The 57-year-old’s 10-day self-isolation period came to an end on Thursday after he and two players tested positive prior to the Carabao Cup match against Hull last week.
But his return has been put on hold with assistant manager Alan Irvine, who has been in charge for the last three matches, set to be on touchline duty again at the King Power Stadium.
Irvine said: “He’s OK. I spoke to him this morning but he’s not been in as we hoped he might have been.
“He’s feeling OK but at the moment we are just following all the guidelines and protocols. He’s in contact with the medical people at the club, obviously, and the Premier League.
“It’s been deemed that it is not right for him to come in just yet so we’ll take it day by day.
“Clearly this is an illness that affects people very severely. It is a very serious thing, I don’t think anybody quite knows what the full effects are and I don’t think it is consistent – it is different from one person to another.
“So it is vitally important that we are safe and follow the protocols that are in place. We need to think about the safety of everybody else at the football club.
“At this moment I would think that it is more likely he won’t be on the touchline at Leicester but that can change during the course of the day today and then tomorrow, so we will carry on the way that we have been trying to work in his absence.
“He may not be here in person but he continues to be involved in what we do and is making the final decisions with everything we are doing. That will continue whether he is on the touchline or not.”
Irvine oversaw the Hammers’ first Premier League win of the season, 4-0 against Wolves, last weekend, but the Scot laughed off suggestions Moyes should stay away more often.
“I definitely don’t think he should do that! We need him back as quickly as possible,” he added.
“The manager is one of the key people at any club and the rest of us can try to relay his messages when he’s not around but the only way to get them nailed down, exactly how he wants, is to deliver them himself.
“Getting him back as quickly as possible is important but it has to be right for him and everybody else at the club. These are very difficult times.”
Issa Diop and Josh Cullen, who also tested positive, are back at the club’s Rush Green training ground.