All athletes and entrants for the 2022 Boston Marathon must be fully vaccinated against COVID-19 ©Getty Images

All athletes and entrants for next year's Boston Marathon will need to be fully vaccinated against COVID-19 in order to participate in the race, organisers have announced.

The policy brings the annual event in line with other major sports competitions in the United States, which have made vaccines mandatory in response to the COVID-19 crisis.

The Boston Athletic Association (BAA) said it had set the field size at 30,000 for the 2022 edition of the race, scheduled for April 18.

Participants must be able to show proof of being fully vaccinated prior to picking up their bib on April 15.

Organisers have warned those who try to participate without vaccination proof will not be able to take part and their entries "will not be deferred, refunded, or transferred to a future race".

BAA President and chief executive Tom Grilk said the organisation "want to do our part to continue to mitigate the spread of COVID-19 as we continue our return to racing".

"As we look to return to the traditional Patriots’ Day date for the first time since 2019 and allow for as many athletes to participate as safely as possible, we know that a fully vaccinated field is the appropriate requirement to implement," Grilk said.

Organisers of the 2022 race have revealed the field will be set at 30,000 ©Getty Images
Organisers of the 2022 race have revealed the field will be set at 30,000 ©Getty Images

Grilk last month revealed 93 per cent of participants in this year's race, held on October 11, were fully vaccinated.

Of the remaining seven per cent, he said 0.3 per cent tested positive for COVID-19 which disqualified them from the race, although they will have their entry fee refunded.

The number of participants permitted at the 125th Boston Marathon was reduced by more than a third to 20,000.

The United States has been the country worst affected by COVID-19, with nearly 47 million cases and more than 768,000 deaths recorded.

According to latest figures, the US has fully vaccinated 58 per cent of its population.

The Boston Marathon in Massachusetts is the world's longest-running annual marathon, but the in-person event was cancelled for the first time in its history last year because of the pandemic, with a virtual alternative running instead.

It is usually held on the third Monday of April, but this date was delayed until October 2021.

Kenya's Benson Kipruto triumphed in the men's race, while his compatriot Diana Kipyogei won the women's event.