Testing of close contacts ceases as Covid cases under-reported by 4,000

Lag between test becoming positive and result being recorded in system over past three days

The number of confirmed cases of Covid-19 in recent days is under-reported by an estimated 4,000, due to delays in recording positive test results on the system over the Christmas period, a senior health official has said.

Prof Philip Nolan, chair of the Nphet Irish Epidemiological Modelling Advisory Group, said the epidemiological situation has deteriorated rapidly over the past week, and that we are "clearly in the midst of the third wave".

He said the reproductive number is at least 1.6 to 1.8, and the daily growth rate is estimated at 7 to 10 per cent, giving a doubling time of seven to 10 days or less.

Hospital Report

There were 1,620 confirmed cases of Covid-19 in the Republic reported on Thursday.

However, Prof Nolan said the true number of positive cases is higher than has been reported, due to a lag between a test coming back positive and being reported in the system.

He said this situation arose because “very few people” presented for tests on Christmas Eve, Christmas Day and St Stephen’s Day. However, immediately after Christmas, there were very large numbers testing, creating an “artificial surge” in tests.

“We know of additional positive tests that have yet to be reported on the system over the last few days. On the 28th of December there were 2,000 positive tests and the 29th of December there was almost 3,000. Yesterday, the 30th December, there were 4,363 positive tests recorded,” he told the Nphet briefing on Thursday evening.

“Those Covid positive tests are not necessarily cases. Those positive tests have to be validated . . . but many of them will turn into cases. We estimate that there is somewhere in the region of 4,000 positive cases in the last two to three days which have yet to be formally confirmed. They will be confirmed in the coming days.”

Prof Nolan said that this lag “in no way interferes” with identifying cases, but acknowledged the epidemiological situation is “somewhat worse” than has been reported.

“This system wasn’t designed to report 2,000, 3,000 or 4,000 tests per day. We expect to see very high case counts and very high five-day moving averages over the coming week to 10 days,” he added.

Contacts

Meanwhile, Chief Medical Officer Dr Tony Holohan has announced that close contacts of a confirmed case will no longer be tested due to increased demand on the testing and tracing service.

Close contacts will still be identified and requested to restrict their movements for 14 days.

“It’s simply about the scale and the volume. We are at a point now where it’s simply not possible for us to identify every single contact and test every single contact the way we were doing at lower levels of transmission,” he said.

“Just take the numbers that we have, if were identifying three, four, thousand cases through positive testing a day and each one of those is generating on average now 6.3 contacts. That’s well over 20,000 tests a day being generated as a result of testing contacts.”

Dr Holohan acknowledged that this changes makes the accuracy of the daily confirmed figures “a challenge”.

However, he said they think it is important to focus the testing capacity on individuals who are symptomatic, rather than contacts.

“We are effectively asking the entire population to isolate themselves.”

Shauna Bowers

Shauna Bowers

Shauna Bowers is a reporter for The Irish Times

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