Holmes said he will also cover for Alison Hammond who misses Monday’s show due to “sickness”.
Kay had been set to join the line-up for three days alongside regular guest host Rochelle Humes before Phillip Schofield and Holly Willoughby return from their summer break.
Holmes, who has been anchoring the show over the summer with Ruth Langsford, tweeted on Sunday: “Just when u thought you’d got rid of me…sickness with @AlisonHammond and @vernonkay means I’m off the bench.
“Get well soon to them but I have my boots on and I’m ready to play. Monday and Tues line up is now myself and @RochelleHumes. Hope you can join us.”
In an interview with The Sun, Kay said he had tested positive for Covid.
He told the newspaper: “I’m absolutely gutted that because of a positive Covid test I’m no longer able to present on This Morning next week with Rochelle nor do Radio 2 guest hosting and Steve Wright’s cover, two iconic shows which I’ve been a fan of for decades.”
Kay was originally due to be hosting Tuesday, Wednesday and Thursday. It is not yet clear if he will still be hosting on Wednesday or Thursday.
Humes was also due to reunite with Hammond on Friday, but it is not known if Hammond will be able to return.
Hammond has not publicly commented on her illness.
Regular Friday co-host Dermot O’Leary is hosting parts of Friday’s show live from Manchester where he will be based in preparation for charity football match Soccer Aid.