The situation is expected to become worse in the coming days.
The latest figures from the Garda Representative Association (GRA) mean that more than 1,100 gardaí have become unavailable to work since mid-December.
At that stage there was 90pc of the garda force available.
The drop in available numbers is believed to be largely related to members self-isolating either due to contracting Covid or being a close contact with an infected person.
An Garda Síochána has now been provided with 30,000 antigen tests and it is expected another 70,000 will be made available in the coming weeks.
This was brought in after garda members expressed dissatisfaction with having to buy large numbers of test kits for themselves.
GRA interim general secretary Philip McAnenly said that while it welcomes "the sudden availability of these antigen tests, it feels like we are slamming the door after the horse has already bolted".
"In early 2021 we called for priority vaccinations for our frontline members in both their interests and for the safety of the public, but we were refused," he said.
"We have been demanding priority booster vaccinations and access to priority PCR testing, but again, our calls have been ignored.
"Now it seems Garda management has only been prompted into action by the predicted and recent surge in Covid cases.
"There are now over 1,100 less gardaí available for duty than just over two weeks ago and we believe that many of these cases could have been avoided had a proper and appropriate booster vaccination and PCR testing scheme been made available.
"Our members have done extraordinary work protecting the public during the pandemic, often at great risk to their own personal health and to that of their families, in the best interests of the public.
"Yet it seems that Garda management's answer is to try to exempt gardaí from the requirement to self-isolate."
An emergency meeting was due to be held today between Director of Human Resources (Garda Civilian HR Directorate) Yvonne Cooke and senior executives of the Garda unions, to discuss the issue.
The news comes as many other emergency services are grappling with the significant impact of the Omicron variant on staffing levels across the country.
Dublin Fire Brigade has said that up to 15pc of its emergency crews were not able to work over Christmas. This is because they contracted Covid or were self-isolating.
"Dublin Fire Brigade has seen an increasing negative impact on staffing levels," said a spokesman for Dublin City Council, which oversees the operation of the fire brigade service.
"Rising positive case numbers and increasing numbers self-isolating or awaiting tests has resulted in up to 15pc of staff directly impacted."
Last Thursday the National Ambulance Service (NAS) sent out messages asking for any available staff to work overtime and to cover up to 19 staff who were out sick.