There's a very, very great incentive to develop a vaccine when the companies know that if it is developed within a year, as they will start receiving return on that investment within a year. That relatively short time frame effectively guarantees that for a novel virus, it will still be present, thus maximizing profits.
If the Fed doesn't relax the rules, the companies have far less of an incentive to develop a vaccine. The normal 4-5 year development to distribution means maximum investment up front, with minimum return in the end, because the virus will likely be a non-factor in 4-5 years, based on prior pandemics.