The World Health Organization said Monday that persuading people on the merits of a COVID-19 vaccine would be far more effective than trying to make the jabs mandatory.
The WHO said it would be down to individual countries as to how they want to conduct their vaccination campaigns against the coronavirus pandemic.
But the UN health agency insisted making it mandatory to get immunized against the disease would be the wrong road to take, adding there were examples in the past of mandating vaccines use only to see it backfire with greater opposition to them.
"I don't think that mandates are the direction to go in here, especially for these vaccines," Kate O'Brien, director of the WHO's immunization department, told a virtual news conference.
"It is a much better position to actually encourage and facilitate the vaccination without those kinds of requirements.
"I don't think we envision any countries creating a mandate for vaccination."
O'Brien said there may be certain hospital professions in which being vaccinated might be required or highly recommended for staff and patient safety.
But WHO experts admitted there was a battle to be fought to convince the general public to take the vaccines as they become available.
Only 'responsible' choice: Ryan
"The vaccine story is a good news story. It is the victory of human endeavor, potentially, over a microbial adversary," said the organization's emergencies director Michael Ryan.
"We need to convince people and we need to persuade."
As for making vaccines mandatory, he said: "I think all of us who work in public health would rather avoid that as a means for getting people vaccinated.
"We are much better served to present people with the data and the benefits and let people make up their own minds.
"There are certain circumstances... where I would believe that the only responsible thing would be to be vaccinated," he added.
According to the WHO's overview of different candidate vaccines, 51 have entered human trials, 13 of which have reached final-stage mass testing.
A further 163 candidate vaccines are being developed in laboratories with a view to eventual human testing.
The world-first roll-out of the Pfizer vaccine is due to begin in Britain on Tuesday.
As countries begin deploying vaccines in the coming weeks and months, WHO director-general Tedros Adhanom Ghebreyesus urged them to prioritize those most in need.
"These are not easy decisions," he said, setting out the WHO guidelines.
Tedros said health workers at high risk of infection were a top priority, plus people at the highest risk of serious disease or death due to their age -- thereby easing the pressure on health systems.
He said they should later be followed by people with a higher risk of severe disease due to underlying conditions, and marginalized groups at higher risk.
The WHO's ACT-Accelerator mechanism, pooling risk and reward among countries rich and poor, is a global attempt to speed up the development of COVID-19 vaccines, tests and treatments, and purchase and distribute them evenly regardless of wealth.
However, the scheme needs $4.3 billion urgently, with a further $23.9 billion required in 2021.
"What we need now globally is not to enter the land of empty promises in terms of supporting the ACT-Accelerator," said Ryan, urging wealthy donors to stump up.
"The means to do this allocation fairly and equitably is there. But what's not in place is the financing to make that happen in 2021.
"There's too much of a gap between the rhetoric and the reality."