Essendon coach John Worsfold says he is uncertain whether quarantined defender Conor McKenna actually has COVID-19 but maintains his confidence in the strict testing regimes in place for AFL clubs.

McKenna tested negative to the coronavirus several times before an irregular result last Friday led him to being re-tested on Saturday, with that result coming back positive.

He has since been in quarantine and returned a negative test, which was confirmed on Tuesday night.

McKenna is still being treated as a positive case by Victoria’s Department of Health and Human Services.

“There’s some doubt in my mind,” Worsfold told reporters on Wednesday.

“I don’t know if there’s doubt in other people’s minds but we’re waiting to find out exactly what it (the latest negative result) means.

“There’s some pretty smart people out there that will assess what Conor’s testing results are saying.

“He’s had a positive test with some negatives around that, so from my own personal point of view … I couldn’t say he definitely has (the virus) or he definitely hasn’t.”

A DHHS investigation found Bombers teammate James Stewart was a “close contact” of McKenna, forcing the fringe forward into quarantine.

The decision on Stewart being the only extra player required to self-isolate was a relief to Essendon amid fears at one point their entire backline might be put out of action.

Last week’s game against Melbourne was postponed indefinitely just 24 hours before it was due to be played, but Worsfold said the build-up to Saturday night’s meeting with Carlton would be relatively “normal” for the unbeaten Bombers (2-0).

“We have to deal with what’s in front of us and we know this is just a weird season, so this has not thrown the players out too much because they’ve been through a lot over the last 12 weeks,” Worsfold said.

“We want to get out there and train really well tomorrow to keep building on the game plan that we’ve been working on over the whole summer and leading into this season.

“We’ve only played it twice and we’ve got a lot of improvement to go.”

Worsfold said Essendon had been rotating players through different combinations in their small training groups and would continue to do so.

He could not say whether Essendon would attempt to get McKenna out of quarantine following the latest negative test.

Essendon speedster Orazio Fantasia will be put through a thorough fitness test at training on Thursday in his bid to return from a quadriceps strain.