How to get out of lockdown earlier

Infectious diseases doctor says without more efficient contact tracing we’ll be in lockdown longer. David Williams reports.

Without a country-wide lockdown tens of thousands might die from Covid-19, Prime Minister Jacinda Ardern said on Monday.

“The worst-case scenario is simply intolerable,” she said of the medical modelling she’d received.

“It would represent the greatest loss of New Zealanders’ lives in our country’s history. I will not take that chance.”

The four-week lockdown, which starts tonight, is a response to the crisis a widespread community outbreak would have caused.

Dr Ayesha Verrall, of University of Otago, Wellington, is sure this country will get on top of coronavirus. The infectious diseases doctor and epidemiologist says the question is, how long does the country spend in lockdown to achieve that?

“How do we get out of this position to a position where we can go back to normal life? There really is only one answer, which is contact tracing.”

“Every delay gives the virus another chance to get ahead of us.” – Ayesha Verrall

Contact tracing is the painstaking work undertaken by public health officials to find who confirmed cases have been in contact with while infectious.

At highest risk are close contacts, those in close quarters for longer than 15 minutes, like those we live with, work with, or sit next to on the train. (Casual contacts, like someone two rows back on a plane, are at lower risk.) Finding close contacts and isolating them helps slow the spread of an outbreak.

We’re considered infectious in the 48 hours before symptoms – fever, cough, or shortness of breath – develop, and 48 hours after they’ve gone.

Verrall says it can take five nurses two days to trace all the contacts of a confirmed case. “And you can imagine if we’ve got 40 new cases reported then that’s a massive workload for the small number of public health staff we have in our public health units.”

The risk of slow contact tracing is that by the time someone is called because they’re a close contact of an infected person they might already feel feverish, and have passed the virus to other people. “Every delay gives the virus another chance to get ahead of us,” she says.

There have been 76 new confirmed cases in this country in the previous two days, bring the total of confirmed and probable cases to 155. The vast majority have been people arriving from overseas, but there are now four cases of community transmission – those that can’t be linked to overseas travel or an existing confirmed case.

“Remembering that China turned around an outbreak of hundreds of thousands, it is totally within our power to turn around an outbreak with four,” Verrall says. “But we need to be using this time to build up our ability [on] those cases and contacts, and also to make sure we’re addressing any blindspots we have in our ability to identify cases.”

Privacy versus time in lockdown

Beyond China, where the first case was reported in December, other countries have had relative success in containing coronavirus.

In Taiwan (215 confirmed cases, two deaths), phone tracking is used to check compliance of its mandatory quarantine measures. It was also quick to implement border controls. Singapore (509 confirmed cases, two deaths) is using a similar system, in which those in isolation click on text messages so health authorities can pinpoint the location of their mobile phone. (Both countries learned painful lessons during the 2003 outbreak of severe acute respiratory syndrome, or SARS.)

“The greater the potential impact on public health, the more important issues we have to work through about privacy,” Verrall says.

“The question we have to ask is would we rather choose to forgo some data privacy, with protections, or would we rather spend time in lockdown – because those are the options really.”

This country’s Ministry of Health has set up a centralised team that can manage the contact tracing of an extra 50 new cases a day.

But Verrall says the country needs to be able to trace up to 1000 new cases a day, using a range of different methods.

“We need a massively enlarged central call centre, we need additional staff in public health units – because you will always need a real person to deal with complicated situations – and thirdly we need digital technology that can automate at least part of the process using smart phones.”

Asked yesterday how long it takes from being swabbed to a confirmed result, Director-General of Health Ashley Bloomfield avoided answering directly, saying that depends on where the swab was taken. He noted there were five laboratories processing tests across the country. “We would be aiming to get from the swab to the test result being notified to the patient within 48 hours.”

Now the country has passed 100 cases – an important epidemiological milestone – Verrall expects the Government to report on the time it takes to contact trace, and other important details.

Verrall says it should take three or four days from when sick people are tested to contact tracing being completed. In Wuhan, the capital of Hubei province in China, they had more than 5000 people contact tracing, she says.

“In Singapore, when they started doing this it took 12 days on average to trace a case. Now they’ve pulled it down to about three days. We need to see that system as an engineering problem that we’re going to maximise how quickly people move through that system.”

She adds: “We need to use all the tools we possibly can to lift our numbers. That will be a mix of people on the ground, people in call centres, plus technology.”

Tracking a return to normal

Bloomfield said yesterday a lot of work goes into actively tracing back through the chain of recent interactions by infected people, with close contacts being put into isolation, and monitored.

(While many people who develop coronavirus will experience only mild or moderate symptoms, some – especially older people, and those with weak immune systems or pre-existing health conditions – will become seriously ill and be hospitalised. The virus is thought to mainly spread through touching infected surfaces.)

The advantage of this country having a system with a quick turnaround of lab tests, fast contact tracing, and remote tracking of those in quarantine, is an earlier return to normal life.

In Taiwan, offices and schools are open, as are restaurants, gyms and cafes – although patrons will likely have their temperatures checked and hands sprayed with sanitiser before entering.

Verrall says this country’s virus containment system needs to be improved during the looming four-week shutdown.

“The ability to contact trace is related to how many cases we can manage in the community without being in lockdown. If we could contact trace more efficiently we would be able to have small clusters or outbreaks in the community and have our businesses and schools open.”

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