Barely half of positive antigen test results confirmed by PCR testing

Average of almost 4,000 antigen tests carried out on close contacts since end of October

Barely half of the positive results from antigen tests carried out on close contacts of Covid-19 cases have been confirmed by further PCR testing.

An average of almost 4,000 antigen tests have been carried out on close contacts who are fully vaccinated and have no symptoms since the measure was introduced at the end of October.

In the first month, 31,850 antigen test results were reported by close contacts - 21,579 “not detected” or negative results, and 10,271 “detected” or positive, according to data presented at a National Public Health Emergency Team (Nphet) meeting this month.

Hospital Report

Just 5,741, or 54 per cent, of these positive antigen test results were confirmed positive with subsequent PCR testing.

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One in five adults (21 per cent) have taken an antigen test for Covid-19 in the previous week, the meeting heard, while 62 per cent of people with symptoms took an antigen test.

Of those with symptoms who took an antigen test and received a negative result, just 39 per cent self-isolated and 26 per cent organised a PCR test.

Demand for testing is higher than it has been at any point in the pandemic and continues to increase, the meeting held on December 2nd heard, with one in every 1,000 children being tested every day.

In a future scenario where the virus becomes endemic, the value of PCR testing every suspected case is likely to diminish and alternative “modalities” of managing it, such as those for seasonal flu, “may be more appropriate”.

Members expressed concern about the “uncertainties” surrounding the Omicron variant, in particular regarding its potential increased growth rate.

“The indeterminate nature of the projections was described as striking with concern expressed for the possible impact on healthcare capacity,” the minutes record. Members queried how modelling was accounting for the potential impact of flu, and asked whether anything could be done to reduce the uncertainty around the proportion of undetected cases, which currently range at 40 to 60 per cent.

Survey

Meanwhile, only about half of people with symptoms are going for a PCR test or self-isolating as recommended, according to polling conducted for the Department of Health.

One in eight adults had symptoms last week that they thought might be Covid-19; 47 per cent of all those with symptoms arranged a PCR test and 52 per cent self-isolated.

More than one-quarter of adults took an antigen test in the last week; 78 per cent people with symptoms took one, and 20 per cent without symptoms. Nine per cent of tests were positive and the rest negative.

According to the Amarach Research tracker for the Department, 88 per cent of people with a positive antigen test and symptoms said they then arranged a PCR test and self-isolated.

However, only 41 per cent of people with symptoms whose antigen test was negative arranged a PCR test, and only 43 per cent self-isolated.

The survey also shows that since last month, sharp upticks have occurred in the proportion of under-35s adhering to public health guidelines, and in people staying at home,.

For the first time since January, more people think the worst of the pandemic is ahead of us rather than behind us, according to the research.

Citizens are having difficulty understanding "where Ireland is on its pandemic journey", the polling also indicated.

“For example, do these high case numbers mean we are back to Square One? Does the Omicron variant mean we are worse than Square One? The country needs help to orientate itself as to where we stand, with regard to our national pandemic journey,” according to the minutes.

Polling also showed that already in early December, the hospitality sector was “heavily impacted”, according to the minutes. Cancellations were running then at about 70 per cent, and there was an expectation the sector would be fully closed down before Christmas.

Many outlets are reportedly “packing them in”, according to the research presented at the meeting. Members decided the biggest contribution to controlled, safe trading was in “re-imagining enforcement” to shift from “sideline-issues” such as the collection of contact tracing details to a focus on capacity.

A detailed discussion on mandatory vaccination for healthcare staff was deferred to a later meeting but Nphet members voice the need for caution on the issue, “given the potential impact this could have on the social solidarity which has been a bedrock of Ireland’s response to Covid-19 to date and has helped to achieve one of the highest vaccination rates in Europe”.

Dr Holohan twice during the meeting reminded members their discussion was “particularly sensitive” and that all information should remain strictly confidential.

Paul Cullen

Paul Cullen

Paul Cullen is Health Editor of The Irish Times