Healthcare staff at Ysbyty Gwynedd are taking part in a UK-wide trial which aims to find out if those who have previously contracted coronavirus, have immunity from future infection.
The trial, named SIREN, is being led by Public Health England and around 130 different sites are taking part.
Early reports from the study indicate that antibodies from past Covid infection provide 83% protection from contracting the virus again for at least five months.
More than 100 healthcare workers, including doctors, nurses, healthcare assistants and administrative staff, at the hospital in Bangor have been recruited for the trial.
Participants will at first be tested every two weeks, with both a blood sample and nasal or throat swab, to see if they have contracted the virus. The tests will also be analysed to see whether or not they have developed antibodies.
The study follows participants for a year so that researchers can monitor how long immunity may last.
Consultant Physician Dr Chris Subbe is leading the study at Ysbyty Gwynedd and is also taking part himself.
Dr Subbe said: "Siren is set to answer one of the most important if not the most important question for COVID-19: Does infection protect from future illness and if yes for how long?
"When 100s of front-line workers have suffered COVID-infection as part of their work for the NHS we need to know how this will affect our abilities to care during coming pandemics with similar viruses."
Caroline Mulvaney-Jones, Clinical Research Specialist Officer for Health and Care Research Wales, based at Ysbyty Gwynedd, said: “The Research Team are very proud and excited to be part of this trial, we have had a superb response from the staff at the hospital who have signed up to be part of this vital research.
“A lot of the participants feel as though they are giving something back and as they are getting tested on a regular basis it also gives them peace of mind.
“It’s been really interesting to see the mixture of different healthcare workers coming forward to be part of this, from admin staff to Consultants – the uptake has been fantastic.”
Latest data shows that more than 1,657,028 people in Wales have already been offered some protection from coronavirus by receiving their first vaccine dose.
The rollout has progressed to offering the jab to adults over the age of 40 after the top nine priority groups were contacted by early April.