Wales' Six Nations match at home to Scotland on Saturday has been postponed because of the coronavirus outbreak.
The two other round five scheduled games had already been postponed and no date has been confirmed to complete the 2020 Championship.
The Welsh Rugby Union had insisted earlier on Friday the game would "go ahead as planned".
But now the match has become the latest sporting event to fall foul of the coronavirus outbreak.
Several sports have been severely disrupted, with all Premier League and EFL football matches suspended until 3 April.
A WRU statement read: "The Welsh Rugby Union has maintained an open dialogue with, and continued to seek advice and direction from, the National Assembly for Wales and other stakeholders, including the Six Nations, on this fast-moving issue.
"Whilst medical advice remains consistent, we have decided that it is in the best interests of supporters, players and staff to fall in line with recent measures taken across the UK and global sports industries.
"The WRU would like to thank all parties for their counsel on the subject and will make further announcements with respect to rescheduling the fixture in the coming days.
"Every effort has been made to stage this game and we appreciate that individuals will have been inconvenienced. Given the fluid and unprecedented nature of this issue a postponement became the only viable option."
Friday's Under-20 Six Nations match between Wales and Scotland in Colwyn Bay will go ahead but will be played behind closed doors.
It has been an unprecedented day of widespread sporting postponements worldwide.