Both first grade and under 20s sides were forced into lockdown last night, along with all associated staff, after Hunt tested positive for regular influenza, despite earlier immunisation.

Five of his teammates - Darren Lockyer, Sam Thaiday, Justin Hodges, Peter Wallace and Israel Folau - were this morning cleared of the H1N1 strain. The club is not expected to find out Hunt's swine flu result until later this afternoon, casting serious doubt over Friday's game at Suncorp Stadium.

"He had to do a further test because Karmichael was positive for influenza and because all the boys have flu injections at the start of the season they felt it was really strange that he would show positive to influenza," Broncos CES Bruno Cullen told ABC radio this morning.

"That led them to believe there was a strong possibility that he might have swine flu. Because of that, they did further tests and we're awaiting the results."

Cullen said the entire club was in lockdown and would have to remain quarantined for 72 hours if the result came back positive. That would rule out the top-of-the-table clash with the Canterbury Bulldogs on Friday night.

"The whole team is in quarantine right now. Our best advice (yesterday) was to get on the front foot and assume that the test would come up as positive and because of that, anyone who had had association...with Karmichael Hunt over that period should be in isolation.

"At the moment we have about 50-odd people in isolation - the total NRL squad, the total Under 20 squad and all associated staff.

"It really does put our match into doubt."

The entire group had been given a course of Tamiflu anti-viral drugs.

Mr Cullen assured fans would be given refunds if the game was cancelled.

The news comes as the number of people infected with swine flu in Queensland swelled to 58 overnight, with five more cases of H1N1 virus confirmed.