The politics and limits of tracing

Submitted by AWL on 3 June, 2020 - 3:32

The government, and many of its critics too, cite “test-trace-isolate” as almost a cure-all to control the virus while still easing the lockdown.

The labour movement cannot claim expertise on the details. But we must demand that the operation be accompanied by full isolation pay for all, and run as a public-service operation, by public-sector workers on good public-sector terms, not contracted-out.

The idea is people with symptoms like Covid-19 are promptly tested. If they test positive, then they’re asked to list all the people outside their household with whom they’ve been in less-than-two-metres contact for 15 minutes or more over the previous days. The first person, their household, and those other contacts are asked to self-isolate for up to 14 days, so they don’t infect others.

A report (27 May) from a team of scientists with the Royal Society (who support a tracing effort) is useful.

In mid-May, they reckon, there were about 10 cases of Covid-19-like symptoms (cough, fever, etc.) for every one Covid-19 infection. It will be more than 10 in winter. So: test the first person before you start contact-tracing, or otherwise the tracing system will be swamped.

The contacts, in turn, can be tested. But the value of that is limited, because the tests do not detect the virus in the first few days.

The authors reckon that if done well (quick test results, all contacts traced within three days of the symptom report, 80% compliance with self-isolation), tracing will reduce the reproduction rate of infection by between 5 and 15%. Useful but limited. That’s “if done well”, but the Tories plan it as a cheapskate contracted-out casual-labour operation, without solid provision for isolation pay.

Another study (29 May), by Neil Ferguson and others, shows that South Korea’s tracing was deployed efficiently against the virus outbreak in the Shincheonji religious group (which was 48% of all cases up to 11 May). Overall, though, “it is unclear how much the ‘test, trace, isolate’ strategy on its own” helped check transmission “relative to other measures such as social distancing [there was no lockdown in Korea] and regional quarantine”.

South Korea has government surveillance over everyone’s smartphone and payment cards which, together with CCTV, enables the government to trace any infected person’s recent movements within ten minutes of a test result and send out notification texts.

Such surveillance is not available to the British government and would have many downsides.

The Royal Society report praises tracing in Germany, but uses only outdated British press coverage. A more recent, and German, report (14 May) found: “Only 24 percent of [local authorities] meet the [tracing] requirements agreed upon by the federal and state governments... 67 percent do not have enough employees...” Germany has a low case fatality rate for Covid-19, but probably not from good tracing.

Cause for hope is a trickle of research indicating that transmission of the virus is concentrated in “clusters” (as in Korea, or as in the Netherlands, where the big cities, Amsterdam, Rotterdam, The Hague, have Covid-19 hospitalisation rates only one-sixth those in the North Brabant province, bordering Belgium).

One study, by Adam Kucharski and others, estimates that 80% of transmission is generated by 10% of sufferers. Other studies indicate that transmission has been concentrated in hospitals, care homes, some other workplaces notably in the meat industry, and churches.

If that’s right, and if those “clusters” can be tracked and controlled, then tracing may work better

For now, though, Britain ranks bottom but two in Oxford University researchers’ world index of countries’ readiness for lockdown-rollback, and would be below even Iran and Nicaragua were it not that it scores high for “community awareness”: see here.

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