The World Anti-Doping Agency (WADA) has clarified that there is "no reason to believe" COVID-19 vaccines would break anti-doping rules.
"The health of athletes is the primary concern of WADA during this pandemic and they can rest assured that in the highly unlikely event that a vaccine may cause a possible anti-doping rule violation under the World Anti-Doping Code, WADA’s oversight of any subsequent results management will ensure that vaccines and the principles of anti-doping do not come into conflict," the global anti-doping watchdog said.
"To be clear, despite the novelty of these vaccines, there is no reason to believe such vaccines would contravene anti-doping rules."
WADA's statement comes after one from a senior UK Anti-Doping (UKAD) official attracted criticism from some athletes - despite saying it was "extremely unlikely" the vaccines could violate anti-doping regulations.
Nick Wojek, UKAD head of science and medicine, had earlier said the organisation was awaiting progress updates from WADA.
"WADA is currently liaising with pharmaceutical companies and the International Federation of Pharmaceutical Manufacturers and Associations (IFPMA) to determine whether the constituents of the vaccines in development are prohibited in sport, and whether the technologies being used will pose any complications for detecting doping," Wojek said.
"We are in regular contact with WADA to obtain progress updates.
"Whilst it is too early to make a definitive statement on any particular vaccine, WADA has already confirmed that it is extremely unlikely that the RNA or DNA sequences used for such vaccines violate anti-doping regulations.
"Equally, the risk that the excipients used for such vaccines will pose issues for clean sport and the anti-doping regulations is anticipated to be small.
"We await further updates from WADA on the matter before being able to advise athletes on the anti-doping status of any specific vaccine.”
The statement has attracted criticism from some athletes, including seven-time Para-swimming world champion Tully Kearney.
"I’m actually shocked being in the ‘clinically extremely vulnerable’ group and likely to be called for vaccination soon that this has not been dealt with sooner," Kearney wrote.
"So do I risk potential serious illness/death from COVID or a doping ban and miss out on going to Tokyo?!?!"
WADA's statement should allay the fears of Kearney and others.
The United Kingdom began a rollout of a coronavirus vaccine earlier this week, after UK regulators became the first to approve the use of the Pfizer-BioNTech vaccine.
Around 800,000 doses of the vaccine are expected to be dispensed in the coming weeks.
Residents in a care home for older adults and their carers are listed as the top priority for vaccines in the UK.
People over 80 years of age, frontline health and social care workers are listed as the second priority.
Clinically vulnerable Paralympians are likely to be offered the vaccine soon as the UK works through its priority list.