Fifteen cases of Covid-19 have been detected in the Co Down town of Kilkeel following localised testing in the area.
The Public Health Agency (PHA) said that just over 1,000 tests were carried out over the weekend and 15 positive cases of Covid-19 have been detected.
The positive test results are being assessed to ascertain whether the cases are of the Delta variant of the virus first identified in India.
Asymptomatic testing started in Kilkeel on Saturday following the identification of a small number of probable cases of the variant.
Testing Units are to remain in Kilkeel to accommodate testing of anyone over the age of five from within the identified areas who has yet to be tested.
The PHA is also working with partners to place an additional Mobile Testing Unit at Kilkeel High School to test all pupils and staff as a precautionary measure as a number of positive Covid-19 cases have been linked to the school.
The Delta strain is up to 40-50 per cent more transmissible than the Alpha mutation which caused an alarming spike in cases before Christmas.
That mutation, which was previously known as the Kent variant, was already as much as 70 per cent more transmissible than the original coronavirus which started the lockdown in 2020.
The Delta variant has also seen those infected twice as likely to be hospitalised - especially if they haven't been vaccinated or have only received one dose.
Asymptomatic people have been asked to volunteer to be tested as a "precaution" to identify cases and prevent spread.
The first cases of the variant were confirmed in Northern Ireland in early May, with 26 cases since established across the region.
It is now the dominant strain in the UK.
