Saturday , June 25 2022

Covid-19: New strategy could overwhelm the contact tracing system



The government has criticized the country’s contact tracing and testing systems as it strays from the qualifying process.

ANALYSIS: The Ministry of Health has not increased its contact tracing capacity since it was criticized by an expert review in June, although the new Covid-19 suppression strategy may see its monitoring system overwhelmed.

If the government does not do so despite the recommendations of several critical reviews of the monitoring system, it will have to rapidly increase its capacity to contact the trace.

Pool photo: Robert Kitchin

If the government does not do so despite the recommendations of several critical reviews of the monitoring system, it will have to rapidly increase its capacity to contact the trace.

Philip Hill, a public health expert at the University of Otago and co-author of a series of critical reviews of the contact tracing system, said: newsroom The ministry turned out to be “in conflict” with a ministerial directive to increase capacity.

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One such report, which reviewed the response to the February outbreak and was published in July, found that “New Zealand would struggle to sustain high system performance of contact tracing over an extended period of time with 100-200 cases per day.”

At issue is a recommendation that goes back to April 2020, when the Government can trace contacts of 1,000 new cases per day. This recommendation came from Ayesha Verrall, then a public health expert in Otago, now Deputy Minister of Health, and was based on the assumption that each case could have up to 36 contacts per day.

The Ministry of Health was reluctant to create such surge capacity. According to the elimination strategy, New Zealand was unlikely to reach such case numbers. But with the shift to pressure, where ministers no longer expect to bring the number of cases in Auckland down to zero, there will always be a risk of an epidemic spiraling out of control.

The ministry spokesman insisted that the current increase capacity – handling 6,000 new contacts each day – is in line with the 1,000 cases per day threshold if each case has six contacts.

This figure has not changed since the beginning of the epidemic and shows that despite the transition to suppression, no improvement in contact tracing capacity has been made.

The problem is that during the current outbreak, each case has produced, on average, at least 28 contacts. This means that current contact tracing capacity can only handle 214 new cases per day – a number the country can exceed under pressure.

Also, if restrictions continue to be relaxed in Auckland, more contacts could be made as people go out.

Of the 612 cases detected in the first two weeks of the outbreak, most infected during Level 1 and visiting attractions during that time, each resulted in an average of 56 contacts. Under this scenario, contact trackers will be overwhelmed if daily cases rise well above 100.

“If the number of contacts the ministry can track is what you describe, they do not seem to have increased the capacity of the testing and monitoring system since our last report to the minister on June 4,” Hill said. newsroom.

“In particular, we presented a benchmark calculation of around 10-30 contacts per case, so if there are 1000 cases per day, 10,000 to 30,000 new close contacts per day should be able to be managed by the system. That would equate to something. Between level 2 and 3 alert level status. There is some confusion in his definition of transient contacts as close contacts, but the benchmark calculation is a good reference for estimating system capacity.”

In other words, the ministry’s current surge capacity may be five times smaller than needed.

Hill expressed concern in the current outbreak, where contact tracing has been slow to scale up and thousands of potential contacts of COVID-19 cases have yet to be contacted more than a week after they were first exposed.

“We have warned earlier in each of the three previous reports since mid-2020 that if capacity is not significantly increased, New Zealand will have a hard time dealing with a major outbreak,” he said in August.

“We haven’t seen how this has been addressed since the report presented in early June this year.”

The expert went further in his comments. newsroom On Thursday, he said his expert review panel reached out to the Civil Service Commissioner after the ministry refused to implement a ministerial directive on 1,000 cases a day.

“We were sufficiently concerned about the department’s decisions on capacity to contradict the ministerial directive, we asked the head of civil service, Peter Hughes, for assurance that he would check that it was appropriate and act accordingly,” Hill told us. newsroom.

Contact tracing is not the only system under scrutiny in recent days as the government prepares to move on to addressing more Covid-19 cases in the community.

New Zealand’s testing strategy was the focus of a critical review released by the Government on Thursday. It found that the government was slow to introduce new testing technologies such as saliva testing or rapid testing. He also recommended establishing a new testing strategy for New Zealand as we hope to see more cases in the community.

Verrall on Thursday said he didn’t know when the new strategy might go live. However, it will need to involve some changes, not only in the more widespread use of new technologies, but also in targeting testing to areas and cases where it is most needed.

Past outbreaks have seen a wave of testing and long car queues outside test centers. Such reactions are understandable but not sustainable if there are always cases occurring in the community. Instead, testing will need to target the most relevant outbreaks and contacts most likely to develop into new cases.

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