Everyone living or working in the lower Cynon Valley will be offered a coronavirus test, as the area becomes the second in Wales to introduce mass testing.
All residents and workers without symptoms will be offered repeat coronavirus testing between December 5 and December 20 in a bid to identify positive cases and break the chains of transmission.
Testing will be delivered in partnership between the Welsh Government, UK Government, Rhondda Cynon Taf County Borough Council, Cwm Taf Morgannwg Health Board and the Ministry of Defence, with logistical support from the Armed Forces.
The areas covered by the mass testing pilot are Abercynon, Mountain Ash East, Mountain Ash West, Penrhiwceiber and Aberaman South.
Two main test centres will be located at Cynon Valley Indoor Bowls Centre and Mountain Ash and Abercynon Sports Centre, with further sites announced at a later date.
Lateral Flow Devices, which can turn around results within about 20 to 30 minutes, will be used to test people.
If a person tests positive, they will be asked to return home so they can self-isolate immediately.
Health Minister Vaughan Gething said: “The pilot in Merthyr continues to go well with almost 8,000 tested in the first six days of the pilot.
“I’m pleased we are now able to extend the mass testing programme to Lower Cynon Valley.
“As the Merthyr Tydfil pilot has shown, mass testing is providing us with a greater understanding of prevalence within the community and how many people have coronavirus.
“It’s also identifying how many people within the community are asymptomatic.
“Coronavirus has not gone away and we all need to work together to tackle this deadly virus.
“I want to thank everyone in Merthyr Tydfil who have made the pilot project a success and I would encourage the people of Lower Cynon Valley to get tested.”
The areas able to access the testing have seen some of the highest incidence rates of coronavirus in recent weeks.
Identifying residents who may have the virus but have no symptoms could be key to helping stop the transmission of Covid-19, the Welsh Government said.
It will be closely monitoring the number of positive results to help better understand the spread of the virus.
Councillor Andrew Morgan, leader of Rhondda Cynon Taf County Borough Council, said the mass testing pilot came following several weeks of planning.
“This is an integral part of our fight against the virus, as it gives us a greater understanding of the prevalence and level of transmission within our communities,” Mr Morgan said.
“Following the positive progress seen in the downward trajectory of daily cases and the positivity rate after both the local measures and the national firebreak lockdown, it is now important that we identify and isolate those who are asymptomatic within our communities to break those chains of transmission as cases are now starting to rise again.”
In the seven days leading up to November 24, the incidence rate in Rhondda Cynon Taf was 252.4 cases per 100,000 people, Public Health Wales figures state.
Of the tests performed, 13.8% came back positive for coronavirus.