Ulster and Connacht can return to full rugby training on Monday after testing at both provinces earlier this week detected no cases of Covid-19.
Leinster and Munster have both been back since Monday last, observing strict protocols around gym equipment and training in pods of seven players.
They have not had access to dressing rooms, kitchens or video analysis rooms
Players and staff are having their temperatures checked daily with a contactless scanner.
- No positive results in first round of Covid-19 tests
- Pro14 to return in August with derbies behind closed doors
It has been almost four months since any of the provinces played a match and the Pro14 season has been abridged, with just two rounds of local derbies in each country now remaining.
Leinster and Munster will face each other at the Aviva Stadium in their first game back on 22 August with Ulster and Connacht squaring off in Dublin on the same weekend.
Ulster conclude their regular season campaign against Leinster a week later when Munster take on Connacht, again at the Aviva.
The top two in each Conference will then proceed to semi-finals on 5 September with the final on 12 September at a yet to be confirmed venue.
Leinster are already guaranteed to top Conference A while Ulster (A), Munster (B) and Edinburgh (B) are well placed to take the remaining three slots.
A statement from the Irish Rugby Football Union said: "The IRFU can confirm that the PCR testing of players and staff at Connacht and Ulster produced zero positive results. 118 players and staff were tested on Wednesday 24 June in Connacht and Ulster.
"The staff and players have been cleared to access their respective High Performance Centres from Monday 29 June."
To date there have been 258 tests conducted across the professional player and staff group and zero positive tests reported.
IRFU Medical Director Rod McLoughlin commented: "The first phase of PCR testing has been successfully completed. The players and staff now enter a period of daily medical screening and assessment. The second phase of testing will take place as players return to contact."