Children of staff at a virus-hit chicken factory have been told to stay home and self-isolate until the end of the month.
All 900 workers at the 2 Sisters plant in Coupar Angus were sent into quarantine after an outbreak earlier this week.
Now the Scottish Government has tightened restrictions, ordering anyone living in a household with a factory worker – including young family members – to also isolate.
First Minister Nicola Sturgeon confirmed the new measures after the number of positive cases connected to the plant rose to 43.
Of those affected, 37 are factory workers and six are their contacts.
Each person has reported mild symptoms and none have required medical care.
A manager at the plant tested positive for the virus on Friday, after he contracted it from a close family member.
Bosses took the decision on Sunday night to close down the factory, when the number of cases began to rise.
All employees, who usually travel to work from across Tayside, were told to self-isolate at home until August 31, even if they have tested negative.
They have told they can only leave their homes to get tested.
Employees have even been advised not to go out for food or medicine, but to order it online or ask someone to deliver it to their home.
Perth and Kinross Council has been working to encourage all staff to get tested, with information packs made available in Bulgarian, Polish and Romanian.
It is understood that a third of the workforce has already been checked.
The military set up a mobile testing unit in the grounds of the factory, and Dundee City Council confirmed another testing site would be available for factory workers only at Blackness Road Fire Station.
The walk-through station will open from early afternoon, and no appointments are necessary.
Announcing further restrictions for worker’s households on Thursday night, Dr Emma Fletcher, Associate Director of Public Health at NHS Tayside said: “This is a critical change to our advice.
“We are putting place this extra measure to help prevent further spread of infection in the community.”
An URGENT change in advice has been issued by our partners at NHS Tayside, Perth & Kinross Council and Public Health…
She said: “It is also really important that everyone in the Tayside area is extra vigilant in the FACTS guidance, in particular the over 70s, and those who are shielding or in high-risk groups.
“A large proportion of the workforce has already come forward for testing, which is excellent but we would strongly encourage all workers who have not yet been tested to take up this offer, even if they don’t have any symptoms.”
Dr Fletcher added: “We continue to work closely with the factory and local authority colleagues to ensure that all workers have the right information and support to access testing.”
During First Ministers’ Questions, Ms Sturgeon described the cluster as “significant” and said new measures were being considered.
Scotland registered 77 new cases new laboratory-confirmed cases of Covid-19 overnight, the highest number in almost three months, and Ms Sturgeon confirmed 27 of these had been recorded in the NHS Tayside health board area.
The first minister said the number of cases linked to the Coupar Angus outbreak will “almost certainly grow” and she stressed the importance of testing all workers.
“Given the nature and potential scale of this outbreak, we are considering carefully and urgently whether further restrictions are necessary,” she added.
Local MSP and Deputy First Minister John Swinney said appropriate action was being taken to stop the spread of the virus.
“The extra measures put in place aim to protect workers, their families and the community at large,” he said. “It is therefore vital that the new guidance is closely followed.
“This news will be difficult to process for those that are affected, and many families will be worried about the economic consequences of being required to self-isolate until the end of the month.
“To that end, it is imperative that those isolating receive the appropriate financial support during this period.”