What is causing the slowdown in the test and trace system?

With turnaround times slowing, the country’s system for testing and tracing for Covid-19 is again coming under scrutiny.

Questions are being asked about whether it is up to the task of severing the chains of transmission, and facilitating vital steps such as the reopening of schools in less than a fortnight. Just what is happening in the testing and tracing system, and can it handle the pressure?

What is causing the slowdown?

Put simply, there is more disease in the community. This means more testing to be done, more cases to be managed, more contacts to be traced, and more pressure on the system. With 1,250 cases in the last 14 days, about 2 per cent of tests are now coming back positive.

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The number of contacts being traced has risen significantly, with up to 50 close contacts in some instances. On August 4th, there were 260 calls being made per day by contact tracers, with 800 being placed last Sunday.

What’s happening on the frontline?

Prof Mary Codd, who runs a contact tracing centre at UCD, says that contact tracing is holding up under pressure. However, she says the days since the UCD centre was reopened on August 9th have been "unbelievably intense", with numbers of contacts being traced "off the scale" compared to what was seen in lockdown.

“We have seen lots of gatherings of family and friends which have resulted in wide dispersions of contacts, from gathering in a holiday location in one part of the country to the north, west, south and east.” What that means, she says, is that the virus is “widely dispersed through a multiplicity of contacts in a variety of settings”.

What exactly happens with a test?

There are three steps: sampling, analysis and contact tracing.

For members of the public, you are either tested at a sampling centre, or at home by the National Ambulance Service. Those in residential settings like nursing homes are tested there, and some sectors like meat plants are being serially tested on a rolling basis. Healthcare workers have a fast track for testing.

It is then sent for analysis at a lab, and if positive, the sample is contact traced. Contact tracers undertake three sets of calls: to alert the person diagnosed, then to assess their close contacts, then to their close contacts.

How long does it take?

People are again beginning to share stories of waiting days for tests and results. One person based in Dublin, whose entire family was mildly symptomatic, told The Irish Times they were referred for a test last Friday afternoon, but were only tested on Monday afternoon.

Anecdotes are not data but figures show there has been slippage. From referral to getting an appointment, the average time is now 0.9 days, with average swabs taking 1.3 days to get a lab result. On average, it is taking 1.8 days to complete all contact tracing calls. While this would suggest an overall time of four days, the HSE says adding these figures together doesn’t give the full picture, and says the median end-to-end time is 2.83 days. This specific figure is not a regularly published number on the HSE’s dashboard, but it is just under the three-day target the HSE has set itself for 90 per cent of cases, which is recommended by experts.

However, one thing is clear from looking at the data, things are getting slower. The HSE says this is due to more people testing positive as the disease circulates.

What is being done about it?

The HSE says that it has enough capacity in the system to test all those who need a test, and can do 15,000 a day. For three of the past four days on which data is available, more than 10,000 tests have been taken, indicating that while the load on the system is substantial, it is not yet at its limit.

More contact tracing centres are being brought on stream to make calls; up until August 9th, there was just one operating, when a second centre at UCD was brought on stream. Last week, centres operated by the Revenue Commissioners in Galway and Dublin were recommissioned, and the Army band was drafted in to provide extra support.