Political and business leaders in the north-west have called on residents to comply with new restrictions announced at Stormont on Thursday.
They also accepted, however, that the rules could hit the local economy hard.
SDLP leader Colum Eastwood said that following the regulations could save the lives of friends, family and neighbours.
"Everyone has made immense personal sacrifices to keep themselves and their families safe," the Foyle MP added.
"People have lost mothers and fathers, brothers and sisters to this virus and have given up the chance to say a proper goodbye in many cases.
"People in the north-west have been very good at following the public health advice, even when it appeared confusing.
"But if we're honest, the cautious attitude we all took at the start has slipped.
"People aren't always wearing face masks in shops, unnecessary journeys have become routine again and compliance is not as good as it should be.
"The hard truth is that unless people change their behaviour immediately, we're going to lose more friends, neighbours and family members.
"These restrictions will be challenging.
"People in our communities are naturally sociable, entrepreneurial and active.
"But they (the rules) are absolutely necessary to relieve pressure on our health service and protect each other.
"Derry and Strabane has shown that it can step up when needed.
"It is now needed again and I know that people will do all that they can."
Colin Neill, chief executive of Hospitality Ulster said: "This will come as a shock but no surprise to the hospitality sector in the north-west, which has experienced the worst impact of this for over six months now.
"Public health and control of the coronavirus is the number one priority.
"But it will, without doubt, be a devastating blow to our sector at this critical time."
The Federation of Small Business described the restrictions as disappointing.
It also called on the Government to bring forward a support package for firms.
News of the tightening of restrictions in the Derry and Strabane council area came as it was learned that the city's Halloween festival was to be scaled back because of the health crisis, with the fireworks display scrapped entirely.
The annual event brings more than 100,000 people into the city every year and generates business worth more than £3m for local firms.
Foyle MLA Sinead McLaughlin said the cancellation of the fireworks was a major blow to the city and its economy.
"It's a very important festival, an important economic festival for the city and for all of its businesses," the SDLP woman told this newspaper.
"But at this moment in time, it is the right decision that the council has made.
"Every single hotel bed in the city is normally occupied over the Halloween period.
"It has a significant impact upon our hospitality and tourism sector, in particular, and also within retail.
"It is a blow, but it's a blow that has been made with safety in mind."
Derry and Strabane Mayor Brian Tierney said that while it was disappointing to have to scale back the festival, the council's decision was "a responsible and proportionate response to the current health situation".