An extended household and workplaces are behind a rise in Covid cases in Merthyr Tydfil, a health chief says.
The flare-up is down to “a bit of a loss of discipline”, Dr Kelechi Nnoaham, director of public health for Cwm Taf Morgannwg health board, said.
Localised hotpot Gellideg and Merthyr Town has had 47 cases in the past week, half of those in the county.
The area has a seven-day case rate of 669.3 per 100,000 population compared to the Wales average of 42.5.
Covid rules currently allow most to only meet indoors with people they live with.
Merthyr council has responded by deploying a mobile testing unit to the Swansea Road estate.
Dr Nnoaham told BBC Radio Wales Breakfast with Claire Summers: “We have identified about four different clusters that are largely responsible for the increase in cases that we have had.
“We know that a number of workplaces have been involved in this cluster, we know there has been an extended household cluster in one of the areas.
“I think we understand exactly why this has happened and I just want to use the opportunity to appeal to people out there that whilst we’re making progress in the vaccination programme we’re by no means home and dry and we still need to maintain those precautions and be extra vigilant.”
He said the spread was largely down to young people in the area.
“When we looked at the age profile of the majority of the cases and these clusters, what we’re talking about is largely young people who have not had their vaccination,” he said.
“And secondly, it does appear that the loss of discipline around the social distancing facemasks has been more likely in the younger populations.
“There’s a bit of a loss of discipline that has happened more recently”.
He urged people to watch Saturday’s Grand Slam between Wales and France at home and not with friends and family.
Only those who live alone, are single and live in a house share, single parents and 16 and 17-year-olds who do not live with an adult had been able to form a so-called “support bubble”.
Four people from two households can meet outdoors to socialise, including in gardens.
The case rate in the county of Merthyr Tydfil continues to rise, up from 147.5 on Tuesday to 155.8 per 100,000 people as of Wednesday, with the community again having the highest case rate in Wales.
This is the highest point reached locally in the last six weeks, but still a long way from the levels seen in previous months.
It hit a peak of 1,349 cases per 100,000 – the UK’s highest – one week before Christmas.