BMJ: To curb the spread of COVID-19, intervention based on symptoms and cases is not enough

Detection, tracking and isolation programs are important interventions to control the epidemic of infectious diseases, especially those related to emerging pathogens.

Smith and his colleagues used data from 37 online surveys in the United Kingdom to report the performance of the detection, tracking and isolation system in the first 11 months of the British covid-19 pandemic.

What do the results of this study tell us about the implementation of the covid-19 detection, tracking and quarantine system in the UK?

What do the results of this study tell us about the implementation of the covid-19 detection, tracking and quarantine system in the UK?

A simple calculation shows that 50% of the respondents can identify the symptoms of covid-19, 20% of the respondents will seek a covid-19 test if they have symptoms, and 80% of the respondents will share close contacts if they test positive.

Since the basic reproduction number of covid-19 is estimated to be between 2 and 3, or even higher, at least 50-66% of the transmission needs to be interrupted in order to reduce the effective reproduction number below the critical threshold of 1.

Percentage of people with the most common symptoms of covid-19

Percentage of people with the most common symptoms of covid-19

The percentage of people who have not left home since they developed symptoms of covid-19 ( the number of people who developed symptoms of covid-19 in the past 7 days, excluding those who have tested negative for COVID-19 since the onset of symptoms ), and report if COVID-19 has occurred People whose symptoms do not intend to leave home (people who have not had COVID-19 symptoms in the past 7 days).

The percentage of people who have not left home since they developed symptoms of covid-19 ( the number of people who developed symptoms of covid-19 in the past 7 days, excluding those who have tested negative for COVID-19 since the onset of symptoms ), and report if COVID-19 has occurred People whose symptoms do not intend to leave home (people who have not had COVID-19 symptoms in the past 7 days).

The proportion of people who requested testing after they developed symptoms of covid-19 (experienced symptoms of covid-19 in the past seven days) and who planned to request testing if they developed symptoms of COVID-19 (have no symptoms of covid-19 in the past seven days).

The proportion of people who requested testing after they developed symptoms of covid-19 (experienced symptoms of covid-19 in the past seven days) and who planned to request testing if they developed symptoms of COVID-19 (have no symptoms of covid-19 in the past seven days).

The percentage of people (those who have not experienced covid-19 symptoms in the past 7 days) who may or will share details of their close contacts if they have been contacted through the NHS contact tracing service.

The percentage of people (those who have not experienced covid-19 symptoms in the past 7 days) who may or will share details of their close contacts if they have been contacted through the NHS contact tracing service.

Pay attention to health transmission to improve the understanding of symptoms and reduce the barriers to diagnostic testing.

Infection before symptoms transmission accounted for a large percentage of all propagating (up to 40%) symptoms before transmission accounted for a large percentage of all propagating (up to 40%)

Considering the extent of pre-symptomatic and asymptomatic transmission of covid-19, as well as the potential loss of the full chain reaction of detection, tracking and isolation, the true impact of the detection, tracking and isolation program may even be lower than the results of Smith and colleagues' research.

Interventions based solely on symptoms and cases are extremely unlikely to contain the covid-19 pandemic.

The combined use of vaccination, case-based interventions and population-based interventions provides the best opportunity for continuous covid-19 control.

Innovative methods, including digital contact tracing, are expected to make more effective use of resources and improve the effectiveness of detection, tracing, and isolation in public health systems with limited resources.

Smith LE, Potts HWW, Amlôt R, Fear NT, Michie S, Rubin GJ.

Smith LE, Potts HWW, Amlôt R, Fear NT, Michie S, Rubin GJ.
Adherence to the test, trace, and isolate system in the UK: results from 37 nationally representative surveys.
  BMJ .
2021;372:n608.
Published 2021 Mar 31.
doi:10.
1136/bmj.
n608 Smith LE, Potts HWW, Amlôt R, Fear NT, Michie S, Rubin GJ.
Adherence to the test, trace, and isolate system in the UK: results from 37 nationally representative surveys.
  BMJ in This message