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Table 1 Characteristics of included studies and summary of result

From: Global strategies and effectiveness for COVID-19 prevention through contact tracing, screening, quarantine, and isolation: a systematic review

S.N Study characteristics and summary report
1 Author/s and title [14] Matt J Keeling, T Déirdre Hollingsworth, Jonathan M Read. The efficacy of contact tracing for the containment of the 2019 novel coronavirus (COVID-19).
Population size (N) 5802
Country UK
Setting Community based
Design Cross-sectional study
Objectives To investigate the efficacy of contact tracing for the containment of Covid-19
Study detail Contact patterns was characterized using a postal and online cross-sectional survey
Interventions Contact tracing
Results Assuming that all the contact tracing can be performed rapidly, contact tracing to reduce the basic reproductive ratio from 3.11 to 0.21, enabling the outbreak to be contained. Each new case requires an average of 36 individuals to be traced, with 8.7% of cases having more than 100 close traceable contacts.
2 Author/s and title [15] Zengyun Hu, Qianqian Cui, Junmei Han. Evaluation and prediction of the COVID-19 variations at different input population and quarantine strategies, a case study in Guangdong province, China
Population size (N) 113460000
Country China
Setting Community based
Design Case study
Objectives To simulate and predict the disease variations of Guangdong province and to explore the impacts of the input population and quarantine strategies.
Study detail The impact of input population was evaluated with simulation
Interventions Quarantine
Results ➢ The simulated peak value of the confirmed cases is 1002 at Feb 10, 2020
➢ The disease will become extinction with peak value of 1397 at May 11, 2020.
➢ The increased numbers of the input population can mainly shorten the disease extinction days and the increased percentages of the exposed individuals
3 Author/s and title [16] Mingwang S, Zhihang P, Yuming Gu, et al. Assessing the effects of metropolitan-wide quarantine on the spread of COVID-19 in public space and households
Population size (N) All population in Hubei province, China
Country China
Setting Community based
Design Retrospective
Objectives To evaluate the impact of the metropolitan-wide quarantine on the trend and transmission route of the SARS-CoV-2 epidemic
Study detail Data was collected on the number of cumulative confirmed cases
Interventions Quarantine
Results In the presence of the quarantine, 100,610 infections, 68,975 confirmed cases and 3252 deaths would have occurred
Quarantine would prevent 79.27% of deaths, 87.08% and 71.84% of infections in public space and households, respectively.
4 Author/s and title [17] Jean C, Philippe C, et al. Testing the repatriated for SARS-Cov2: should laboratory-based quarantine replace traditional quarantine?
Population size (N) 337
Country France
Setting Community based
Design Cross-sectional
Objectives To test all passengers for SARS-Cov2 twice in order to reduce anxiety among the population and decision makers
Study detail The presence of SARS-CoV-19 in asymptomatic carriers were investigated by testing all repatriated patients within the first 24 h of their arrival in France and at day 5, n = 337
Interventions Laboratory-based quarantine
Results 337 passengers were tested at day 0 and day 5.
Reducing the time scale to a matter of hours with molecular diagnosis is important
5 Author/s and title [18] Hao-Yuan et al. Contact tracing assessment of COVID-19 transmission dynamics in Taiwan and risk at different exposure periods before and after symptom onset
Population size (N) 100
Country Taiwan
Setting Community, health care setting
Design Prospective case-ascertained study
Objectives To delineate the transmission dynamics of COVID-19 and evaluate the transmission risk at different exposure window periods before and after symptom onset.
Study detail Prospective case-ascertained study that enrolled all the initial 100 confirmed cases
Interventions Contact tracing, all contacts were followed up until 14 days
Results The overall secondary clinical attack rate was 0.7% (95% CI, 0.4–1.0%).
The attack rate was higher among the 1818 contacts whose exposure to index cases started within 5 days of symptom onset.
The 299 contacts with exclusive presymptomatic exposures were also at risk
High transmissibility of COVID-19 before and immediately after symptom
6 Author/s and title [19] Guan Wang, Wenhu Chen, Xian Jin, Yi-Peng Chen. Description of COVID-19 cases along with the measures taken on prevention and control in Zhejiang, China
Population size (N) Population in Hangzhou, Wenzhou, Ningbo, and Taizhou of Zhejiang Province
Country China
Setting Community based
Design Retrospective study
Objectives To perform a descriptive analysis of clinical characteristics and epidemiological factors of COVID-19 patients and summed up the steps for disease control and treatment in Zhejiang province.
Study detail Clinical characteristics were carried out on 889 confirmed cases
Interventions Screening, masks use, prohibiting public gathering, and suspending public transportation
Results ➢ The factor of intimate contact with confirmed cases took up for 39%, 39%, 64%, and 44% in Hangzhou, Wenzhou, Ningbo, and Taizhou, respectively, which was the leading cause of COVID-19.
➢ Preventing contact with confirmed cases could largely avoid the disease to happen.
7 Author/s and title [20] Siukan Law, et al. Severe acute respiratory syndrome (SARS) and coronavirus disease-2019 (COVID-19): from causes to preventions in Hong Kong
Population size (N) General population in Hong Kong
Country Hong Kong
Setting Community based
Design Retrospective
Objectives To discuss the current understanding of COVID-19 and compares with the outbreak of SARS-CoV-2 in 2003 of Hong Kong
Study detail A retrospective study was performed to summarize the current knowledge of COVID-19
Interventions Cases and contact handling and prevention activities on healthcare workers and community
Results Personal hygiene and protection are the most important for preventing the spread of COVID-19 such as wearing a mask and washing hands as well as reducing social contact including avoiding crowds and working at home.
8 Author/s and title [21] Vincent C. et al. Escalating infection control response to the rapidly evolving epidemiology of the coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 in Hong Kong
Population size (N) Population in Hong Kong
Country Hong Kong
Setting Health care setting
Design Case-control study, HCWs with unprotected exposure
Objectives To describe the infection control preparedness measures undertaken for coronavirus disease (COVID-19)
Study detail A bundled approach of active and enhanced laboratory surveillance, early airborne infection isolation, rapid molecular diagnostic testing, and contact tracing for healthcare workers (HCWs) with unprotected exposure in the hospitals was implemented
Interventions Isolation, rapid molecular diagnostic testing, and contact tracing
Results Vigilance in hand hygiene practice, wearing of surgical masks in the hospital, and appropriate use of PPE in patient care are the key infection control measures
9 Author/s and title [22] Yansen Bai; et al. SARS-CoV-2 infection in health care workers: a retrospective analysis and model study
Population size (N) HCWs in the department of neurosurgery of union hospital of Wuhan, N = 171
Country China
Setting Health care setting
Design Single center of case-control series
Objectives ➢ To investigate the risk factors to COVID-19.
Study detail A single-center study was carried out in the Department of Neurosurgery,
Interventions Quarantine and isolation
Results By reducing the average contact rate per HCW by a 1.35 factor and susceptibility by a 1.40 factor, we can avoid an outbreak of the basic case among HCWs.
10 Author/s and title [23] Xiuli L. et al. Modelling the situation of COVID-19 and effects of different containment strategies in China with dynamic differential equations and parameters estimation
Population size (N) General population in china
Country China
Setting Community based
Design QSEIR modeling
Objectives To estimate the dynamic evolution mechanism of the epidemic in China, to find when the epidemic will end and how this result depends on different containment strategies.
Study detail A quantitative prediction of future epidemic developments based on different containment strategies with the QSEIR model has been made by setting January 23, 2020, as the beginning date of the simulation (5000)
Interventions Quarantine
Results Quarantine measures are the most effective containment strategy to control the epidemic.
11 Author/s and title [24] Adam J. et al. Effectiveness of isolation, testing, contact tracing and physical distancing on reducing transmission of SARS-CoV-2 in different settings: modelling study
Population size (N) General population in UK
Country UK
Setting Community based
Design Mathematical modeling
Objectives To understand what combination of measures including novel digital tracing approaches and less intensive physical distancing may be required to reduce transmission.
Study detail Using a model of individual-level transmission stratified by setting (household, work, school, other) based on BBC Pandemic data from 40,162 UK participants
Interventions Isolation, testing, contact tracing, and physical distancing
Results ➢ Combined isolation and tracing strategies would reduce transmission more than mass testing or self-isolation alone (50–60% compared to 2–30%).
12 Author/s and title [25] Biao Tang, et al. Estimation of the transmission risk of the 2019-nCoV and its implication for public health interventions
Population size (N) Population in China
Country China
Setting Community based, health care
Design Mathematical Modeling, R0 = 6.47
Objectives To estimate the basic reproduction number by means of mathematical modeling
Study detail A deterministic compartmental model was devised based on the clinical progression of the disease, epidemiological status of the individuals, and intervention measures.
Interventions Contact tracing, quarantine and isolation
Results ➢ The estimations based on likelihood and model analysis show that the control reproduction number may be as high as 6.47 (95% CI, 5.71–7.23).
➢ Interventions, such as intensive contact tracing followed by quarantine and isolation, can effectively reduce the control reproduction number
➢ With travel restriction, the number of infected individuals in seven days will decrease by 91.14% in Beijing, compared with the scenario of no travel restriction.
13 Author/s and title [26] Rocklöv J, et al. COVID-19 outbreak on the Diamond Princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures
Population size (N) Population in cruise ship
Country Japan
Setting Community based
Design SEIR modeling
Objectives To study the empirical data of COVID-19 confirmed infections on the Cruise ship Diamond Princess, to estimate the R0.
Study detail SEIR modeling was used on data confirmed cases on the cruise ship
Interventions Isolation, quarantine, and removal interventions
Results ➢ Based on the modeled initial of 14.8, without any interventions within period of 21 January to 19 February, 2020, out of the 3700 (79%) would have been infected.
➢ The R0 was 14.8 initially and then declined to a stable 1.78 after the quarantine, and removal interventions were initiated.
➢ Isolation and quarantine therefore prevented 2307 cases
14 Author/s and title [27] Zhao S, Chen H. Modeling the epidemic dynamics and control of COVID-19 outbreak in China
Population size (N) Population in china (excluding Hubei)
Country China
Setting Community based
Design Mathematical modeling, SUQC
Objectives To characterize the dynamics of COVID-19
Study detail SUQC model is applied to the daily released data
Interventions Quarantine
Results ➢ The confirmation rate of Wuhan is 0.0643, substantially lower than that of Hubei excluding Wuhan (0.1914) and that of China excluding Hubei (0.2189), but it jumps to 0.3229 after February 12 when clinical evidence was adopted
➢ The number of unquarantined infected cases in Wuhan on February 12, 2020, is estimated to be 3509 and declines to 334 on February 21, 2020.
15 Author/s and title [28] Neil M et al. Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand
Population size (N) Population in the UK and USA
Country UK and USA
Setting Community based
Design Mathematical modeling study
Objectives To assess the potential role of a number of public health measures—so-called non-pharmaceutical interventions (NPIs)
Study detail The effect of non-pharmacological measures were measured
Interventions Non-pharmaceutical interventions
Results ➢ To reduce R0 to close to 1 or below, a combination of case isolation, social distancing, quarantine, or school and university closure are required
➢ Optimal mitigation policies reduce healthcare demand by 2/3 and deaths by half.
16 Author/s and title [29] Zifeng Yang, et al. Modified SEIR and AI prediction of the epidemics trend of COVID-19 in China under public health interventions
Population size (N) Population in china
Country China
Setting Community based
Design Mathematical Modeling, SEIR and an artificial intelligence (AI) approach
Objectives A modified susceptible-exposed-infected-removed (SEIR) epidemiological model was used that incorporates the domestic migration data before and after January 23 and the most recent COVID-19 epidemiological data to predict the epidemic progression.
Study detail SEIR model was used epidemiological data based on daily COVID-19 outbreak numbers reported by the National Health Commission of China
Interventions Quarantine, strict controls on travel and extensive monitoring of suspected cases
Results ➢ A 5-day delay in implementation would have increased epidemic size three-fold.
➢ Where the interventions to be introduced 5 days earlier than they had been, the number of cases nationwide would have been 40,991
➢ Lifting the Hubei quarantine would lead to a second epidemic peak in Hubei province in mid-March and extend the epidemic to late April
17 Author/s and title [30] Peak, Corey M., et al. Modeling the comparative impact of individual quarantine vs. active monitoring of contacts for the mitigation of COVID-19 (2020)
Population size (N) 2000
Country USA
Setting General population
Design Stochastic branching model
Objectives To estimate the comparative efficacy of these interventions to control COVID-19 using a stochastic branching model
Study detail A branching model was fitted for comparing two sets of reported parameters for the dynamics of the disease with a mean serial interval of 4.8 days and 7.5 days
Interventions Individual quarantine vs. active monitoring of contacts
Results ➢ If social distancing reduces the reproductive number to 1.25 (e.g., 50% of person-to-person contact is removed in a setting where R0 = 2.5), active monitoring of 50% of contacts can result in overall outbreak control (i.e., Re < 1).
➢ Tracing 10%, 50%, or 90% of contacts on top of social distancing resulted in a median reduction in Re of 3.2%, 15%, and 33%, respectively, for active monitoring and 5.8%, 32%, and 66%, for individual quarantine.
➢ Individual quarantine may contain an outbreak of COVID-19 with a short serial interval (4.8 days) only in settings with high intervention performance where at least three-quarters of infected contacts are individually quarantined.
18 Author/s and title [31] Biao Tang et al. The effectiveness of quarantine and isolation determine the trend of the COVID-19 epidemics in the final phase of the current outbreak in China
Population size (N) General population in china
Country China
Setting Community based
Design dynamic model
Objectives To devise a dynamic model with suspected compartment incorporating prevention and control strategies to predict the trend of the COVID-19 epidemics based on multiple data sources and assess the efficacy of control strategies
Study detail data of laboratory-confirmed COVID-19 cases in China was obtained from the “National Health Commission” of the People’s Republic of China and the Hubei’s “Health Commission
Interventions Quarantine and isolation
Results The trend of the epidemics mainly depends on quarantined and suspected cases.
Most infected cases have been quarantined or put in suspected class, which has been ignored in existing models.
The strong measures implemented have reduced the effective reproduction number. These interventions may take a longer time to be effective as the second and third generations of infected people are exposed in succession.
19 Author/s and title [32] Can Hou, et al. The effectiveness of quarantine of Wuhan city against the corona virus disease 2019 (COVID-19): A well-mixed SEIR model analysis
Population size (N) 11081000
Country China
Setting Community based
Design A well-mixed SEIR modeling
Objectives to explore the effectiveness of the quarantine of Wuhan city against the epidemic
Study detail The data of confirmed and suspected cases of COVID-19 acute respiratory disease reported by cities and provinces in mainland China were obtained
Interventions Quarantine
Results Reducing the contact rate of latent individuals after quarantine and isolation can effectively reduce the number of individuals infected with COVID-19 and delay the peak time.
20 Author/s and title [33] Joel Hellewell, et al. Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts
Population size (N) 100
Country UK
Setting Community based
Design Stochastic transmission modeling
Objectives To assess if isolation and contact tracing are able to control onwards transmission from imported cases of COVID-19
Study detail A mathematical model was employed to assess the feasibility of contact tracing and case isolation to control outbreaks of using simulated new outbreaks starting from 5, 20, or 40 introduced cases.
Interventions Contact tracing and case isolation
Results When R0 was 2.5 or 3.5, the probability of controlling an outbreak decreased with the number of initial cases
The majority of scenarios with an R0 of 1.5 were controllable with less than 50% of contacts successfully traced.
To control the majority of outbreaks, for R0 of 2.5, more than 70% of contacts had to be traced, and for an R0 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 R0 was 1.5.
For R0 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.
Contact tracing and isolation might not contain outbreaks of COVID-19 unless very high levels of contact tracing are achieved.
21 Author/s and title [34] Katelyn Gostic, et al. Estimated effectiveness of symptom and risk screening to prevent the spread of COVID-19.
Population size (N) 30
Country USA
Setting Community based
Design Mathematical modeling
Objectives To estimate the impact of different screening programs given current knowledge of key COVID-19 life history and epidemiological parameters
Study detail  
Interventions Screening
Results In a growing epidemic, even under the best-case assumptions, with just one infection in twenty being subclinical and all travelers passing through departure and arrival screening, the median fraction of infected travelers detected is only 0.30
In a stable epidemic, under the middle-case assumption that 25% of cases are subclinical, it is estimated that arrival screening alone would detect roughly one-third of infected travelers and that a combination of arrival and departure screening would detect nearly half of infected travelers
Under best-case assumptions, screening will miss more than half of infected people
22 Author/s and title [35] Mirjam E. et al. Isolation and contact tracing can tip the scale to containment of COVID-19 in populations with social distancing
Population size (N) 100
Country Netherlands
Setting Community based
Design stochastic transmission model
Objectives To evaluate under which conditions containment could be achieved with combinations of social distancing, isolation and contact tracing
Study detail Stochastic transmission model-based analyses of the impact of isolation and contact tracing in a setting with various levels of social distancing measures, using varying levels of the effectiveness and timeliness of contact tracing was provided, n = 100.
Interventions Isolation and contact tracing in populations with social distancing
Results If the proportion of asymptomatic infections is larger than 30%, contact tracing and isolation cannot achieve containment for an R0 of 2.5
To achieve containment by social distancing requires a reduction of numbers of non-household contacts by around 90%.
Social distancing reduces non-household contacts only by 50%, tracing and isolation also of non-household contacts is needed for containment.