A total of 12 matches have now been called off in the past two weeks as Britain battles record numbers of positive Covid cases due to the Omicron variant of the virus.
Earlier this week Premier League clubs rejected the option of temporarily halting the season to allow a circuit breaker for infections.
However, the traditional Boxing Day schedule of fixtures has already been disrupted with the potential for more to go in the coming days with daily testing now in place for English top flight clubs.
“Following postponement requests from Leeds United and Watford as a result of COVID-19, the Premier League Board met this morning and regrettably agreed to call off the two affected clubs’ Boxing Day fixtures,” the Premier League said in a statement.
Leeds reported five positive cases among players and staff on Thursday which allied to a lengthy injury list meant they would be unable to field a team with the required 13 outfield players and one goalkeeper from their registered 25-man squad.
Watford’s previous two matches against Burnley and Crystal Palace had also been called off.
However, the league said it expected their fixture with West Ham on December 28 to go ahead due to players coming out of isolation.
The Premier League revealed this week that only 84 percent of players have had at least one dose of vaccination.
Leeds are among the clubs with the highest uptake of vaccines in the league.
“All of the cases we have experienced are asymptomatic which we believe is due to our high vaccine take up,” Leeds said in a statement.
“The positive cases, combined with our well documented injury issues, means that we would not have enough recognised first-team players to meet the Premier League requirements for the fixture.
“The training ground at Thorp Arch will be closed for a period of two days on the advice of Public Health England.”
No restrictions have yet been put in place for the size of crowds at matches in England, although supporters do have to provide proof of vaccination or a negative test taken in the previous 48 hours.
Sport in Wales will be forced back behind closed doors from December 26, while in Scotland a restriction of 500 for outdoor public events from the same day has seen Scottish Premiership clubs bring forward their winter break by a week.