ESSENDON coach John Worsfold has expressed doubts over whether Conor McKenna ever had COVID-19 after the defender's negative test reading on Monday. 

McKenna became the first player to test positive to the illness on Saturday, following a low-grade irregularity in his test last Friday.

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However, tests earlier last week, and then again on Monday, showed the 24-year-old came back negative. He is due for more testing this week.

Worsfold, who is into his final season as Essendon coach, said the mix of results meant he wasn't sure McKenna had contracted the virus.   

"There's some doubt in my mind. I don't know if there's doubt in other people's minds but again we're waiting to find out exactly what it means," Worsfold said on Wednesday. 

"There's some pretty smart people out there who will assess what Conor's testing results are saying, but he's had a positive test with some negatives around that. 

"From my own personal point of view, if you said, 'Has he definitely got it?', I couldn't answer that. I would say that I couldn't say that he definitely has or he definitely hasn't." 

Victoria's chief health officer Brett Sutton said earlier on Wednesday morning that the dashing defender's test was being treated as a "confirmed positive".

"There are lots of people who test positive one day, they’re at the very tail-end of their infection and then they test negative the following day. If you get two negative tests 24 hours apart, you as a case are clear," he said.

"But your close contacts, [from] when you are potentially infectious, they have to go through their 14-day quarantine period. That will apply to Conor McKenna’s contacts."

Even with McKenna set to miss the game, Worsfold said the Bombers would be ready to face Carlton on Saturday night despite the interrupted preparation.

Essendon's players were able to a group indoor session via Zoom on Monday morning, and its coaches linked up online on Tuesday for a match committee meeting to start discussions about the Blues. 

Players – aside from McKenna and close contact James Stewart – were also cleared to train on their own outside on Tuesday evening to ensure they had some work in their legs after missing Sunday's postponed clash with Melbourne. 

They gathered back at Tullamarine on Wednesday for a lighter session before Thursday's main training session.  

Worsfold said he was unclear whether another negative test in the next 24 hours would see McKenna allowed back to the club in coming days.  

"I have no idea about what the outcome will be through government and AFL decision making. I couldn't even guess. I know what I'd like, but what it will be I really have no say on that at all," he said.

The Bombers remain unsure if McKenna will face a penalty for the AFL for any breaches of player COVID-19 rules. 

Worsfold said the club's groupings of nine players for non-full team sessions would continue to be mixed-and-matched. 

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"Our groups have changed weekly. We get the opportunity to change the groups after we get the results of tests back and those groups have changed multiple times over the last five or six weeks and they'll continue to change," he said.  

Essendon had started its season with two straight wins before the postponed game.

"We feel for them, but the players know we've got a game to play and they'll be excited about getting out there and representing the club really well," he said.