A second construction site in Dublin has been shut down after a worker connected to the first site tested positive for Covid-19.
John Sisk & Son confirmed it had halted building work at the East Quad site in Grangegorman to allow for a deep clean.
The company was notified late on Wednesday afternoon that an employee had contracted coronavirus.
A spokesperson for John Sisk & Son said 240 people were working on site and the HSE is implementing testing for them.
However, Acting Chief Medical Officer Ronan Glynn said there hadn't been an outbreak.
He said it was his understanding that the employee is connected to a separate site on Townsend Street, which had to be closed down earlier this week due to a cluster of Covid-19 cases.
Dr Glynn confirmed there are now between 25 and 30 positive cases connected to that site, but added that there hasn't been a "substantial increase".
Two new buildings to accommodate students at Technology University Dublin are being built on the site which was forced to close yesterday.
The project is a joint venture between John Sisk & Son and Spanish firm FCC Construction.
There has only been one confirmed case linked to the site.
In a statement, John Sisk & Son said: "We have temporarily closed that site in order to facilitate a deep cleaning of all the facilities on site and the site itself.
"The site has followed the specific advice of the HSE and the Health and Safety Authority at all times since the commencement of the Covid crisis.
"We are liaising with the HSE and the other relevant bodies in how we manage this incident.
"The health, safety and well-being of those who work with us and the communities in which we operate is our top priority.
"We are liaising directly with the staff member's employer, one of our subcontractors, with regards to his welfare and well-being and we wish him a speedy recovery."
Siptu construction sector organiser John Regan said the developer "acted very quickly", in following procedures properly and he hoped the site would return to operation soon.
It comes after another company, John Paul Construction, had a site on Townsend Street temporarily closed by the HSE on Monday after more than 20 of its building workers contracted coronavirus.
There are now between 25 and 30 confirmed cases linked to the site, but the outbreak has been described as "under control".
"In relation to the first site, it is between 25 and 30 cases, so it hasn't increased substantially, but 30 cases in one area is substantial and demonstrates how quickly this virus can spread," Dr Glynn said. "There is robust guidance in terms of returning to the workplace and as workplaces open back up clusters are going to be inevitable."
Up to 200 employees were working on the site, which is being developed for a 393-bedroom hotel, a 202-aparthotel, a restaurant and 21 apartments.
John Paul Construction said it is assisting the HSE in arranging further tests for workers and the site remains closed.
"The site will remain closed until they get the advice to reopen," a spokesperson for the company said.
"As people have been sent home and the site is closed they don't have a true sense of cases.
"This is really in the hands of the HSE."
Labour councillor Kevin Donoghue had called for testing to be made available for residents and shop workers in the area who may have come into contact with building workers.
John Paul Construction has carried out a number of prominent construction projects involving hotels, including Adare Manor in Limerick and the Morgan in Dublin.