People in two counties are being asked to wear face masks in work, shops and crowded public spaces in a bid to avoid another local Covid-19 lockdown.
Residents of Rhondda Cynon Taff and Merthyr Tydfil have been asked by councils only to use public transport if "essential".
They have already been warned they face lockdown after an increase in cases.
Merthyr Tydfil has the second highest coronavirus case rate in Wales - behind Caerphilly, already in lockdown.
In a joint statement, Merthyr Tydfil and Rhondda Cynon Taff councils, the local health board and police called for local residents to "take action now".
To take affect immediately, they want people to:
- Only use public transport for essential purposes, like travel to education, work, essential medical appointments and shopping
- Work from home for the next few weeks if you can
- Wear a three-layer face mask, in work, supermarkets and other indoor or crowded public spaces for everyone aged 12 and over
- Not to visit care homes, unless it is an end-of-life visit where full personal protective equipment will be required
Both councils said schools would remain open and home-to-school transport would continue "in accordance with the latest Public Health Wales guidance".
Public health chiefs said people "ignoring or disregarding" social distancing was "why transmission has increased" in those areas.
"Our message for the public is that coronavirus has not gone away - and it can be a very serious illness - especially for older and vulnerable people," said Kelechi Nnoaham, public health director of Cwm Taf Morgannwg health board.
"We must all play our part to protect our vulnerable or older friends, family members and loved ones. Whilst we may not be seeing hospital admissions at the moment, it will only be a matter of weeks if we don't act now."
There were almost 3,000 Covid-19 UK confirmed cases in the last 24 hours as cases in Wales reached almost 19,000 on Thursday as 102 new positive cases were reported by Public Health Wales.
Hospital admissions of patients with coronavirus have doubled in the last week in the Cwm Taf Morgannwg health board area.
Six supermarkets in Rhondda Cynon Taff have already been given improvement orders, while warnings were given over a lack of social distancing due to small clusters around Porth, Penygraig and Tonypandy.
The highest rate for cases in Wales remains in Caerphilly county where there have been 91.1 cases per 100,000 of the population over the past seven days.
In Merthyr Tydfil, more than 6% of those tested in the last week had coronavirus.
It has the second highest case rate in Wales, with 54.7 cases per 100,000 people over the past seven days.
In Rhondda Cynon Taff, there were nine further coronavirus cases in the last 24 hours, making a total of 90 positive Covid-19 tests in the last week.
The situation there is "stable at the moment" according to council leader Andrew Morgan who said a full lockdown could be avoided as long as people followed the rules.
"Over the next week we can turn this round," he said.