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Nobel laureates are among scientists calling for volunteers to be exposed to coronavirus after receiving a vaccine to see if it offers protection.
In an open letter to the head of the US National Institutes of Health, the group says so-called "challenge trials" could accelerate vaccine development.
The Oxford University Covid-19 vaccine programme's director said such studies should be "feasible and informative".
There are now 23 coronavirus vaccines in clinical trials around the world.
The only way we will know if any of them works is if enough volunteers are subsequently exposed to coronavirus in their daily life, and don't get infected.
That could take well into next year, given that many studies are being conducted in countries where infection rates are falling.
The organisation 1 Day Sooner, consisting of more than 100 prominent figures including 15 Nobel laureates, argues this should not be left to chance.
It wants healthy young volunteers to be deliberately given coronavirus after receiving the vaccine, arguing that the risks to their health would be low, but the potential benefits to society enormous.
The letter states: "If challenge trials can safely and effectively speed the vaccine development process, then there is a formidable presumption in favour of their use, which would require a very compelling ethical justification to overcome."
The letter supporting challenge trials has been signed by Professor Adrian Hill, the director of the Jenner Institute at Oxford University which has one of the leading prototype coronavirus vaccines.
He said human challenge studies could happen "in the coming months".
Dr Francis Collins, director of the NIH, has said Covid-19 challenge trials are "on the table for discussion - not on the table to start designing a plan".
