It's difficult to tell a true positivity rate on Covid-19 tests, and even more difficult to say it's leveling off, according to an immunologist.
It's after Tánaiste Leo Varadkar said cases and the positivity are starting to stabilise.
15.4% is Ireland's weekly positivity rate and hasn't been below 15% since November 14th.
DCU immunology Professor Christine Loscher explains that the number is "the percentage of people who go for tests who test positive. So if 100 people go for tests, and 15 test positive - we're having a positivity rate of 15%."
The first wave and the third wave saw weekly positivity rates higher than we're experiencing now.
In April 2020 it hit a peak of 23% and in January 2021 it was around 22%.
However, there are caveats to those numbers.
On both occasions, a GP referral was needed to go forward for a PCR test which means asymptomatic people were not being screened.
And in January 2021 the testing of close contacts was also suspended, which would increase the chance of catching a Covid-19 case, as those who were presenting had symptoms and were a suspected case.
However now, anyone can get a PCR test if they're able to get a booking.
It's impossible to have a true positivity rate - however, it's accepted the higher it is, the more Covid-19 there is in the community, and the more that could be missed.
A low positivity rate suggests enough tests are being administered and the vast majority of cases are being identified - particularly those with symptoms.
The World Health Organisation has said throughout the pandemic that a test positivity rate of higher than 5% means the spread of Covid-19 is out of control.
Tánaite Leo Varadkar says the positivity rate is "starting to level off" at 15% - which is statistically true, but as Professor Christine Loscher explains, it doesn't paint the full picture:
"Very difficult to tell whether the 15% positivity rate is a real rate because people are having problems accessing testing.
"But it still tells us the rate of Covid in our community is very, very high at the moment.
"It looks like the positivity rate has been climbing for weeks and months. And has come to a standstill around 15%.
"It's very difficult to say if the positivity rate and case numbers are leveling off, or whether our testing capacity has been reached and our delay in testing is making that positivity rate standstill."
"We can't really make any big decisions or big statements based on individual days or snapshots in time."
