Estimation of the asymptomatic ratio of novel coronavirus infections (COVID-19)

Nishiura, Hiroshi; Kobayashi, Tetsuro; Miyama, Takeshi; Suzuki, Ayako; Jung, Sung mok; Hayashi, Katsuma; Kinoshita, Ryô; Yang, Yichi; Yuan, Baoyin; Akhmetzhanov, Andrei R.; Linton, Natalie M.

doi:10.1016/j.ijid.2020.03.020

Cited by 1,073 publications

(592 citation statements)

References 7 publications

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“…We can also have an idea about this fraction from the manifestation index (RKI Steckbrief 2020). The manifestation index describes the proportion of those infected who actually fall ill. Three studies from different settings (cruise ship outbreak, evacuated returning travellers, contact-based case search) gave figures of 51% (Mizumoto et al 2020), 69% (Nishiura et al 2020b) and 81% (Bi et al 2020). Hence, in a scenario where extensive tests are not performed and contacts are not traced properly, this fraction could be higher.…”

Section: ϑ (Fraction U/h)mentioning

confidence: 99%

Development of the reproduction number from coronavirus SARS-CoV-2 case data in Germany and implications for political measures

Khailaie

Mitra

Bandyopadhyay

et al. 2020

Preprint

158

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The novel Coronavirus SARS-CoV-2 (CoV) has induced a world-wide pandemic and subsequent non-pharmaceutical interventions (NPI) in order to control the spreading of the virus. NPIs are considered to be critical in order to at least delay the peak number of infected individuals and to prevent the health care system becoming overwhelmed by the number of patients to treat in hospitals or in intensive care units (ICUs). However, there is also increasing concern that the NPIs in place would increase mortality because of other diseases, increase the frequency of suicide and increase the risk of an economic recession with unforeseeable implications. It is therefore instrumental to evaluate the necessity of NPIs and to monitor the progress of containment of the virus spreading.

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Section: ϑ (Fraction U/h)mentioning

confidence: 99%

Development of the reproduction number from coronavirus SARS-CoV-2 case data in Germany and implications for political measures

Khailaie

Mitra

Bandyopadhyay

et al. 2020

Preprint

158

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“…We assumed a basic reproduction number for symptomatic cases of R 0 =2.5 [6,26], and a 14 day period from symptoms to recovery [27]. Estimates for the proportion of asymptomatic cases vary considerably; including 18% based on data from the Diamond Princess cruise ship (with a high proportion of elderly people) [28], 25% according to the director of the US CDC [29], 30% based on Japanese evacuees from Wuhan [30], and even up to 78% based on limited reporting from China [31]. Given the importance of this parameter in determining allocation of resources, we allowed this parameter to vary over a plausible range.…”

Section: Methodsmentioning

confidence: 99%

Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic

Worby

Chang

2020

Preprint

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The ongoing novel coronavirus disease pandemic has rapidly spread in early 2020, causing tens of thousands of deaths, over a million cases and widespread socioeconomic disruption. With no vaccine available and numerous national healthcare systems reaching or exceeding capacity, interventions to limit transmission are urgently needed. While there is broad agreement that travel restrictions and closure of non-essential businesses and schools are beneficial in limiting local and regional spread, recommendations around the use of face masks for the general population are less consistent internationally. In this study, we examined the role of face masks in mitigating the spread of COVID-19 in the general population, using epidemic models to estimate the total reduction of infections and deaths under various scenarios. In particular, we examined the optimal deployment of face masks when resources are limited, and explored a range of supply and demand dynamics. We found that face masks, even with a limited protective effect, can reduce infections and deaths, and can delay the peak time of the epidemic. We consistently found that a random distribution of masks in the population was a suboptimal strategy when resources were limited. Prioritizing coverage among the elderly was more beneficial, while allocating a proportion of available resources for diagnosed infected cases provided further mitigation under a range of scenarios. In summary, face mask use, particularly for a pathogen with relatively common asymptomatic carriage, can effectively provide some mitigation of transmission, while balancing provision between vulnerable healthy persons and symptomatic persons can optimize mitigation efforts when resources are limited.

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“…11 As is widely documented and reported (see e.g. Nishiura et al, 2020), there is also a ‡ow of individuals that are infected but do not display any symptoms. We denote this ‡ow by the transition rate 14 is related to 12 in the following sense,…”

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confidence: 90%

Projecting the Spread of COVID19 for Germany

Donsimoni

Glawion²,

Plachter

et al. 2020

Preprint

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We model the evolution of the number of individuals that are reported to be sick with COVID-19 in Germany. Our theoretical framework builds on a continuous time Markov chain with four states: healthy without infection, sick, healthy after recovery or after infection but without symptoms and dead. Our quantitative solution matches the number of sick individuals up to the most recent observation and ends with a share of sick individuals following from infection rates and sickness probabilities. We employ this framework to study inter alia the expected peak of the number of sick individuals in a scenario without public regulation of social contacts. We also study the e¤ects of public regulations. For all scenarios we report the expected end of the CoV-2 epidemic.We have four general …ndings: First, current epidemiological thinking implies that the long-run e¤ects of the epidemic only depend on the aggregate long-run infection rate and on the individual risk to turn sick after an infection. Any measures by individuals and the public therefore only in ‡uence the dynamics of spread of CoV-2. Second, predictions about the duration and level of the epidemic must strongly distinguish between the o¢ cially reported numbers (Robert Koch Institut, RKI) and actual numbers of sick individuals. Third, given the current (scarce) medical knowledge about long-run infection rate and individual risks to turn sick, any prediction on the length (duration in months) and strength (e.g. maximum numbers of sick individuals on a given day) is subject to a lot of uncertainty. Our predictions therefore o¤er robustness analyses that provide ranges on how long the epidemic will last and how strong it will be. Fourth, public interventions that are already in place and that are being discussed can lead to more and less severe outcomes of the epidemic. If an intervention takes place too early, the epidemic can actually be stronger than with an intervention that starts later. Interventions should therefore be contingent on current infection rates in regions or countries. of the modelling initiative of the Deutsche Gesellschaft für Epidemiologie for comments and discussions. We are deeply indebted to Damir Stijepic for the initial numerical solutions and the initial calibration. Our biggest debt of gratitude is owed to Matthias Birkner who has been advising and teaching us on stochastic models for many years. : medRxiv preprint over, will lie between 500 thousand and 5 million individuals. While this seems to be an absurd large range for a precise projection, this re ‡ects the uncertainty about the long-run infection rate in Germany. If we assume that Germany will follow the good scenario of Hubei (and we are even a bit more conservative given discussions about data quality), we will end up with 500 thousand sick individuals over the entire epidemic. If by contrast we believe (as many argue) that once the epidemic is over 70% of the population will have been infected (and thereby immune), we will end up at 5 million cases.De…ning the end of the epi...

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Estimation of the asymptomatic ratio of novel coronavirus infections (COVID-19)

Cited by 1,073 publications

References 7 publications

Development of the reproduction number from coronavirus SARS-CoV-2 case data in Germany and implications for political measures

Development of the reproduction number from coronavirus SARS-CoV-2 case data in Germany and implications for political measures

Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic

Projecting the Spread of COVID19 for Germany

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