The Sydney Morning Herald said the Raiders - beaten by the Roosters in last year's grand final - told them not to train. It reported they could be sidelined for the season if they maintain the stance, which involved crossing out a line on an NRL legal waiver.
That part of the document asks players to acknowledge they face more chance of getting the 'flu without an injection. Australian Prime Minister Scott Morrison, a Cronulla supporter, has already entered the debate with a "no job no play" call.
The Titans' Bryce Cartwright has a similar stance based on right-to-choose, although he objects strongly to being labelled an anti-vaxxer.
But it seems while Cartwright might be stood down, players with religious-based objections could be given dispensations. Any exemptions will be made case-by-case.
Veteran league journalist Paul Kent, a host of Fox League NRL 360, says their refusal is religion related.
"There's some players apparently at the Raiders today who trained separately from the rest of the group because they are of Polynesian heritage and their religion says they can't get the flu shot, they're not allowed to do that," Kent said.
"The NRL is likely to allow those players to continue because of their religious convictions but if it's just a moral viewpoint like Bryce Cartwright you'll simply be told you're not playing.
"The fact is the NRL is doing everything to lower the percentage of risk so that means take the flu shot because that will help.
"Religious viewpoints are different to ethical viewpoints and that's why the ethical deniers will simply be told 'you don't have to take the needle, you're not forced to take the needle, but you will not play NRL this season."
ARL Commission chairman Peter V'landys is to talk with the Rugby League Players Association about encouraging players to take the flu shots before the NRL kicks off again on May 28.
Papalii has been identified as a "committed Christian" as one report put it.
News.com reported: "The league's biosecurity measures allow for anti-vaxxer players to be eligible for selection with the signing off of a waiver — but the game was reportedly considering closing the waiver loophole for anti-vax players after Prime Minister Scott Morrison earlier called for a no jab, no play stance."
League icon Phil Gould told Channel Nine the flu vaccination was an accepted part of the game, and he had never seen it raised as an issue before.
He said waivers were standard practice.
"Now for the player who says 'I don't want to be vaccinated', the league says, 'well OK, you need to sign an indemnity here,' I don't know what can come from that, the worst he can get is the flu I suppose," Gould said.
"That's a personal choice and I don't want to get into the whole anti-vax argument, that's a whole other debate. And I don't think it's a big deal, it just happened around the time when people were looking for a story."
