The Proportion of SARS-CoV-2 Infections That Are Asymptomatic

Oran, Daniel P; Topol, Eric J.

doi:10.7326/m20-6976

Cited by 524 publications

(458 citation statements)

References 62 publications

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“…39 % of all seropositive individuals in this study reported no COVID-19 like symptoms. This proportion corresponds to other studies that have reported this value in the range from 32,4 % in England to 57,2 % in Iran (2, 26, 27).…”

Section: Discussionsupporting

confidence: 89%

Rapid increase of SARS-CoV-2 seroprevalence during the 2020 pandemic year in the population of the city of Tirana, Albania

Sulçebe

Ylli

Cenko

et al. 2021

Preprint

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Introduction: While the identification of anti SARS-CoV-2 antibodies has been used to measure the hidden circulation of the COVID-19 in communities, there are few publications on the dynamics of SARS-CoV-2 seroprevalence during both waves of 2020. This study provides original data about the change in proportion of individuals showing immune response to COVID-19 between beginning of July and end of December 2020. Methods: The study was conducted in two rounds, 27 June -3 July, and 21-28 December 2020, using two independently selected samples of individuals 20-70 years old. Study participants were randomly selected from lists of the inhabitants of the catchment communities of four primary health care centers in Tirana City. Serological testing was performed by an ELISA method which determines IgG class antibodies anti S1 protein of SARS-CoV-2 virus. The validity of the method was tested in a sample of blood donors sera of 2018. Results: The proportion of individuals classified as seropositive during the first round, in early July was 7.5% (95% CI: 4.3% - 10.7%). The proportion rose sharply in the second round, by late December 2020, reaching 48.2% (95% CI: 44.8% - 51.7%). The same increasing pattern was observed in all studied categories. No statistical significance was found between men and women and between age categories. The prevalence of seropositive individuals was always significantly higher among those who reported symptoms and those who had done the molecular test. Conclusion: The ratio of total infected cases over confirmed cases was estimated to be higher than 10 to 1 in Albania. The rapid increase in SARS-CoV-2 seroprevalence observed in Tirana City may have been facilitated by a number of factors, including the very low infection exposure during the period March - May 2020, and the consecutive high susceptibility in population. Despite the observed high seroprevalence, one month after the study, COVID-19 incidence continued to increase in Tirana.

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Section: Discussionsupporting

confidence: 89%

Rapid increase of SARS-CoV-2 seroprevalence during the 2020 pandemic year in the population of the city of Tirana, Albania

Sulçebe

Ylli

Cenko

et al. 2021

Preprint

View full text Add to dashboard Cite

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“…However, participants were not followed up; therefore, we cannot determine if patients were truly asymptomatic or actually presymptomatic and developed symptoms subsequently. Current evidence from other longitudinal studies suggests that three-quarters of those with a PCR positive test in the absence of symptoms remain asymptomatic (Oran and Topol 2021). All dental settings where positive tests were detected were followed up by local health protection teams, and in all cases, assurances were given that IPC guidance had been followed.…”

Section: Discussionmentioning

confidence: 99%

SARS-CoV-2 Positivity in Asymptomatic-Screened Dental Patients

et al. 2021

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Enhanced community surveillance is a key pillar of the public health response to coronavirus disease 2019 (COVID-19). Asymptomatic carriage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a potentially significant source of transmission, yet remains relatively poorly understood. Disruption of dental services continues with significantly reduced capacity. Ongoing precautions include preappointment and/or at appointment COVID-19 symptom screening and use of enhanced personal protective equipment (PPE). This study aimed to investigate SARS-CoV-2 infection in dental patients to inform community surveillance and improve understanding of risks in the dental setting. Thirty-one dental care centers across Scotland invited asymptomatic-screened patients aged over 5 y to participate. Following verbal consent and completion of sociodemographic and symptom history questionnaire, trained dental teams took a combined oropharyngeal and nasal swab sample using standardized Viral Transport Medium–containing test kits. Samples were processed by the Lighthouse Lab and patients informed of their results by SMS/email with appropriate self-isolation guidance in the event of a positive test. All positive cases were successfully followed up by the national contact tracing program. Over a 13-wk period (from August 3, 2020, to October 31, 2020), 4,032 patients, largely representative of the population, were tested. Of these, 22 (0.5%; 95% CI, 0.5%–0.8%) tested positive for SARS-CoV-2. The positivity rate increased over the period, commensurate with uptick in community prevalence identified across all national testing monitoring data streams. To our knowledge, this is the first report of a COVID-19 testing survey in asymptomatic-screened patients presenting in a dental setting. The positivity rate in this patient group reflects the underlying prevalence in community at the time. These data are a salient reminder, particularly when community infection levels are rising, of the importance of appropriate ongoing infection prevention control and PPE vigilance, which is relevant as health care team fatigue increases as the pandemic continues. Dental settings are a valuable location for public health surveillance.

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“…One recent global systematic review of observational studies of SARS-CoV-2 that employed serologic or PCR testing found 18 prospective studies. 8 Most were focused on healthcare workers or other occupational groups, individuals in congregate settings, evacuees, or cruise ships; none were community-based (i.e., focused on risk factors in communities vs other higher risk populations/settings). 8 A greater understanding of SARS-CoV-2 incidence and risk factors in community samples can substantially complement routine case-based surveillance of new SARS-CoV-2 diagnoses and cross-sectional serosurveys, serving to inform aspects of implementation of the public health response and policies.…”

Section: Introductionmentioning

confidence: 99%

SARS-CoV-2 incidence and risk factors in a national, community-based prospective cohort of U.S. adults

Nash

Rane

Chang

et al. 2021

Preprint

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Background Epidemiologic risk factors for incident SARS-CoV-2 infection are best characterized via prospective cohort studies, complementing case-based surveillance and cross-sectional seroprevalence studies. Methods We estimated the cumulative incidence of SARS-CoV-2 infection and incidence rates of seroconversion in a national prospective online cohort of 6,745 U.S. adults, enrolled March-July 2020. A subset (n=4,459) underwent serologic testing (Bio-Rad Platelia Total Ab, IgA/IgM/IgG), offered initially May-September 2020 and again November 2020-January 2021. Results A total of 303 of 4,459 individuals showed serologic evidence of past SARS-CoV-2 infection (cumulative incidence of 6.8%; 95% Confidence Interval [CI] 6.1%-7.6% [6.3%, 95% CI 5.7%-7.1% adjusting for laboratory test error]). Among 3,280 initially seronegative participants with a subsequent serologic test, we observed 145 seroconversions during 1,562 person years of follow-up (incidence rate of 9.3 per 100 person-years [95% CI 17.9-11.0]). Racial/ethnic disparities in crude incidence rates were apparent through January 2021 (rate ratio [RRHispanic vs Whites]=2.1; 95% CI 1.4-3.1; RRnon-Hispanic Blacks vs Whites=1.8; 95% CI 0.96-3.1). Incidence was higher in the southern (RRSouth vs Northeast=1.7; 95% CI 1.1-2.8) and midwestern (RRMidwest vs Northeast=1.6; 95% CI 0.98-2.7) regions, in rural vs urban areas (RR=1.5; 95% CI 1.0-2.2), and among essential workers (RR=1.7; 95% CI 1.1-2.5). Household crowding (RR=1.6, 95% CI 1.1-2.3), dining indoors at restaurants/bars (RR=2.0; 95% CI 1.4-2.8), visiting places of worship (RR=2.0; 95% CI 1.3-2.9), wearing masks sometimes vs always while grocery shopping (RR=2.5; 95% CI 1.3-4.4), indoor visits with people outside the household with masks (RRalways mask vs no visit=2.6; 95% CI 1.6-4.4) and without masks (RRsometimes mask vs no visit=3.5; 95% CI 2.7-5.7; RRnever mask vs no visit=5.3; 95% CI 3.1-8.9); working indoors at a place of employment with masks (RRalways mask vs no in-person=2.0, 95% CI 1.4-2.8) and without masks (RRsometimes mask vs no in-person= 2.0, 95% CI 1.1-3.5; RRnever mask vs no in-person=3.7, 95% CI 1.3-8.5); attending a salon or gym with masks (RRalways mask vs no salon/gym=1.7 (95% CI 1.1-2.4), gathering indoors and outdoors in groups of >10 (RR=1.9, 95% CI 1.2-2.0); and air travel during the pandemic (RR=1.7; 95% CI 1.1-2.6) were also associated with higher incidence rates. Among 303 seropositive individuals, 27.4% had asymptomatic infection, and 32% reported a positive SARS-CoV-2 PCR test or provider diagnosis of COVID-19. In this group, there were major gaps in the coverage of public health interventions aimed at isolation (31% isolated) and contact tracing (asked about contacts [18%]; told about exposure to a confirmed case [7.6%]). Conclusions Modifiable risk factors and low reach of public health strategies drive SARS-CoV-2 transmission across the U.S. It is critical to address inequities in incidence, reduce risk factors, and improve the reach of public health strategies in the vaccine era.

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The Proportion of SARS-CoV-2 Infections That Are Asymptomatic

Cited by 524 publications

References 62 publications

Rapid increase of SARS-CoV-2 seroprevalence during the 2020 pandemic year in the population of the city of Tirana, Albania

Rapid increase of SARS-CoV-2 seroprevalence during the 2020 pandemic year in the population of the city of Tirana, Albania

SARS-CoV-2 Positivity in Asymptomatic-Screened Dental Patients

SARS-CoV-2 incidence and risk factors in a national, community-based prospective cohort of U.S. adults

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