Plans to reduce pressure on the NHS and increase access to tests for people with symptoms have been put in place with immediate effect.
Health and Social Services Minister Eluned Morgan said: "As the omicron wave sweeps across the country demand for PCR testing has reached unprecedented levels across the UK. This has resulted in the UK Health Security Agency (UKHSA) constraining bookings at times to avoid exceeding the UK programme laboratory capacity and compromising turnaround times for results.
"Since Christmas Day, daily bookings at tests sites across Wales have reached up to 28,000 – a record high.
"I have agreed some immediate changes to the PCR testing system that will help reduce pressure and help increase access for those who have symptoms and need to book a test.
"The first change will mean that people who are un-vaccinated contacts of positive cases and are self-isolating for 10 days should now take a lateral flow test on day two and day eight instead of a PCR test. This will help to increase PCR testing capacity. This change will come into effect immediately.
"Secondly, together with the other UK nations, we have agreed that if a person showing no symptoms has a positive lateral flow test they will no longer be advised to have a follow-up PCR test to confirm the result, unless they are in a clinically vulnerable group, which may need early access to treatment or have been advised to do so as part of a research or surveillance programme.
"As the prevalence of coronavirus is above 1%, the risk of false positives from lateral flow devices decreases. This means there is less value in having a follow-up PCR test to confirm the result. At higher prevalence levels, data suggests that lateral flow tests and PCRs have a similar positive predictive value.
"This change will come into effect from 6 January and we estimate it will reduce the demand for PCR tests by between 5% and 15%.
"Without a follow up PCR tests it is even more important for people to report the result of every lateral flow test they do and self-isolate as soon as they test positive. Without reporting, contact tracing will not be possible, nor will advice and support be provided by the system.
"We need everyone to continue to play their part in disrupting the transmission of Covid-19 by reporting their lateral flow test results on the gov.uk website or by calling 119.
"Positive results from lateral flow tests already flow into the Wales contact tracing system to speed up the contact and support required to help all those who need to self-isolate.
"NHS and social care staff access testing from our NHS Wales laboratories. We may need to introduce further changes to protect PCR tests for key workers through the UK testing programme if demand continues to grow in the coming days and weeks.
"We may also need to introduce other temporary emergency interventions for non-vulnerable symptomatic individuals to manage demand and safeguard capacity to find the cases most likely to result in harm.
"We recognise these changes will potentially increase demand for lateral flow tests. There are no current issues with supplies but we are aware of issues with distribution for people to access tests at some collection points including pharmacies. UKHSA manage the logistics and deliveries across the UK and we are working closely with them to improve the situation. More than 4 million tests were distributed to workplaces, people’s homes and collection points in Wales last week.
"This statement is being issued during recess in order to keep members informed. Should members wish me to make a further statement or to answer questions on this when the Senedd returns I would be happy to do so."