During the last week the most interesting piece of information I heard about dealing with the coronavirus was not who is to blame for the mess in nursing homes, or who let the passengers off the Ruby Princess, it was a short interview of Professor Michael Toole, epidemiologist at Burnet Institute, by Patricia Karvelas – Unknown COVID sources have experts worried.
Toole lays down some markers for effective testing, tracing and isolating.
He said that after a test, the results should come back and 90% of the contacts should be traced and found within 48 hours at a maximum.
He is not talking averages here, he is saying that after you do the test the longest it should take to trace and interview 90% of contacts is just 48 hours.
If you meet that standard, he says, the infection rate will be reduced by 80%. He was using plain language rather than jargon. As an example he said that if you test 10 positives, then trace and isolate 90% of the contacts of those positives within 48 hours, only two more people will become infected.
If, however, you take three days, then nine will be infected.
He said that under normal conditions every positive will have had 5 to 10 contacts. Under Stage 4 lockdowns as in Melbourne now, that reduces to 2-3.
He said that the goal was to reduce the mystery cases in the community to zero. ‘Mystery’ here means that you know that the infected person has not been infected by any known hotspot. Currently NSW was experiencing on average about one mystery case per day. Prior to Stage 4 in Melbourne they had 3000 mystery cases on their books, which were presumed to have up to 30,000 contacts.
They lacked the capacity to do the necessary tracing. In practice, the system had simply been overwhelmed.
Toole does not speak as an insider. He said there was no public information available as to how long testing and tracing was taking in Victoria.
Toole gave two country examples. First, South Korea (population about 51 million). South Korea had suppressed the virus to around 40 to 60 new cases per day, and had worked hard on testing, tracing and isolating, so the were able to keep the virus suppressed to this level for three months or more. (See worldometer site.)
South Korea had kept its economy relatively open, and were willing and able to put in the effort to keep it that way.
Second, Israel (population around 8.8 million) by contrast had a successful response at first, but then there was a second wave, where the 7-day moving average got out of control, but now seems to be stabilising at over 1400 per day. Toole said they lost control of testing, tracing and isolating during the second wave, so they just gave up.
Israel were early movers, and had strict lockdowns and travel movements in March and April. By early May they had suppressed the virus to about 15 per day.
I took a look and found that PM Benjamin Netanyahu had told Israelis to have fun when they opened up in May, and they did. Given what is said elsewhere, it is notable that they think schools have mainly brought them undone.
By early July the health chief quit.
Since then there have been protests, but this running report and this official site indicate that Israelis have little taste for a further lockdown and seem prepared to live with a comparatively high level of infection.
Among all that there was an aim to return test results within 36 hours.
To return to Toole, he does think Victoria’s testing, tracing, isolating regime needs a re-set.
Elsewhere Toole has supported wearing masks, and taking all means possible to defeat the virus, including community engagement and involvement in the design and delivery of messages.
Incidentally, Toole has discovered a trick to stop his glasses from fogging up:
- wash the glasses in soapy water and leave them to air dry. That leaves a film that prevents fogging.
Testing in Victoria has been running at around 25,000 per day (from this ABC site), more than in NSW or, in relation to population, in Queensland.
Toole’s work raises the question as to whether Victoria would be better off with more rapid and targeted testing. I recall Dan Andrews saying recently that their average was two days, at a time when some people were complaining that they waited more than five days for a result.
During the recent mini-outbreak in Queensland, from memory, test time blew out to 39 hours. Apart from that, in the US the test time was never good, and recently was said to be averaging about 7 days, which must be close to useless in terms of virus suppression. My recall is that the Chinese during thew Wuhan crisis had testing time down to about four hours.
Today at Andrew’s press briefing, he said that two weeks ago, when masks were made mandatory, the virus reproduction rate was around 1.0 or a little below. Toole is showing how that rate might be reduced to 0.2.
Clearly not enough attention is being paid to this aspect of coronavirus control.