Steve Clarke claims he has experienced the most "disruptive" time of his Scotland tenure ahead of the World Cup qualifying triple-header.
Midfielders Scott McTominay and Stuart Armstrong were already ruled out of the matches against Denmark, Moldova and Austria and they were joined by injured Celtic duo James Forrest and Greg Taylor, who both missed the Hoops' 1-0 defeat by Rangers at Ibrox on Sunday.
Rangers right-back Nathan Patterson, along with Aston Villa's John McGinn, who has tested positive for Covid-19, are currently following government guidelines and will not be available for the match against Denmark.
Boss Clarke revealed that set-piece coach Austin MacPhee, who he had just been added to his backroom staff, "has picked up Covid" and will miss the three games, with Hearts coach and former Scotland attacker Steven Naismith drafted in to help.
Clarke said: "Probably two years into my international career it has probably been the most disruptive camp in terms of call-offs, which is disappointing.
"But I think I have enough in the current group to go to Denmark and hopefully get the result we all want.
"Medical advice and information tells me that both John and Nathan should join us after the Denmark game, which is good, so I don't have to delve too deep for replacements.
"I will work with a slightly smaller squad for the Denmark game and hope to welcome the two boys back on Thursday morning.
"Everyone who is in the squad is fit and available.
"Stephen O'Donnell was not involved at the weekend but was available to be involved, he did a training session yesterday and felt good and will be ready for Wednesday night.
"I don't expect any more issues, that's not to say there won't be any more issues.
"Covid has been with us for a long time now, it seems like forever.
"It is what it is, we deal with it, I am sure other nations are having similar problems.
"We will deal with whatever it throws at us and we will get a team on the pitch who will be very competitive."
On MacPhee's absence, Clarke explained: "It is a completely different blow for me.
"I was hoping I would have a new coaching team in place, at the very last minute I asked Steven Naismith – who I know as a player – to step up and become an extra pair of eyes on the training pitch. He will be here for this camp."
