Construction is continuing through Level 5 restrictions as the hospital is considered an essential public project.
BAM has introduced weekly testing for all 1,000 workers on site.
The developer expects the measure to identify positive cases before symptoms appear, in an effort to reduce the risk of transmission among workers.
The company is using saliva PCR testing with a turnaround time of 12 hours.
Anyone who tests positive is being sent home and asked to arrange an official HSE Covid-19 test.
BAM trialed the new testing regime last week on 336 workers, detecting six cases who had no symptoms.
The weekly serial testing of the full site, commenced this week and will be undertaken for a minimum of six weeks before being reviewed.