Details obtained by the Irish Examiner under Freedom of Information confirmed that, between January 2008 and December 2010, a total of 52,667 HSE applications were sent to the Garda Central Vetting Unit (GCVU). Of these, 44,033 were sent for vetting.
The HSE has confirmed that 163 people were barred from taking posts because of a previous conviction or non-conviction deemed serious enough to be a potential threat to vulnerable members of the public.
A request for a breakdown of where these individuals were due to work, as well as the reasons why they were barred, was refused.
Anyone who is due to take up public service work that involves working with children or vulnerable people must submit to background examinations by the GCVU, which consists of 77 civilians and six gardaí.
However, the HSE has admitted it was unclear if some private agency workers temporarily employed in public hospitals to plug gaps in the workforce had undergone garda checks before working.
It has also claimed details of the number of staff who failed checks but continued to work are not available.
However, the need for a robust vetting process was underlined last year when Prime Time found some private nursing homes do not ensure their staff are vetted before working with vulnerable elderly people.
Last June, then Fine Gael education spokesman Brian Hayes — now Minister of State for Public Service Reform — said the garda vetting unit should be exempt from the recruitment ban to ensure suspect applicants were picked up.