Anti-vaxxers try to hijack death of boxing legend Marvin Hagler, falsely claiming he died from vaccine side-effects

Anti-vaxxers have tried to hijack boxing legend Marvin Hagler's death after competitor Tommy Hearns said Mr Hagler was "in the ICU fighting after-effects of vaccine".

Hagler's family say that he died of natural causes at his home.

The 66-year-old was middleweight boxing champion between 1980 and 1987. Announcing his passing on Saturday, his wife Kay said his death was "unexpected". Hearns had said earlier the same day that Hagler was in intensive care fighting the side effects of vaccination, an unverified claim and something his family has made no mention of, The Daily Mail reported.

Hearns slammed anti-vaxxers for using the death of Hagler to further their agenda. No official cause of death has been announced. Hagler's son James told TMZ that his father was taken to hospital with chest pains and trouble breathing before he died about four hours later.

Hearns wrote on Instagram earlier on Saturday: "He’s in ICU fighting the after-effects of the vaccine! He’ll be just fine but we could use the positive energy and Prayer for his Full Recovery!"

Anti-vaxxers then argued on social media that Hagler's death proved that vaccines are unsafe. Hearns wrote on Instagram on Saturday evening: "Our love and respect to Marvin and his family, this is not an anti-vaccine campaign... it's outrageous to have that in mind during the passing of a King, Legend, Father, Husband and so much more."

Kay Hagler wrote on Facebook: "I am sorry to make a very sad announcement. Today unfortunately my beloved husband Marvelous Marvin passed away unexpectedly at his home here in New Hampshire. Our family requests that you respect our privacy during this difficult time."

Read more: Marvin Hagler death: Boxing legend dies aged 66

Over 100 million doses have already been administered in the United States, according to CBS News, with over 35 million Americans being fully vaccinated.

Progress is being slowed by vaccine-hesitancy, with 35 per cent of African Americans not planning on getting the vaccine according to a poll from the Kaiser Family Foundation, NPR reported in January.

Over a third of Republicans also say they don't want the vaccine, according to a CBS News poll.

The Centers for Disease Control and Prevention says the vaccines are "safe and effective" and that severe side effects are extremely rare.

Still, anti-vaxxers jumped on news of Hagler's death to push their unsubstantiated narrative.

Hagler, who legally changed his name to Marvelous Marvin Hagler, fought 67 times over 14 years as a pro, retiring at 34 after losing to Sugar Ray Leonard, a decision he claimed was stolen by the judges, the Associated Press writes.

Hagler beat Hearns in a fight in 1985 that is legendary in boxing circles.

Hagler won 62 out of his 67 games, 52 on knockouts.

He once said: "If they cut my bald head open, they will find one big boxing glove. That's all I am. I live it.''