GILLON McLachlan says the AFL is working through whether Essendon defender Conor McKenna breached any COVID-19 protocols, but has shut down the "wild theories" relating to the Bomber's positive test.

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McKenna has tested negative to the illness twice this week since his positive reading was detected last Saturday, which saw the Bombers' clash with Melbourne postponed.

The League's chief executive said he expected McKenna and teammate James Stewart – who was deemed a close contact of the Irishman last week at training – to be forced to complete their full 14-day isolation periods despite the subsequent negative readings.

"To clear a few things up, and because (McKenna's) swabs from the 19th and 20th, which were the Friday and the Saturday, were re-tested and he was positive on those days," McLachlan said on 3AW radio on Friday.

"And on that basis, he and James Stewart as a close contact will go through a 14-day quarantine.

"He's been negative twice since. The virology was very low, so it’s a very low rate.

"And then he's had some serology for bloods done since, and he has antibodies. I know I'm probably giving a lot of detail there, but I think it's important to straighten this up."

McLachlan said the AFL and health officials would be further investigating the 24-year-old's positive test, which was the first for the AFL since players returned to training in May.

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"There is chance that it was from some time ago, and there is some level of remnants in his system at very low levels," he said.

"We'll do further blood testing and blood work. But he definitely was positive and he’ll go through 14 days. His close contacts have been isolated and that’s what we know today.

"Whether it was from an illness in Ireland or other, that’s for the medical people to continue to work through, and maybe we won’t have certainty on it."

McKenna visited multiple home inspections and saw his host family last week and the AFL on Friday met to discuss whether he had breached any COVID-19 protocols.

"There's a meeting on that this morning. What I'd say again [is] there's wild theories and everything that are going around," McLachlan said.

"I think it's accepted that he went to some public real estate openings and to his host family. Both of those breaches are marginal. The theory that his behaviour was risky… none of that is proven to be true."