St Johnstone have lost another two players to self-isolation rules ahead of their cinch Premiership encounter with Ross County on Wednesday night.
Chris Kane and Eetu Vertainen were already missing due to household Covid-19 infections and another two unnamed players have been hit by the same blow.
Davidson said: “We are going to be missing four players with the Covid rules and regulations. It’s really out of our control. I can ask the players to be as safe as they can be, but players’ wives work, people live with families.
“I’m not sure how to keep them safe and everybody available. They are testing every day now so it’s a really hard one for myself. I find it really frustrating.”