SARS incubation and quarantine times: when is an exposed individual known to be disease free?

Farewell, Vernon T.; Herzberg, Agnes M.; James, Karl; Ho, Lai‐Ming; Leung, Gabriel M.

doi:10.1002/sim.2206

Cited by 35 publications

(38 citation statements)

References 9 publications

(10 reference statements)

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“…10,11 In a subset of cases, information was available on dates of exposure to infection, and in the majority of cases this was recorded as intervals of 2 or more days during which infection may have occurred rather than exact dates of infection. 2,6,7,10 We also analysed a separate subset of cases who were residents of the Amoy Gardens housing estate where a potential super-spreading event occurred in March 2003. 12–14 For these patients, we removed the small proportion of cases with onset dates prior to the main outbreak and with onset dates >14 days after the start of the main outbreak (eAppendix).…”

Section: Methodsmentioning

confidence: 99%

“…First, we used a non-parametric estimator of the survival function that is a generalization of the Kaplan-Meier estimator for interval-censored data. 16 Second, we fitted a lognormal distribution 1,6,7,17 allowing for interval censoring, estimating the location and scale parameters (μ and σ) using Markov Chain Monte Carlo (MCMC) in a Bayesian framework.…”

Section: Methodsmentioning

confidence: 99%

“…3–6 Estimation of the incubation period of a pathogen such as the SARS coronavirus can be complicated because infection events cannot be directly observed and exposure data are consequently interval-censored. 7 …”

Section: Introductionmentioning

confidence: 99%

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Brief Report

Virlogeux¹,

Fang

et al. 2015

Epidemiology

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Background Few previous studies have investigated the association between the severity of an infectious disease and the length of incubation period. Methods We estimated the association between the length of the incubation period and the severity of infection with the severe acute respiratory syndrome (SARS) coronavirus, using data from the epidemic in 2003 in Hong Kong. Results We estimated the incubation period of SARS based on a subset of patients with available data on exposure periods and a separate subset of patients in a putative common source outbreak, and we found significant associations between shorter incubation period and greater severity in both groups after adjusting for potential confounders. Conclusions Our findings suggest that patients with a shorter incubation period proceeded to have more severe disease. Further studies are needed to investigate potential biological mechanisms for this association.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Brief Report

Virlogeux¹,

Fang

et al. 2015

Epidemiology

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show abstract

“…This condition should be reasonable here in the setting of H7N9, with each exposure interval being relatively short. Moreover, in order to allow for the coarseness of expo-sure data reported on a daily basis, we added 0.5 to each upper bound and subtracted 0.5 from each lower bound (13).…”

Section: Statistical Analysesmentioning

confidence: 99%

“…The most basic approach to dealing with interval-exposure data is to impute the infection date as the midpoint of any exposure interval, which then permits empirical estimation (13). However, this approach may lead to overestimation of the incubation period distribution, which tends to be right-skewed (14).…”

Section: Statistical Analysesmentioning

confidence: 99%

Estimating the Distribution of the Incubation Periods of Human Avian Influenza A(H7N9) Virus Infections

Virlogeux¹,

Li²,

Tsang³

et al. 2015

Am. J. Epidemiol.

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A novel avian influenza virus, influenza A(H7N9), emerged in China in early 2013 and caused severe disease in humans, with infections occurring most frequently after recent exposure to live poultry. The distribution of A(H7N9) incubation periods is of interest to epidemiologists and public health officials, but estimation of the distribution is complicated by interval censoring of exposures. Imputation of the midpoint of intervals was used in some early studies, resulting in estimated mean incubation times of approximately 5 days. In this study, we estimated the incubation period distribution of human influenza A(H7N9) infections using exposure data available for 229 patients with laboratory-confirmed A(H7N9) infection from mainland China. A nonparametric model (Turnbull) and several parametric models accounting for the interval censoring in some exposures were fitted to the data. For the best-fitting parametric model (Weibull), the mean incubation period was 3.4 days (95% confidence interval: 3.0, 3.7) and the variance was 2.9 days; results were very similar for the nonparametric Turnbull estimate. Under the Weibull model, the 95th percentile of the incubation period distribution was 6.5 days (95% confidence interval: 5.9, 7.1). The midpoint approximation for interval-censored exposures led to overestimation of the mean incubation period. Public health observation of potentially exposed persons for 7 days after exposure would be appropriate.

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Incubation Period of Infectious Diseases

Brookmeyer

2015

Wiley StatsRef: Statistics Reference Online

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The incubation period of an infectious disease is the time interval between the exposure to a disease‐causing infectious agent and the onset of symptomatic (clinical) disease. The incubation period of a disease can be very variable among individuals and a single number, such as the mean or median incubation period, does not reveal the significant heterogeneity in incubation periods in a population. Estimating the distribution of incubation periods is important for a multitude of reasons including modeling the current and future scope of epidemics and evaluating disease control strategies. Important statistical issues arise in estimating incubation period distributions because of incomplete data and selection biases in epidemiological studies. Statistical methods for censored and truncated data are important for addressing those issues in the analyses of incubation periods. Syntheses of data from multiple studies of incubation periods can help overcome the limitations of any single study.

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SARS incubation and quarantine times: when is an exposed individual known to be disease free?

Cited by 35 publications

References 9 publications

Brief Report

Brief Report

Estimating the Distribution of the Incubation Periods of Human Avian Influenza A(H7N9) Virus Infections

Incubation Period of Infectious Diseases

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