Serial interval in determining the estimation of reproduction number of the novel coronavirus disease (COVID-19) during the early outbreak

Zhao, Shi; Cao, Peihua; Gao, Daozhou; Zhuang, Zian; Cai, Yongli; Ran, Jinjun; Chong, Ka Chun; Wang, Kai; Lou, Yijun; Wang, Weiming; Yang, Lin; He, Daihai; Wang, Maggie Haitian

doi:10.1093/jtm/taaa033

Cited by 50 publications

(47 citation statements)

References 6 publications

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“…The serial interval is the average duration between the infectious point (often symptom onset) of the index case and the symptom onset (or diagnosis) of secondary cases. Reported serial intervals vary significantly across different studies, with an average of 5 days[15,17,21,[31][32][33]. We adopt a conservative estimate of 6 days for young and 4 days for old people, ranging 3-10 days.…”

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confidence: 99%

Modeling Return of the Epidemic: Impact of Population Structure, Asymptomatic Infection, Case Importation and Personal Contacts

2020

Preprint

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Background: Proactive interventions have halted the pandemic of coronavirus infected disease in some regions. However, without reaching herd immunity, the return of epidemic is possible.We investigate the impact of population structure, case importation, asymptomatic cases, and the number of contacts on a possible second wave of epidemic through mathematical modelling.Methods: we built a modified Susceptible-exposed-Infectious-Removed (SEIR) model with parameters mirroring those of the COVID-19 pandemic and reported simulated characteristics of epidemics for incidence, hospitalizations and deaths under different scenarios. Results:A larger percent of old people leads to higher number of hospitalizations, while a large percent of prior infection will effectively curb the epidemic. The number of imported cases and the speed of importation have small impact on the epidemic progression. However, a higher percent of asymptomatic cases slows the epidemic down and reduces the number of hospitalizations and deaths at the epidemic peak. Finally, reducing the number of contacts among young people alone has moderate effects on themselves, but little effects on the old population.However, reducing the number of contacts among old people alone can mitigate the epidemic significantly in both groups, even though young people remain active within themselves.

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confidence: 99%

Modeling Return of the Epidemic: Impact of Population Structure, Asymptomatic Infection, Case Importation and Personal Contacts

2020

Preprint

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“…7). The estimation of Rt has been discussed extensively in the literature, and tools are also provided(8) (22)(23)(24)(25). Websites such as https://rt.live/ also provide the real-time estimation of the Rt for all 50 states of the US.…”

Section: Discussion On Implementationsmentioning

confidence: 99%

A Model for the Testing and Tracing Needed to Suppress COVID-19

Wang¹

2020

Preprint

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This paper presents a simple mathematical model that answers how much testing and tracing we need to do to suppress new surges of COVID-19 infections after reopening. We derived the model by modifying the SEIR model taking into the effects of testing and tracing. The following equation is one of the essential outcomes of the model: ρ>(R0S/N-1)/(D(1+ηR0)) Where ρ is the percentage of infectious people that have to be detected per day, R0 is the basic reproduction number, S/N is the percentage of the susceptible population over the entire population, D is the length of the infectious period, and η is the percentage of close contacts that have to be traced. If the above equation is satisfied, we can bring the effective reproduction number Re to below 1 to get the transmission suppressed. This model demonstrates that together with social-distancing measures such as wearing masks in public, with a reasonable amount of testing and tracing, we may suppress the COVID-19 transmission for good. For example, if social distancing measures can bring R0 to below 1.2, for D being 10 days, in places where 15% people have developed antibodies, we can suppress the transmission by detecting only 0.13% of the infectious population daily while tracing 50% of their close contacts. The model provides intuitive insights and quantitative guidance for policymakers and public health practitioners to deploy the testing and tracing resources optimally.

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“…[18] Therefore, for these numbers a range of 50-67% of the population must be resistant so that herd immunity acquirement would drop the infection rates. [19] A graphical outline of how the herd immunity can stop an infectious disease spread is presented in Figure 1. Vaccination is a way to stop infectious diseases and this endeavor to build herd immunity was verified in many other infectious diseases.…”

Section: Herd Immunity Outlinesmentioning

confidence: 99%

The bumpy road to achieve herd immunity in COVID-19

Neagu

2020

Journal of Immunoassay and Immunochemistry

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Herd immunity is a form of indirect protection that is offered to the community when a large proportion of individuals contained in the community are immune to a certain infection. This immunity can be due to vaccination or to the recovery postdisease. Effective herd immunity in SARS-CoV-2 infection has several hurdles upon achievement. Herd immunity cannot be obtained concomitantly in many geographical areas because the areas have different population density and the societal measures to contain the spreading are different. A proportion of 50-66% of the population needs to be immunized naturally or artificially in this SARS-Cov2 pandemic and this percentage is not easily achievable. The duration of herd immunity is another issue while information on the long-term immune response against SARS-CoV2 is yet scarce. Epitope stability, another issue to be solved when achieving herd immunity, is important. Mutation in the viral structure will call upon other sets of neutralizing antibodies and hence for other herd immunity type installment. The societal tactics to achieve the much-needed herd immunity should be developed keeping in mind the welfare of the population. Without being exhaustive, throughout our paper we will elaborate on each of the hurdles encountered in developing herd immunity to SARS-Cov2 infection.

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Serial interval in determining the estimation of reproduction number of the novel coronavirus disease (COVID-19) during the early outbreak

Cited by 50 publications

References 6 publications

Modeling Return of the Epidemic: Impact of Population Structure, Asymptomatic Infection, Case Importation and Personal Contacts

Modeling Return of the Epidemic: Impact of Population Structure, Asymptomatic Infection, Case Importation and Personal Contacts

A Model for the Testing and Tracing Needed to Suppress COVID-19

The bumpy road to achieve herd immunity in COVID-19

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