Conor McKenna is back at Essendon pressing his case for a senior call-up to face Collingwood this week, but coach John Worsfold says the Bombers need to be cautious of his fitness before he returns to the top level.

McKenna was earlier this week cleared to leave quarantine after testing negative to COVID-19 on multiple occasions following his positive test on Saturday, June 20.

That test saw the Bombers' game against Melbourne postponed. The Irishman was due to make his return to the field against the Demons, having been overlooked for their round two clash with Sydney.

It means the 24-year-old hasn't played a game at any level since March, with the Bombers conscious that he may benefit from a scratch match against the Pies this week instead of being brought straight in for Friday night's clash at the MCG.

"He feels great, he feels fresh. He's got no bruises, that's for sure. But the risk versus the reward of playing him after the period of time he's just had and what he's been able to do and what he can do in the next few days versus just getting him a hit-out," Worsfold said on Wednesday.

"We're weighing that up at the moment. We'll have a look at how he trains today, but there is definitely risk and reward there.

"He actually got in in the evening the other night and got to do a run around on his own, so he's already had one run and steps it up today."

The speedy half-back, who finished fourth in the Bombers' best and fairest last year, had already endured an interrupted season before his time in quarantine, having been back and forth to Ireland dealing with homesickness and during football's shutdown period.

Worsfold said the Bombers need to be mindful of the rate of injuries around the competition while acknowledging that McKenna's lead-in had been impacted.

"I'm very conscious of it. We've seen a number of soft-tissue injuries over the last couple of rounds, including some more collision or non soft-tissue injuries as well, which are often a sign that players haven't had the amount of time to prepare themselves for the nature of our game," he said.

"I wouldn't say I'm leaning towards being conservative [with McKenna], but I'm very conscious of rushing a player in and then potentially losing them for three or four weeks."

McKenna, who is contracted for 2021, has spoken of wanting to return to play Gaelic football in the next two seasons, but Worsfold said he isn't sure if the events of this season would make it difficult for the Bombers to keep the dashing backman.

"He's had a couple of false starts this year, but hopefully we can get him going as soon as possible and he can have a great, fun year," Worsfold said.

Essendon hasn't defeated Collingwood since Anzac Day 2017, and faces a tough task this week with star midfielder Zach Merrett suspended for his strike on Carlton's Jack Silvagni, which left the Blues forward hospitalised with a bruised lung and fractured rib.

"Zach understood there was a fairly serious injury that occurred out of his action, and AFL footballers these days understand, for the majority, they're accountable for that," Worsfold said.

"I don't think Zach's action was intentional or malicious, it was an action we see very regularly in the game. But if it causes an injury and it's not part of a tackle and part of the game, then you are facing some sort of sanction."