Contact Tracing for Imported Case of Middle East Respiratory Syndrome, China, 2015

Kang, Min; Song, Tie; Zhong, Huan; Hou, Jie; Wang, Jun; Li, Jiansen; Wu, Jie; He, Jianfeng; Lin, Junfen; Zhang, Yonghhui

doi:10.3201/eid2209.152116

Cited by 38 publications

(35 citation statements)

References 10 publications

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“…In the 2014 Ebola epidemic in Liberia, each case reported between six and 20 contacts, 8 and the number of contacts seen in MERS outbreaks is often higher than that. 10 20 contacts for each of 100 cases means 2000 contacts traced to achieve control. Uncontrolled outbreaks typically had higher numbers of cases (appendix p 13).…”

Section: Resultsmentioning

confidence: 99%

Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts

Hellewell

Abbott

Gimma

et al. 2020

The Lancet Global Health

2,442

2,403

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Background Isolation of cases and contact tracing is used to control outbreaks of infectious diseases, and has been used for coronavirus disease 2019 (COVID-19). Whether this strategy will achieve control depends on characteristics of both the pathogen and the response. Here we use a mathematical model to assess if isolation and contact tracing are able to control onwards transmission from imported cases of COVID-19. MethodsWe developed a stochastic transmission model, parameterised to the COVID-19 outbreak. We used the model to quantify the potential effectiveness of contact tracing and isolation of cases at controlling a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-like pathogen. We considered scenarios that varied in the number of initial cases, the basic reproduction number (R 0 ), the delay from symptom onset to isolation, the probability that contacts were traced, the proportion of transmission that occurred before symptom onset, and the proportion of subclinical infections. We assumed isolation prevented all further transmission in the model. Outbreaks were deemed controlled if transmission ended within 12 weeks or before 5000 cases in total. We measured the success of controlling outbreaks using isolation and contact tracing, and quantified the weekly maximum number of cases traced to measure feasibility of public health effort.Findings Simulated outbreaks starting with five initial cases, an R 0 of 1·5, and 0% transmission before symptom onset could be controlled even with low contact tracing probability; however, the probability of controlling an outbreak decreased with the number of initial cases, when R 0 was 2·5 or 3·5 and with more transmission before symptom onset. Across different initial numbers of cases, the majority of scenarios with an R 0 of 1·5 were controllable with less than 50% of contacts successfully traced. To control the majority of outbreaks, for R 0 of 2·5 more than 70% of contacts had to be traced, and for an R 0 of 3·5 more than 90% of contacts had to be traced. The delay between symptom onset and isolation had the largest role in determining whether an outbreak was controllable when R 0 was 1·5. For R 0 values of 2·5 or 3·5, if there were 40 initial cases, contact tracing and isolation were only potentially feasible when less than 1% of transmission occurred before symptom onset.Interpretation In most scenarios, highly effective contact tracing and case isolation is enough to control a new outbreak of COVID-19 within 3 months. The probability of control decreases with long delays from symptom onset to isolation, fewer cases ascertained by contact tracing, and increasing transmission before symptoms. This model can be modified to reflect updated transmission characteristics and more specific definitions of outbreak control to assess the potential success of local response efforts.

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Section: Resultsmentioning

confidence: 99%

Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts

Hellewell

Abbott

Gimma

et al. 2020

The Lancet Global Health

2,442

2,403

View full text Add to dashboard Cite

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“…The main objectives of contact tracing are to identify potentially infected individuals before the onset of severe symptoms, and to prevent onward transmission from the secondary cases. Contact tracing has decisively contributed to the control of many infectious diseases worldwide including severe acute respiratory syndrome (SARS), Ebola virus disease, and Middle East respiratory syndrome (MERS) [4][5][6][7]. Report of the WHO-China Joint Mission on COVID-19 pointed out that China has a policy of meticulous case and contact identification for COVID-19 [8].…”

Section: Introductionmentioning

confidence: 99%

Risk factors associated with COVID-19 infection: a retrospective cohort study based on contacts tracing

Liu

Liang

Zhong

et al. 2020

Emerging Microbes & Infections

Self Cite

126

166

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This study aimed to estimate the attack rates, and identify the risk factors of COVID-19 infection. Based on a retrospective cohort study, we investigated 11,580 contacts of COVID-19 cases in Guangdong Province from 10 January to 15 March 2020. All contacts were tested by RT-PCR to detect their infection of SARS-COV-2. Attack rates by characteristics were calculated. Logistic regression was used to estimate the risk factors of infection for COVID-19. A total of 515 of 11,580 contacts were identified to be infected with SARS-COV-2. Compared to young adults aged 20-29 years, the infected risk was higher in children (RR: 2.59, 95%CI: 1.79-3.76), and old people aged 60-69 years (RR: 5.29, 95%CI: 3.76-7.46). Females also had higher infected risk (RR: 1.66, 95%CI: 1.39-2.00). People having close relationship with index cases encountered higher infected risk (

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“…With the assumptions outlined above, for England and Wales as a whole the network model assumes that typically between 30 and 40% of transmission events are intra-community, with dense urban communities exhibiting the lowest levels of intracommunity transmission (ie., those communities are more mixed 8 ) and rural communities the highest. For transmission that occurs in the community and in the workplace, the intra-community transmission constitutes 10 − 20%, while in schools intra-community transmission accounts for ∼20-40% of the total.…”

Section: Discussion and Caveatsmentioning

confidence: 98%

Containing Covid-19 outbreaks with spatially targeted short-term lockdowns and mass-testing

Alsing

2020

Preprint

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We assess the efficacy of spatially targeted lockdown or mass-testing and case-isolation in individual communities, as a complement to contact-tracing and social-distancing, for containing SARS-CoV-2 outbreaks. Using the UK as a case study, we construct a stochastic branching process model for the virus transmission, embedded on a network interaction model encoding mobility patterns in the UK. The network model is based on commuter data from the 2011 census, a catchment area model for schools, and a phenomenological model for mobility and interactions outside of work, school, and the home. We show that for outbreak scenarios where contact-tracing and moderate social distancing alone provide suppression but do not contain the spread, targeted lockdowns or mass-testing interventions at the level of individual communities (with just a few thousand inhabitants) can be effective at containing outbreaks. For spatially targeted mass-testing, a moderate increase in testing capacity would be required (typically < 40000 additional tests per day), while for local lockdowns we find that only a small fraction (typically < 0.1%) of the population needs to be locked down at any one time (assuming that one third of transmission occurs in the home, at work or school, and out in the wider community respectively). The efficacy of spatially targeted interventions is contingent on an appreciable fraction of transmission events occurring within (relative to across) communities. Confirming the efficacy of community-level interventions therefore calls for detailed investigation of spatial transmission patterns for SARS-CoV-2, accounting for sub-community-scale transmission dynamics, and changes in mobility patterns due to the presence of other containment measures (such as social distancing and travel restrictions).Disclaimer: We stress that this is a working paper where results are preliminary and subject to change. In particular, we note that the efficacy of spatially targeted interventions are sensitive to the relative proportions of intra-versus inter-community transmission (for a given definition of community boundaries), which in turn is sensitive to the assumptions about the transmission dynamics across different contexts. Whilst the assumptions made here about transmission across contexts are motivated, we are currently updating our model to make the estimated inter-and intra-community transmission rates as robust as possible, as well as running a comprehensive suite of sensitivity tests and different outbreak scenarios.

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Contact Tracing for Imported Case of Middle East Respiratory Syndrome, China, 2015

Cited by 38 publications

References 10 publications

Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts

Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts

Risk factors associated with COVID-19 infection: a retrospective cohort study based on contacts tracing

Containing Covid-19 outbreaks with spatially targeted short-term lockdowns and mass-testing

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