Real Asymptomatic SARS-CoV-2 Infection Might be Rare: the Importance of Careful Interviews and Follow-up

Jeong, Tae Heum; Pak, Chuiyong; Ock, Minsu; Lee, Seock-Hwan; Son, Joung Sik; Jeon, Young Jee

doi:10.3346/jkms.2020.35.e333

Cited by 16 publications

(12 citation statements)

References 21 publications

(38 reference statements)

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“…These studies included a total of 104,058 laboratory-confirmed COVID-19 cases, of which 25,050 exhibited no symptoms at the time of testing and 7,220 remained asymptomatic. We identified 170 studies that reported asymptomatic infections ( 11 – 13 , 17 – 183 ), 332 studies that reported silent infections at the time of testing ( 10 – 12 , 14 , 17 – 20 , 23 – 27 , 31 , 32 , 35 – 40 , 42 – 44 , 46 , 47 , 49 , 50 , 52 , 53 , 56 – 58 , 60 – 66 , 68 , 69 , 73 – 75 , 77 – 79 , 81 , 84 , 87 , 90 – 94 , 97 , 99 , 101 , 103 , 104 , 106 , 111 , 113 – 116 , 118 , 119 , 121 – 123 , 125 , 127 , 128 , …”

Section: Resultsmentioning

confidence: 99%

Asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis

Sah

Fitzpatrick

Zimmer

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

381

351

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Quantification of asymptomatic infections is fundamental for effective public health responses to the COVID-19 pandemic. Discrepancies regarding the extent of asymptomaticity have arisen from inconsistent terminology as well as conflation of index and secondary cases which biases toward lower asymptomaticity. We searched PubMed, Embase, Web of Science, and World Health Organization Global Research Database on COVID-19 between January 1, 2020 and April 2, 2021 to identify studies that reported silent infections at the time of testing, whether presymptomatic or asymptomatic. Index cases were removed to minimize representational bias that would result in overestimation of symptomaticity. By analyzing over 350 studies, we estimate that the percentage of infections that never developed clinical symptoms, and thus were truly asymptomatic, was 35.1% (95% CI: 30.7 to 39.9%). At the time of testing, 42.8% (95% prediction interval: 5.2 to 91.1%) of cases exhibited no symptoms, a group comprising both asymptomatic and presymptomatic infections. Asymptomaticity was significantly lower among the elderly, at 19.7% (95% CI: 12.7 to 29.4%) compared with children at 46.7% (95% CI: 32.0 to 62.0%). We also found that cases with comorbidities had significantly lower asymptomaticity compared to cases with no underlying medical conditions. Without proactive policies to detect asymptomatic infections, such as rapid contact tracing, prolonged efforts for pandemic control may be needed even in the presence of vaccination.

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Section: Resultsmentioning

confidence: 99%

Asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis

Sah

Fitzpatrick

Zimmer

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

381

351

View full text Add to dashboard Cite

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“…A characteristic feature of coronaviral infection is a large number of asymptomatic individuals [ 53 , 54 ]. It is known that those with asymptomatic forms of infection not only do not significantly help in the formation of herd immunity, but often actually pose a risk (by participating in pathogen transmission and spread) [ 55 ].…”

Section: Methodsmentioning

confidence: 99%

SARS-CoV-2 Seroprevalence Structure of the Russian Population during the COVID-19 Pandemic

Popova

Смирнов

Андреева

et al. 2021

Viruses

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The SARS-CoV-2 pandemic, which came to Russia in March 2020, is accompanied by morbidity level changes and can be tracked using serological monitoring of a representative population sample from Federal Districts (FDs) and individual regions. In a longitudinal cohort study conducted in 26 model regions of Russia, distributed across all FDs, we investigated the distribution and cumulative proportions of individuals with antibodies (Abs) to the SARS-CoV-2 nucleocapsid antigen (Ag), in the period from June to December 2020, using a three-phase monitoring process. In addition, during the formation of the cohort of volunteers, the number of seropositive convalescents, persons who had contact with patients or COVID-19 convalescents, and the prevalence of asymptomatic forms of infection among seropositive volunteers were determined. According to a uniform methodology, 3 mL of blood was taken from the examined individuals, and plasma was separated, from which the presence of Abs to nucleocapsid Ag was determined on a Thermo Scientific Multiascan FC device using the “ELISA anti-SARS-CoV-2 IgG” reagent set (prod. Scientific Center for Applied Microbiology and Biotechnology), in accordance with the developer’s instructions. Volunteers (74,158) were surveyed and divided into seven age groups (1–17, 18–29, 30–39, 40–49, 59–59, 60–69, and 70+ years old), among whom 14,275 were identified as having antibodies to SARS-CoV-2. The average percent seropositive in Russia was 17.8% (IQR: 8.8–23.2). The largest proportion was found among children under 17 years old (21.6% (IQR: 13.1–31.7). In the remaining groups, seroprevalence ranged from 15.6% (IQR: 8–21.1) to 18.0% (IQR: 13.4–22.6). During monitoring, three (immune) response groups were found: (A) groups with a continuous increase in the proportion of seropositive; (B) those with a slow rate of increase in seroprevalence; and (C) those with a two-phase curve, wherein the initial increase was replaced by a decrease in the percentage of seropositive individuals. A significant correlation was revealed between the number of COVID-19 convalescents and contact persons, and between the number of contacts and healthy seropositive volunteers. Among the seropositive volunteers, more than 93.6% (IQR: 87.1–94.9) were asymptomatic. The results show that the COVID-19 pandemic is accompanied by an increase in seroprevalence, which may be important for the formation of herd immunity.

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“…Although many asymptomatic cases have been reported, 33 studies that have followed up such cases have been limited and small in sample size. [34][35][36][37][38][39] In China, 17/24 cases (70%) asymptomatic at detection developed symptoms or abnormal findings on computed tomography (CT) scans, although none of them developed severe outcomes. 34 In Italy, it was reported that mild symptoms developed in 2/5 (40%) asymptomatic cases, 35 whereas in New York, 10/14 (71%) asymptomatic pregnant women developed disease, of which two (14%) required admission to the ICU.…”

Section: A C C E P T E D V E R S I O Nmentioning

confidence: 99%