They won't be forced to have flu shots to play and have forced the ARL Commission to change the NRL's tack.

The Raiders trio were allowed to train on Thursday, having originally been forced to sit out Wednesday, pending the ARLC's meeting.

They'd objected to some of the wording of the initial waiver and crossed it out before signing it on Tuesday.

It reportedly stated they were at greater risk of catching influenza if they didn't have the injection and is believed to be the same wording that Gold Coast Titans utility Bryce Cartwright objected to.

Raiders chief executive Don Furner was yet to see the reworded waiver, but hoped his three players would be free to continue training on Friday.

"They just have to sign a revised waiver. I haven't seen it yet, so they're working on it," he said.

"So we're hopeful. I'm sure it will be resolved when we get the wording through tonight. Just a last-minute hiccup. Just one of the many challenges.

"They trained [Thursday] and I'm confident they'll be training [Friday]."

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The trio received the backing of top sports doctor Peter Larkins, who said players shouldn't be forced to have flu injections to play.

It would be a different story if there was a vaccine for the COVID-19 virus.

Larkins felt the NRL could find themselves in court if they had tried to force the players.

"I think there'd be a significant backlash from any player who was excluded from playing. I think his manager and lawyers would be jumping all over the NRL if they excluded somebody for not having the flu vaccine," Larkins said.

"I think it would be different if there was a corona vaccine - and there isn't - I think that would be a stronger argument to enforce that so it didn't stop the competition."

The NRL said 97 per cent of all players and staff on the Apollo register had been vaccinated.

Each club is permitted 32 players and 18 staff on the register, and they're all covered by the NRL's strict biosecurity measures.

That means up to 24 players and staff across the NRL haven't had the flu injection and were forced to sign waivers instead.

The NRL also announced there would be no easing of restrictions for Mother's Day.

"The protocols allow for exemptions to vaccinations under compelling circumstances, including requiring players to sign a release," the NRL said in a statement.

"Until an NRL-approved release is acknowledged and signed by players, they will not be permitted to train."