–May 3, 2020 (MMWR Morb Mortal Wkly Rep., abstract)

[Source: US Centers for Disease Control and Prevention (CDC), MMWR Morbidity and Mortality Weekly Report, full page: (LINK). Abstract, edited.]

Estimated Community Seroprevalence of SARS-CoV-2 Antibodies — Two Georgia Counties, April 28–May 3, 2020

Early Release / July 21, 2020 / 69

Holly M. Biggs, MD1; Jennifer B. Harris, PhD1; Lucy Breakwell, PhD1; F. Scott Dahlgren, MSPH1; Glen R. Abedi, MPH1; Christine M. Szablewski, DVM2,3; Jan Drobeniuc, MD, PhD1; Nirma D. Bustamante, MD1,3; Olivia Almendares, MSPH1; Amy H. Schnall, MPH1; Zunera Gilani, PhD1; Tiffany Smith, MPH1; Laura Gieraltowski, PhD1; Jeffrey A. Johnson, PhD1; Kristina L. Bajema, MD1,3; Kelsey McDavid, MPH1; Ilana J. Schafer, DVM1; Vickie Sullivan, MPH1; Lili Punkova, MS1; Alexandra Tejada-Strop, MS1; Raiza Amiling, MPH1; Claire P. Mattison, MPH1; Margaret M. Cortese, MD1; S. Elizabeth Ford, MD2,4; Lynn A. Paxton, MD2,5; Cherie Drenzek, DVM2; Jacqueline E. Tate, PhD1; CDC Field Surveyor Team

Corresponding author: Holly M. Biggs, xdc6@cdc.gov.

1CDC COVID-19 Response Team; 2Georgia Department of Public Health; 3Epidemic Intelligence Service, CDC; 4DeKalb County Board of Health, Decatur, Georgia; 5Fulton County Board of Health, Atlanta, Georgia.

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Suggested citation for this article: Biggs HM, Harris JB, Breakwell L, et al. Estimated Community Seroprevalence of SARS-CoV-2 Antibodies — Two Georgia Counties, April 28–May 3, 2020. MMWR Morb Mortal Wkly Rep. ePub: 21 July 2020. DOI: http://dx.doi.org/10.15585/mmwr.mm6929e2

 

Summary

  • What is already known about this topic?
    • SARS-CoV-2 infection in persons who are asymptomatic or not tested might not be recognized by case-based and syndromic surveillance; therefore, the population prevalence of past infection might be unknown.
  • What is added by this report?
    • A community seroprevalence survey, conducted in two counties in metropolitan Atlanta during April 28–May 3, using a two-stage cluster sampling design and serologic testing, estimated that 2.5% of the population had antibodies to SARS-CoV-2.
  • What are the implications for public health practice?
    • Serologic surveillance can complement case-based and syndromic surveillance. At the time of this survey, most of the two-county population had not been previously infected with SARS-CoV-2, highlighting the importance of continued mitigation measures to prevent infection, including social distancing, consistent and correct use of face coverings, and hand hygiene.

 

Abstract

Transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), is ongoing in many communities throughout the United States. Although case-based and syndromic surveillance are critical for monitoring the pandemic, these systems rely on persons obtaining testing or reporting a COVID-19–like illness. Using serologic tests to detect the presence of SARS-CoV-2 antibodies is an adjunctive strategy that estimates the prevalence of past infection in a population. During April 28–May 3, 2020, coinciding with the end of a statewide shelter-in-place order, CDC and the Georgia Department of Public Health conducted a serologic survey in DeKalb and Fulton counties in metropolitan Atlanta to estimate SARS-CoV-2 seroprevalence in the population. A two-stage cluster sampling design was used to randomly select 30 census blocks in each county, with a target of seven participating households per census block. Weighted estimates were calculated to account for the probability of selection and adjusted for age group, sex, and race/ethnicity. A total of 394 households and 696 persons participated and had a serology result; 19 (2.7%) of 696 persons had SARS-CoV-2 antibodies detected. The estimated weighted seroprevalence across these two metropolitan Atlanta counties was 2.5% (95% confidence interval [CI] = 1.4–4.5). Non-Hispanic black participants more commonly had SARS-CoV-2 antibodies than did participants of other racial/ethnic groups (p<0.01). Among persons with SARS-CoV-2 antibodies, 13 (weighted % = 49.9; 95% CI = 24.4–75.5) reported a COVID-19–compatible illness,* six (weighted % = 28.2; 95% CI = 11.9–53.3) sought medical care for a COVID-19–compatible illness, and five (weighted % = 15.7; 95% CI = 5.1–39.4) had been tested for SARS-CoV-2 infection, demonstrating that many of these infections would not have been identified through case-based or syndromic surveillance. The relatively low seroprevalence estimate in this report indicates that most persons in the catchment area had not been infected with SARS-CoV-2 at the time of the survey. Continued preventive measures, including social distancing, consistent and correct use of face coverings, and hand hygiene, remain critical in controlling community spread of SARS-CoV-2.

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Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; USA; Georgia.

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#Seroprevalence of #Antibodies to #SARS-CoV-2 in 10 Sites in the #USA, March 23-May 12, 2020 (JAMA Intern Med., abstract)

[Source: JAMA Internal Medicine, full page: (LINK). Abstract, edited.]

Seroprevalence of Antibodies to SARS-CoV-2 in 10 Sites in the United States, March 23-May 12, 2020

Fiona P. Havers, MD, MHS1; Carrie Reed, PhD1; Travis Lim, DrPH1; Joel M. Montgomery, PhD1; John D. Klena, PhD1; Aron J. Hall, DVM1; Alicia M. Fry, MD1; Deborah L. Cannon, BS1; Cheng-Feng Chiang, PhD1; Aridth Gibbons, BS1; Inna Krapiunaya, MS1; Maria Morales-Betoulle, PhD1; Katherine Roguski, MPH1; Mohammad Ata Ur Rasheed, PhD1; Brandi Freeman, PhD1; Sandra Lester, PhD1; Lisa Mills, PhD1; Darin S. Carroll, PhD1; S. Michele Owen, PhD1; Jeffrey A. Johnson, PhD1; Vera Semenova, PhD1; Carina Blackmore, DVM2; Debra Blog, MD3; Shua J. Chai, MD4; Angela Dunn, MD5; Julie Hand, MSPH6; Seema Jain, MD7; Scott Lindquist, MD8; Ruth Lynfield, MD9; Scott Pritchard, MPH10; Theresa Sokol, MPH11; Lynn Sosa, MD12; George Turabelidze, MD13; Sharon M. Watkins, PhD14; John Wiesman, DrPH15; Randall W. Williams, MD16; Stephanie Yendell, DVM17; Jarad Schiffer, MS1; Natalie J. Thornburg, PhD1

Author Affiliations: 1 CDC COVID-19 Response Team, Centers for Disease Control and Prevention, Atlanta, Georgia; 2 Florida Department of Health, Tallahassee; 3 New York State Department of Health, Albany; 4 Division of State and Local Readiness, Centers for Disease Control and Prevention, Atlanta, Georgia; 5 Utah Department of Health, Salt Lake City; 6 Louisiana Department of Health, New Orleans; 7 California Department of Health, Richmond; 8 Washington State Department of Health, Tumwater; 9 Minnesota Department of Health, St Paul; 10 Florida Department of Health, Tallahassee; 11 Louisiana Department of Health, New Orleans; 12 Connecticut Department of Public Health, Hartford; 13 Missouri Department of Health and Senior Services, Jefferson City; 14 Pennsylvania Department of Health, Harrisburg; 15 Washington State Department of Health, Tumwater; 16 Missouri Department of Health and Senior Services, Jefferson City; 17 Minnesota Department of Health, St Paul

JAMA Intern Med. Published online July 21, 2020. doi:10.1001/jamainternmed.2020.4130

 

Key Points

  • Question  – What proportion of persons in 10 US sites had detectable antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from March 23 to May 12, 2020?
  • Findings  – In this cross-sectional study of 16 025 residual clinical specimens, estimates of the proportion of persons with detectable SARS-CoV-2 antibodies ranged from 1.0% in the San Francisco Bay area (collected April 23-27) to 6.9% of persons in New York City (collected March 23-April 1). Six to 24 times more infections were estimated per site with seroprevalence than with coronavirus disease 2019 (COVID-19) case report data.
  • Meaning  – For most sites, it is likely that greater than 10 times more SARS-CoV-2 infections occurred than the number of reported COVID-19 cases; most persons in each site, however, likely had no detectable SARS-CoV-2 antibodies.

 

Abstract

Importance  

Reported cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection likely underestimate the prevalence of infection in affected communities. Large-scale seroprevalence studies provide better estimates of the proportion of the population previously infected.

Objective  

To estimate prevalence of SARS-CoV-2 antibodies in convenience samples from several geographic sites in the US.

Design, Setting, and Participants  

This cross-sectional study performed serologic testing on a convenience sample of residual sera obtained from persons of all ages. The serum was collected from March 23 through May 12, 2020, for routine clinical testing by 2 commercial laboratory companies. Sites of collection were San Francisco Bay area, California; Connecticut; south Florida; Louisiana; Minneapolis-St Paul-St Cloud metro area, Minnesota; Missouri; New York City metro area, New York; Philadelphia metro area, Pennsylvania; Utah; and western Washington State.

Exposures  

Infection with SARS-CoV-2.

Main Outcomes and Measures  

The presence of antibodies to SARS-CoV-2 spike protein was estimated using an enzyme-linked immunosorbent assay, and estimates were standardized to the site populations by age and sex. Estimates were adjusted for test performance characteristics (96.0% sensitivity and 99.3% specificity). The number of infections in each site was estimated by extrapolating seroprevalence to site populations; estimated infections were compared with the number of reported coronavirus disease 2019 (COVID-19) cases as of last specimen collection date.

Results  

Serum samples were tested from 16 025 persons, 8853 (55.2%) of whom were women; 1205 (7.5%) were 18 years or younger and 5845 (36.2%) were 65 years or older. Most specimens from each site had no evidence of antibodies to SARS-CoV-2. Adjusted estimates of the proportion of persons seroreactive to the SARS-CoV-2 spike protein antibodies ranged from 1.0% in the San Francisco Bay area (collected April 23-27) to 6.9% of persons in New York City (collected March 23-April 1). The estimated number of infections ranged from 6 to 24 times the number of reported cases; for 7 sites (Connecticut, Florida, Louisiana, Missouri, New York City metro area, Utah, and western Washington State), an estimated greater than 10 times more SARS-CoV-2 infections occurred than the number of reported cases.

Conclusions and Relevance  

During March to early May 2020, most persons in 10 diverse geographic sites in the US had not been infected with SARS-CoV-2 virus. The estimated number of infections, however, was much greater than the number of reported cases in all sites. The findings may reflect the number of persons who had mild or no illness or who did not seek medical care or undergo testing but who still may have contributed to ongoing virus transmission in the population.

Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; USA.

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#Serosurvey of #SARS-CoV-2 among #hospital #visitors in #China (Cell Res., summary)

[Source: Cell Research, full page: (LINK). Summary, edited.]

Serosurvey of SARS-CoV-2 among hospital visitors in China

Wenhua Liang, Yongping Lin, Jianping Bi, Jianfu Li, Ying Liang, Sook-San Wong, Mark Zanin, Zifeng Yang, Caichen Li, Ran Zhong, Guowu Jiang, Guang Han, Desheng Hu, Jianxing He & Nanshan Zhong

Cell Research (2020)

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Dear Editor, In China, the epidemic of COVID-19 has been temporarily brought under control due to strong measures, while there are few new cases except some imported ones (https://static.wecity.qq.com/wuhan-haiwai-pre/dist/index.html#/). The PCR-based test result combined with clinical symptoms has widely been used for the detection and confirmation of COVID-19.1 However, the prevalence of asymptomatic or subclinical SARS-CoV-2 infection in China remained unknown.

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Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; China; Nosocomial outbreaks.

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#SARS-CoV-2 #IgG #seroprevalence in #blood #donors located in three different federal states, #Germany, March to June 2020 (Euro Surveill., abstract)

[Source: Eurosurveillance, full page: (LINK). Abstract, edited.]

SARS-CoV-2 IgG seroprevalence in blood donors located in three different federal states, Germany, March to June 2020

Bastian Fischer1 , Cornelius Knabbe1 , Tanja Vollmer1

Affiliations: 1 Herz- und Diabeteszentrum NRW, Institut für Laboratoriums- und Transfusionsmedizin, Bad Oeynhausen, Germany

Correspondence:  Bastian Fischer

Citation style for this article: Fischer Bastian , Knabbe Cornelius , Vollmer Tanja . SARS-CoV-2 IgG seroprevalence in blood donors located in three different federal states, Germany, March to June 2020. Euro Surveill. 2020;25(28):pii=2001285. https://doi.org/10.2807/1560-7917.ES.2020.25.28.2001285

Received: 26 Jun 2020;   Accepted: 14 Jul 2020

 

Abstract

Most cases of coronavirus disease 2019 are mild or asymptomatic. Therefore, many cases remain unrecorded. We determined seroprevalence of IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 3,186 regular blood donors in three German federal states between 9 March and 3 June 2020. The IgG seroprevalence was 0.91% (95% confidence interval (CI): 0.58–1.24) overall, ranging from 0.66% (95% CI: 0.13–1.19) in Hesse to 1.22% (95% CI: 0.33–2.10) in Lower-Saxony.

©  This work is licensed under a Creative Commons Attribution 4.0 International License.

Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; Germany.

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#Estimation without #Representation: Early #SARS-CoV-2 #Seroprevalence Studies and the Path Forward (J Infect Dis., abstract)

[Source: Journal of Infectious Diseases, full page: (LINK). Abstract, edited.]

Estimation without Representation: Early SARS-CoV-2 Seroprevalence Studies and the Path Forward

Bonnie E Shook-Sa, DrPH, Ross M Boyce, MD, MSc, Allison E Aiello, PhD

The Journal of Infectious Diseases, jiaa429, https://doi.org/10.1093/infdis/jiaa429

Published: 16 July 2020

 

Abstract

The recent development and regulatory approval of a variety of serological assays indicating the presence of antibodies against SARS-CoV-2 has led to rapid and widespread implementation of seroprevalence studies. Accurate estimates of seroprevalence are needed to model transmission dynamics and estimate mortality rates. Furthermore, seroprevalence levels in a population help guide policy surrounding re-opening efforts. The literature to date has focused heavily on issues surrounding the quality of seroprevalence tests and less on the sampling methods which ultimately drive the representativeness of resulting estimates. Seroprevalence studies based on convenience samples are being reported widely and extrapolated to larger populations for the estimation of total COVID-19 infections, comparisons of prevalence across geographic regions, and estimation of mortality rates. In this viewpoint, we discuss the pitfalls that can arise with the use of convenience samples and offer guidance for moving towards more representative and timely population estimates of COVID-19 seroprevalence.

address-based sampling, convenience samples, COVID- 19, sampling, seroprevalence, transmission

Issue Section: Perspectives

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Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence.

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Lower #prevalence of #antibodies neutralizing #SARS-CoV-2 in group O #French #blood #donors (Antiviral Res., abstract)

[Source: Antiviral Research, full page: (LINK). Abstract, edited.]

Antiviral Research | Available online 15 July 2020, 104880 | In Press, Journal Pre-proof | Short Communication

Lower prevalence of antibodies neutralizing SARS-CoV-2 in group O French blood donors

Pierre Gallian 1,2,a, Boris Pastorino 1,a, Pascal Morel 2, Jacques Chiaroni 3,4, Laetitia Ninove 1, Xavier de Lamballerie 1

1 Unité des Virus Émergents, (UVE: Aix-Marseille Univ-IRD 190-INSERM 1207-IHU Méditerranée Infection), Marseille, France; 2 Établissement Français Du Sang, La Plaine, St Denis, France; 3 Établissement Français Du Sang, Provence Alpes Côte D’Azur et Corse, Marseille, France; 4 «Biologie des Groupes Sanguins», Aix Marseille Univ-CNRS-EFS-ADÉS, Marseille, France

Received 18 May 2020, Revised 3 July 2020, Accepted 8 July 2020, Available online 15 July 2020.

DOI: https://doi.org/10.1016/j.antiviral.2020.104880

 

Highlights

  • Antibodies neutralizing SARS-CoV-2 are fond with similar prevalence in men and women among French blood donors.
  • Virus infection may occur at similar incidence in men and women, while severe forms are more frequent in men.
  • Blood group O persons are less at risk of being infected by SARS-CoV-2 than other blood groups persons.

 

Abstract

We investigated the distribution of antibodies neutralizing SARS-CoV-2 according to age, sex or blood group in French blood donors. In 464 samples collected before the emergence of SARS-CoV-2 (2017 and 2018), our virus neutralization assay had a 100% specificity. It was used to test 998 samples collected from blood donors during the last week of March or the first week of April 2020. As expected at this stage of the outbreak, the prevalence was low (2.7%) and, importantly, criteria for blood donation imply that the vast majority of seropositives had asymptomatic or pauci-symptomatic SARS-CoV-2 infections. Seroprevalence values did not differ significantly among age groups (but were slightly higher in donors <30yo and ≥60yo), and between males and females (2.82% vs 2.69%), unlike what has been observed regarding hospitalizations admission to ICU and death rates in France. By contrast, we observed that the proportion of seropositives was significantly lower in group O donors (1.32% vs 3.86% in other donors, p=0.014). We conclude that virus infection seems to occur with a similar incidence in men and women among French blood donors, but that blood group O persons are less at risk of being infected and not only of suffering from severe clinical presentations, as previously suggested.

Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; France.

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Pandemic #peak #SARS-CoV-2 infection and #seroconversion #rates in #London frontline #HCWs (Lancet, summary)

[Source: Lancet, full page: (LINK). Summary, edited.]

Pandemic peak SARS-CoV-2 infection and seroconversion rates in London frontline health-care workers

Catherine F Houlihan, Nina Vora, Thomas Byrne, Dan Lewer, Gavin Kelly, Judith Heaney, Sonia Gandhi, Moira J Spyer, Rupert Beale, Peter Cherepanov, David Moore, Richard Gilson, Steve Gamblin, George Kassiotis, Laura E McCoy, Charles Swanton on behalf of the Crick COVID-19 Consortium, Andrew Hayward, Eleni Nastouli, on behalf of the SAFER Investigators †

Published: July 09, 2020 | DOI: https://doi.org/10.1016/S0140-6736(20)31484-7

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Nosocomial transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major public health concern. Health-care workers (HCWs) are at high risk of developing COVID-19, and may themselves contribute to transmission.1
To evaluate these risks, we enrolled 200 patient-facing HCWs between March 26 and April 8, 2020, in SARS-CoV-2 Acquisition in Frontline Healthcare Workers—Evaluation to inform Response (SAFER), a prospective cohort study in high-risk frontline HCWs in an acute National Health Service hospital trust in London. We collected nasopharyngeal swabs for RT-PCR twice per week, symptom data, and blood samples monthly for high-sensitivity serology assays (ELISA and flow cytometry for spike glycoprotein). Further methodology, study participant demographics, and the length of participation are described in the appendix.

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Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; Nosocomial Outbreaks; UK; HCWs.

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#SARS-CoV-2 #seroprevalence in #COVID19 #hotspots (Lancet, summary)

[Source: Lancet, full page: (LINK). Summary, edited.]

SARS-CoV-2 seroprevalence in COVID-19 hotspots

Isabella Eckerle, Benjamin Meyer

Published: July 06, 2020 | DOI: https://doi.org/10.1016/S0140-6736(20)31482-3

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has surprised the world  with its range of disease manifestations, from asymptomatic infection to critical illness  leading to hospital admission and death.1,  2  Due to the high proportion of  asymptomatic or mild infections (approximately 80%), data restricted to laboratory- confirmed cases do not capture the true extent of the spread or burden of the virus, or its  infection-fatality ratio.2 Therefore, serological detection of specific antibodies against  SARS-CoV-2 can better estimate the true number of infections. Due to co- circulation of other human coronaviruses, serology for SARS-CoV-2 is not trivial.  Antibody cross-reactivity with other human coronaviruses has been largely overcome by  using selected viral antigens, and several commercial assays are now available for  SARS-CoV-2 serology. However, despite high sensitivity and specificity, a setting with a  low pretest probability, such as current population-based seroprevalence studies,  warrants careful validation of results.3  Extensive previous assay validation in well characterised serum samples and confirmation of positive results are thus necessary to prevent false-positive findings from confounding seroprevalence rates.

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Keyword: SARS-CoV-2; COVID-19; Serology; Seroprevalence.

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

[Source: Lancet, full page: (LINK). Abstract, edited.]

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

Prof Marina Pollán, MD, Beatriz Pérez-Gómez, MD, Roberto Pastor-Barriuso, PhD, Jesús Oteo, PhD, Miguel A Hernán, MD, Mayte Pérez-Olmeda, PhD, Jose L Sanmartín, MEng, Aurora Fernández-García, PhD, Israel Cruz, PhD, Nerea Fernández de Larrea, MD, Marta Molina, MD, Francisco Rodríguez-Cabrera, MD, Mariano Martín, MEng, Paloma Merino-Amador, MD, Jose León Paniagua, PhD, Juan F Muñoz-Montalvo, MEng, Faustino Blanco, MD, Raquel Yotti, MD on behalf of the ENE-COVID Study Group †

Published: July 06, 2020 | DOI: https://doi.org/10.1016/S0140-6736(20)31483-5

 

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 (<3·1% by the point-of-care test). There was substantial geographical variability, with higher prevalence around Madrid (>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.

Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; Spain.

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