High prevalence of SARS-CoV-2 infection in repatriation flights to Greece from three European countries

Lytras, Theodore; Dellis, George; Flountzi, Anastasia; Hatzianastasiou, Sophia; Nikolopoulou, Georgia; Tsekou, Katerina; Diamantis, Zafiris; Stathopoulou, Grigoria; Togka, Marianthi; Gerolymatos, Gerasimos; Rigakos, George S.; Sapounas, Spiridon; Tsiodras, Sotirios

doi:10.1093/jtm/taaa054

Cited by 60 publications

(59 citation statements)

References 3 publications

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“…Of these, two reported on the same study population, 16 46 so we linked the records and used data from the most detailed report. 16 Data from 31 empirical studies were collected in nine countries: China (21 studies, 1672people); 17 19 20 22 25-27 30 31 34-44 48 Japan (two studies, 116) people; 16 33 United States of America (two studies, 66 people); 18 23 and one study each from France (13 people), 21 Germany (two people), 47 Greece (39 people), 45 Malaysia (four people), 32 Thailand (11 people), 29 Vietnam (6 people). 24 One statistical modelling study that used data collected from all 634 tested passengers on a cruise ship, the Diamond Princess, 28 was considered separately from a study that reported on a subset of 104 of the passengers who were hospitalised in Japan.…”

Section: Resultsmentioning

confidence: 99%

Asymptomatic SARS-CoV-2 infections: a living systematic review and meta-analysis

Buitrago-Garcia

Egli-Gany

Counotte

et al. 2020

Preprint

166

132

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 Review question 1. Amongst people who become infected with SARS-CoV-2, what proportion does not experience symptoms at all during their infection? Summary estimate 15% (95% confidence interval, CI 10 to 22%, prediction interval 3 to 55%, 28 studies, random effect model. Version 1, summary estimate 29% (95% confidence interval 23 to 37%, 8 studies, fixed effect model);  Review question 2. Amongst people with SARS-CoV-2 infection who are asymptomatic when diagnosed, what proportion will develop symptoms later? Fifteen studies included, no change in result;  Review question 3. What proportion of SARS-CoV-2 transmission is accounted for by people who are either asymptomatic throughout infection, or pre-symptomatic? Four studies included, no change in result; : medRxiv preprint modelling studies, 40-60% of all SARS-CoV-2 infections are the result of transmission from presymptomatic individuals, with a smaller contribution from asymptomatic individuals. CONCLUSIONAn intermediate contribution of pre-symptomatic and asymptomatic infections to overall SARS-CoV-2 transmission means that combination prevention measures, with enhanced hand and respiratory hygiene, testing tracing and isolation strategies and social distancing, will continue to be needed.The findings of this living systematic review of publications early in the pandemic suggests that most SARS-CoV-2 infections are not asymptomatic throughout the course of infection. ABSTRACT Structured summary2 Provide a structured summary including, as applicable: background; objectives; data sources; study eligibility criteria, participants, and interventions; study appraisal and synthesis methods; results; limitations; conclusions and implications of key findings; systematic review registration number. 2-3

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Section: Resultsmentioning

confidence: 99%

Asymptomatic SARS-CoV-2 infections: a living systematic review and meta-analysis

Buitrago-Garcia

Egli-Gany

Counotte

et al. 2020

Preprint

166

132

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“…In the largest cohort in our set (6), researchers in Iceland used the following 2 methods to screen the general population for SARS-CoV-2 infection: an open invitation for interested parties to register online then provide biosamples at a Reykjavik location, and a text message sent to "randomly chosen Icelanders between the ages 20 and 70 years" inviting them to participate in the same manner as the first group (Table) (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). In all, 13 080 persons volunteered for the screening, 100 (0.8%) of whom tested positive for SARS-CoV-2.…”

Section: Cohorts Icelandmentioning

confidence: 99%

“…From 20 through 25 March 2020, a total of 783 Greek citizens were repatriated from Spain, Turkey, and the United Kingdom on 7 flights. Forty (5.1%) tested positive for SARS-CoV-2 (14). At the time of testing, 39 (97.5%) were asymptomatic.…”

Section: Greek Citizens Evacuated From Spain Turkey and The Unitedmentioning

confidence: 99%

Prevalence of Asymptomatic SARS-CoV-2 Infection

Oran

Topol

2020

Annals of Internal Medicine

2,302

1,544

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly throughout the world since the first cases of coronavirus disease 2019 (COVID-19) were observed in December 2019 in Wuhan, China. It has been suspected that infected persons who remain asymptomatic play a significant role in the ongoing pandemic, but their relative number and effect have been uncertain. The authors sought to review and synthesize the available evidence on asymptomatic SARS-CoV-2 infection. Asymptomatic persons seem to account for approximately 40% to 45% of SARS-CoV-2 infections, and they can transmit the virus to others for an extended period, perhaps longer than 14 days. Asymptomatic infection may be associated with subclinical lung abnormalities, as detected by computed tomography. Because of the high risk for silent spread by asymptomatic persons, it is imperative that testing programs include those without symptoms. To supplement conventional diagnostic testing, which is constrained by capacity, cost, and its one-off nature, innovative tactics for public health surveillance, such as crowdsourcing digital wearable data and monitoring sewage sludge, might be helpful.

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“…The study of 565 Japanese citizens repatriated from China (26), found 13 positives: 4 asymptomatic and 9 symptomatic, based on screening on arrival. The other of 383 Greek citizens repatriated from UK, Spain, and Turkey (27) found 40 asymptomatic positives on arrival, 4 of whom later self-reported symptoms. Again, the likely initial exclusion of symptomatic people, and the lack of comprehensive follow up would both overestimate the asymptomatic rates.…”

Section: Rt-pcr = Reverse Transcription-polymerase Chain Reaction; Hcmentioning

confidence: 99%

Estimating the extent of asymptomatic COVID-19 and its potential for community transmission: Systematic review and meta-analysis

Byambasuren

Cardona

Bell

et al. 2020

Official Journal of the Association of Medical Microbiology and

478

395

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Background: Knowing the prevalence of true asymptomatic coronavirus disease 2019 (COVID-19) cases is critical for designing mitigation measures against the pandemic. We aimed to synthesize all available research on asymptomatic cases and transmission rates. Methods: We searched PubMed, Embase, Cochrane COVID-19 trials, and Europe PMC for primary studies on asymptomatic prevalence in which (1) the sample frame includes at-risk populations and (2) follow-up was sufficient to identify pre-symptomatic cases. Meta-analysis used fixed-effects and random-effects models. We assessed risk of bias by combination of questions adapted from risk of bias tools for prevalence and diagnostic accuracy studies. Results: We screened 2,454 articles and included 13 low risk-of-bias studies from seven countries that tested 21,708 at-risk people, of which 663 were positive and 111 asymptomatic. Diagnosis in all studies was confirmed using a real-time reverse transcriptase–polymerase chain reaction test. The asymptomatic proportion ranged from 4% to 41%. Meta-analysis (fixed effects) found that the proportion of asymptomatic cases was 17% (95% CI 14% to 20%) overall and higher in aged care (20%; 95% CI 14% to 27%) than in non-aged care (16%; 95% CI 13% to 20%). The relative risk (RR) of asymptomatic transmission was 42% lower than that for symptomatic transmission (combined RR 0.58; 95% CI 0.34 to 0.99, p = 0.047). Conclusions: Our one-in-six estimate of the prevalence of asymptomatic COVID-19 cases and asymptomatic transmission rates is lower than those of many highly publicized studies but still sufficient to warrant policy attention. Further robust epidemiological evidence is urgently needed, including in subpopulations such as children, to better understand how asymptomatic cases contribute to the pandemic.

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High prevalence of SARS-CoV-2 infection in repatriation flights to Greece from three European countries

Cited by 60 publications

References 3 publications

Asymptomatic SARS-CoV-2 infections: a living systematic review and meta-analysis

Asymptomatic SARS-CoV-2 infections: a living systematic review and meta-analysis

Prevalence of Asymptomatic SARS-CoV-2 Infection

Estimating the extent of asymptomatic COVID-19 and its potential for community transmission: Systematic review and meta-analysis

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