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By achieving capacity to conduct 200,000 tests for COVID-19 per day and employing 25,000 individuals to do contact tracing, the UK is in a strong position to “go after the virus,” as Dr Mike Ryan has put it. However, the system will need to operate at the quality and capacity that is needed.
WHO surveillance statistics (1) suggest that both rapid case diagnosis and contact tracing are important for COVID-19 containment. The experiences of Hubei province in China and many other countries show that just diagnosing and managing unwell cases leads to disaster. However, data from provinces in China outside of Hubei and from South Korea show that large outbreaks can actually be brought under control (2). China and other successful countries such as South Korea, Taiwan, Singapore, Australia and Iceland, have had Rapid Case Contact Management as the central component of their response. They have had different approaches to border control, school closures, the use of face masks, and social distancing. Rapid Case Contact Management was described by Drs Aylward and Liang as comprising 90% of the Chinese national response (3). Its efficacy may increase when enhanced electronically (4) and if it is operating within a context of general social distancing measures.
Two key properties of SARS-CoV-2 also suggest that both rapid case diagnosis and contact tracing are important. Firstly, SARS-CoV-2 has peak transmissibility very early after the development of symptoms (5), whereas the SARS-CoV-1 did not reach peak transmissibility for at least 6 days after symptoms developed. This means that a strategy limited to just diagnosing cases leaves it too late to stop ongoing SARS-CoV-2 transmission. Secondly, SARS-CoV-2 has a mean incubation period of 5-6 days (6), whereas H1N1 influenza virus tends to cause disease within 2-3 days. This means that there is more time to find all the contacts of a COVID-19 case and place them in quarantine. However, clearly a high proportion of cases must be diagnosed and isolated early in their illness, and contacts must be identified and quarantined rapidly.
Rapid Case Contact Management does not need to be perfect, but it needs to operate at high quality across the system, even in the presence of large numbers of COVID-19 cases. We have developed a framework to optimise the quality of tuberculosis case contact management thatcan be adapted for COVID-19 (7). Simple epidemiological tools are applied to gather data related to performance indicators (8). Performance failure is then analysed and options assessed for closing the gaps that are identified. We propose 10 system performance indicators for the COVID-19 Rapid Case Contact Management system, along with proposed target measurements, below. The target measurements have been created on the basis of the following principles. Firstly, contacts should be placed in quarantine before the average incubation period of the virus, and for a duration 14 days since their last exposure. Secondly, pragmatically, some activities require more person-time to complete than others do. Finally, modelling suggests that over 80% of contacts need to be promptly traced and quarantined for an outbreak to be controlled (9). Of note, in a high performing system, contact tracing reduces the average time from the development of symptoms to testing in cases.
If the UK can diagnose a high proportion of COVID-19 cases quickly and quarantine their contacts rapidly and effectively, with augmentation by other measures (especially electronic enhancement and social distancing), this could be the key to protecting the population until an effective vaccine and/or therapeutics are available.
Ten performance indicators and their targets for Rapid Case Contact Management of COVID-19:
1. Number of cases able to have contact tracing completed/day
Rationale: Ensures adequate capacity to conduct quality rapid case contact management
Target: At least 200 cases/million population and their contacts within 5 days
2. Percentage of prospective cases who should have a test, who have a test done
Rationale: A high proportion of cases need to be detected
Target: >90%
3. Time from prospective case symptom onset to test
Rationale: Late detection delays case isolation and potentially increases number of contacts
Target: <2 days in >80%
4. Time from prospective case sampling to test result
Rationale: Slow turn-around times delay case isolation and contact tracing
Target: <24 hours in >80%
5. Time from PHU notification of case to contact identification
Rationale: Delayed notification case isolation compromises effectiveness of contact tracing
Target: <12 hours in >80%
6. Percentage of identified contacts who are traced, stratified by household or close contact
Rationale: Failure to complete contact tracing increases the likelihood of onwards transmission
Target: >80%
7. Time from contact identification to isolation
Rationale: Timely contact tracing prevents onwards transmission
Target: <24 hours in >80%
8. Percentage of contacts quarantined within 3 days of symptom onset of index case
Rationale: Contacts should be quarantined within the incubation period of the virus
Target: >80%
9. Percentage of contacts adhering to quarantine
Rationale: Poor adherence risks onwards transmission of the virus
Target: >90%
10. Percentage of contacts of SARS-CoV-2 positive contacts who become SARS-CoV-2 positive
Rationale: This is a sign of failed contact tracing or of failed quarantine
Target: <1%
References
1. World Health Organisation. Coronavirus disease (COVID-19) situation reports: World Health Organisation; 2020 [cited 2020 2 May]. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situatio....
2. Covid-19 National Emergency Response Center E, Case Management Team KCfDC, Prevention. Coronavirus Disease-19: The First 7,755 Cases in the Republic of Korea. Osong Public Health Res Perspect. 2020;11(2):85-90.
3. World Health Organisation. Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). Geneva: World Health Organisation; 2020 28/02/2020.
4. Ferretti L, Wymant C, Kendall M, Zhao L, Nurtay A, Abeler-Dorner L, et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science. 2020.
5. Wang Y, Wang Y, Chen Y, Qin Q. Unique epidemiological and clinical features of the emerging 2019 novel coronavirus pneumonia (COVID-19) implicate special control measures. J Med Virol. 2020.
6. Zhang J, Litvinova M, Wang W, Wang Y, Deng X, Chen X, et al. Evolving epidemiology and transmission dynamics of coronavirus disease 2019 outside Hubei province, China: a descriptive and modelling study. Lancet Infect Dis. 2020.
7. Hill PC, Rutherford ME, Audas R, van Crevel R, Graham SM. Closing the policy-practice gap in the management of child contacts of tuberculosis cases in developing countries. PLoS medicine. 2011;8(10):e1001105.
8. Rutherford ME, Ruslami R, Anselmo M, Alisjahbana B, Yulianti N, Sampurno H, et al. Management of children exposed to Mycobacterium tuberculosis: a public health evaluation in West Java, Indonesia. Bull World Health Organ. 2013;91(12):932-41A.
9. Hellewell J, Abbott S, Gimma A, Bosse NI, Jarvis CI, Russell TW, et al. Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts. Lancet Glob Health. 2020;8(4):e488-e96.
Competing interests:
No competing interests
31 May 2020
Philip C Hill
McAuley Professor of International Health
James E. Ussher; Ayesha J. Verrall
Otago Medical School, University of Otago, PO Box 56, Dunedin 9054, New Zealand
Re: Covid-19: Johnson is on back foot over next steps to control pandemic
Dear Editor
By achieving capacity to conduct 200,000 tests for COVID-19 per day and employing 25,000 individuals to do contact tracing, the UK is in a strong position to “go after the virus,” as Dr Mike Ryan has put it. However, the system will need to operate at the quality and capacity that is needed.
WHO surveillance statistics (1) suggest that both rapid case diagnosis and contact tracing are important for COVID-19 containment. The experiences of Hubei province in China and many other countries show that just diagnosing and managing unwell cases leads to disaster. However, data from provinces in China outside of Hubei and from South Korea show that large outbreaks can actually be brought under control (2). China and other successful countries such as South Korea, Taiwan, Singapore, Australia and Iceland, have had Rapid Case Contact Management as the central component of their response. They have had different approaches to border control, school closures, the use of face masks, and social distancing. Rapid Case Contact Management was described by Drs Aylward and Liang as comprising 90% of the Chinese national response (3). Its efficacy may increase when enhanced electronically (4) and if it is operating within a context of general social distancing measures.
Two key properties of SARS-CoV-2 also suggest that both rapid case diagnosis and contact tracing are important. Firstly, SARS-CoV-2 has peak transmissibility very early after the development of symptoms (5), whereas the SARS-CoV-1 did not reach peak transmissibility for at least 6 days after symptoms developed. This means that a strategy limited to just diagnosing cases leaves it too late to stop ongoing SARS-CoV-2 transmission. Secondly, SARS-CoV-2 has a mean incubation period of 5-6 days (6), whereas H1N1 influenza virus tends to cause disease within 2-3 days. This means that there is more time to find all the contacts of a COVID-19 case and place them in quarantine. However, clearly a high proportion of cases must be diagnosed and isolated early in their illness, and contacts must be identified and quarantined rapidly.
Rapid Case Contact Management does not need to be perfect, but it needs to operate at high quality across the system, even in the presence of large numbers of COVID-19 cases. We have developed a framework to optimise the quality of tuberculosis case contact management thatcan be adapted for COVID-19 (7). Simple epidemiological tools are applied to gather data related to performance indicators (8). Performance failure is then analysed and options assessed for closing the gaps that are identified. We propose 10 system performance indicators for the COVID-19 Rapid Case Contact Management system, along with proposed target measurements, below. The target measurements have been created on the basis of the following principles. Firstly, contacts should be placed in quarantine before the average incubation period of the virus, and for a duration 14 days since their last exposure. Secondly, pragmatically, some activities require more person-time to complete than others do. Finally, modelling suggests that over 80% of contacts need to be promptly traced and quarantined for an outbreak to be controlled (9). Of note, in a high performing system, contact tracing reduces the average time from the development of symptoms to testing in cases.
If the UK can diagnose a high proportion of COVID-19 cases quickly and quarantine their contacts rapidly and effectively, with augmentation by other measures (especially electronic enhancement and social distancing), this could be the key to protecting the population until an effective vaccine and/or therapeutics are available.
Ten performance indicators and their targets for Rapid Case Contact Management of COVID-19:
1. Number of cases able to have contact tracing completed/day
Rationale: Ensures adequate capacity to conduct quality rapid case contact management
Target: At least 200 cases/million population and their contacts within 5 days
2. Percentage of prospective cases who should have a test, who have a test done
Rationale: A high proportion of cases need to be detected
Target: >90%
3. Time from prospective case symptom onset to test
Rationale: Late detection delays case isolation and potentially increases number of contacts
Target: <2 days in >80%
4. Time from prospective case sampling to test result
Rationale: Slow turn-around times delay case isolation and contact tracing
Target: <24 hours in >80%
5. Time from PHU notification of case to contact identification
Rationale: Delayed notification case isolation compromises effectiveness of contact tracing
Target: <12 hours in >80%
6. Percentage of identified contacts who are traced, stratified by household or close contact
Rationale: Failure to complete contact tracing increases the likelihood of onwards transmission
Target: >80%
7. Time from contact identification to isolation
Rationale: Timely contact tracing prevents onwards transmission
Target: <24 hours in >80%
8. Percentage of contacts quarantined within 3 days of symptom onset of index case
Rationale: Contacts should be quarantined within the incubation period of the virus
Target: >80%
9. Percentage of contacts adhering to quarantine
Rationale: Poor adherence risks onwards transmission of the virus
Target: >90%
10. Percentage of contacts of SARS-CoV-2 positive contacts who become SARS-CoV-2 positive
Rationale: This is a sign of failed contact tracing or of failed quarantine
Target: <1%
References
1. World Health Organisation. Coronavirus disease (COVID-19) situation reports: World Health Organisation; 2020 [cited 2020 2 May]. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situatio....
2. Covid-19 National Emergency Response Center E, Case Management Team KCfDC, Prevention. Coronavirus Disease-19: The First 7,755 Cases in the Republic of Korea. Osong Public Health Res Perspect. 2020;11(2):85-90.
3. World Health Organisation. Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). Geneva: World Health Organisation; 2020 28/02/2020.
4. Ferretti L, Wymant C, Kendall M, Zhao L, Nurtay A, Abeler-Dorner L, et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science. 2020.
5. Wang Y, Wang Y, Chen Y, Qin Q. Unique epidemiological and clinical features of the emerging 2019 novel coronavirus pneumonia (COVID-19) implicate special control measures. J Med Virol. 2020.
6. Zhang J, Litvinova M, Wang W, Wang Y, Deng X, Chen X, et al. Evolving epidemiology and transmission dynamics of coronavirus disease 2019 outside Hubei province, China: a descriptive and modelling study. Lancet Infect Dis. 2020.
7. Hill PC, Rutherford ME, Audas R, van Crevel R, Graham SM. Closing the policy-practice gap in the management of child contacts of tuberculosis cases in developing countries. PLoS medicine. 2011;8(10):e1001105.
8. Rutherford ME, Ruslami R, Anselmo M, Alisjahbana B, Yulianti N, Sampurno H, et al. Management of children exposed to Mycobacterium tuberculosis: a public health evaluation in West Java, Indonesia. Bull World Health Organ. 2013;91(12):932-41A.
9. Hellewell J, Abbott S, Gimma A, Bosse NI, Jarvis CI, Russell TW, et al. Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts. Lancet Glob Health. 2020;8(4):e488-e96.
Competing interests: No competing interests