COVID-19 antibody seroprevalence in Santa Clara County, California.
COVID-19
infection fatality rate
seroprevalence
Journal
International journal of epidemiology
ISSN: 1464-3685
Titre abrégé: Int J Epidemiol
Pays: England
ID NLM: 7802871
Informations de publication
Date de publication:
17 05 2021
17 05 2021
Historique:
received:
09
09
2020
accepted:
21
01
2021
pubmed:
23
2
2021
medline:
21
5
2021
entrez:
22
2
2021
Statut:
ppublish
Résumé
Measuring the seroprevalence of antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is central to understanding infection risk and fatality rates. We studied Coronavirus Disease 2019 (COVID-19)-antibody seroprevalence in a community sample drawn from Santa Clara County. On 3 and 4 April 2020, we tested 3328 county residents for immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies to SARS-CoV-2 using a rapid lateral-flow assay (Premier Biotech). Participants were recruited using advertisements that were targeted to reach county residents that matched the county population by gender, race/ethnicity and zip code of residence. We estimate weights to match our sample to the county by zip, age, sex and race/ethnicity. We report the weighted and unweighted prevalence of antibodies to SARS-CoV-2. We adjust for test-performance characteristics by combining data from 18 independent test-kit assessments: 14 for specificity and 4 for sensitivity. The raw prevalence of antibodies in our sample was 1.5% [exact binomial 95% confidence interval (CI) 1.1-2.0%]. Test-performance specificity in our data was 99.5% (95% CI 99.2-99.7%) and sensitivity was 82.8% (95% CI 76.0-88.4%). The unweighted prevalence adjusted for test-performance characteristics was 1.2% (95% CI 0.7-1.8%). After weighting for population demographics, the prevalence was 2.8% (95% CI 1.3-4.2%), using bootstrap to estimate confidence bounds. These prevalence point estimates imply that 53 000 [95% CI 26 000 to 82 000 using weighted prevalence; 23 000 (95% CI 14 000-35 000) using unweighted prevalence] people were infected in Santa Clara County by late March-many more than the ∼1200 confirmed cases at the time. The estimated prevalence of SARS-CoV-2 antibodies in Santa Clara County implies that COVID-19 was likely more widespread than indicated by the number of cases in late March, 2020. At the time, low-burden contexts such as Santa Clara County were far from herd-immunity thresholds.
Sections du résumé
BACKGROUND
Measuring the seroprevalence of antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is central to understanding infection risk and fatality rates. We studied Coronavirus Disease 2019 (COVID-19)-antibody seroprevalence in a community sample drawn from Santa Clara County.
METHODS
On 3 and 4 April 2020, we tested 3328 county residents for immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies to SARS-CoV-2 using a rapid lateral-flow assay (Premier Biotech). Participants were recruited using advertisements that were targeted to reach county residents that matched the county population by gender, race/ethnicity and zip code of residence. We estimate weights to match our sample to the county by zip, age, sex and race/ethnicity. We report the weighted and unweighted prevalence of antibodies to SARS-CoV-2. We adjust for test-performance characteristics by combining data from 18 independent test-kit assessments: 14 for specificity and 4 for sensitivity.
RESULTS
The raw prevalence of antibodies in our sample was 1.5% [exact binomial 95% confidence interval (CI) 1.1-2.0%]. Test-performance specificity in our data was 99.5% (95% CI 99.2-99.7%) and sensitivity was 82.8% (95% CI 76.0-88.4%). The unweighted prevalence adjusted for test-performance characteristics was 1.2% (95% CI 0.7-1.8%). After weighting for population demographics, the prevalence was 2.8% (95% CI 1.3-4.2%), using bootstrap to estimate confidence bounds. These prevalence point estimates imply that 53 000 [95% CI 26 000 to 82 000 using weighted prevalence; 23 000 (95% CI 14 000-35 000) using unweighted prevalence] people were infected in Santa Clara County by late March-many more than the ∼1200 confirmed cases at the time.
CONCLUSION
The estimated prevalence of SARS-CoV-2 antibodies in Santa Clara County implies that COVID-19 was likely more widespread than indicated by the number of cases in late March, 2020. At the time, low-burden contexts such as Santa Clara County were far from herd-immunity thresholds.
Identifiants
pubmed: 33615345
pii: 6146069
doi: 10.1093/ije/dyab010
pmc: PMC7928865
doi:
Substances chimiques
Antibodies, Viral
0
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
410-419Informations de copyright
© The Author(s) 2021. Published by Oxford University Press on behalf of the International Epidemiological Association.
Références
J Med Virol. 2020 Sep;92(9):1433
pubmed: 32320084
Lancet Infect Dis. 2020 Jul;20(7):774-775
pubmed: 32243815
JAMA. 2020 Jun 16;323(23):2425-2427
pubmed: 32421144
Bull World Health Organ. 2021 Jan 1;99(1):19-33F
pubmed: 33716331
Science. 2020 May 1;368(6490):489-493
pubmed: 32179701
Lancet. 2020 Sep 25;:
pubmed: 32987007
Diagn Microbiol Infect Dis. 2020 Nov;98(3):115128
pubmed: 32777699
J Med Internet Res. 2019 Aug 19;21(8):e14021
pubmed: 31429409
JAMA. 2020 May 12;323(18):1775-1776
pubmed: 32203977
N Engl J Med. 2020 May 21;382(21):2012-2022
pubmed: 32227758
Nat Med. 2020 Apr;26(4):506-510
pubmed: 32284616
Lancet Infect Dis. 2020 Jun;20(6):669-677
pubmed: 32240634
Lancet. 2020 Mar 28;395(10229):1014-1015
pubmed: 32197108
J Am Geriatr Soc. 2020 Aug;68(8):1653-1656
pubmed: 32484912
Ann Epidemiol. 2020 Aug;48:23-29.e4
pubmed: 32648546