Any vaccine they come up with will only work half the time.
Cold and flu vaccines are for the old and weak.
The low efficacy of 'flu shots' is largely due to it being a vaccine against the most virulent strains for the particular flu season, and because failure is generally measured as 'did you get a flu-like illness?'
It doesn't 'prevent the flu' if you get a different strain of the flu, or say a coronavirus with flu-like symptoms, nor is it counted as 'successful' in efficacy rates if you are sick for only a couple days instead of a week or longer.
Flu shots reduce the chances of getting sick from the strains of influenza they immunize for, and even if you do get sick, the length and severity of sickness is likely to be significantly reduced. It's more
important for vulnerable populations because it might be fatal for them, while someone in otherwise good health with a strong immune system will almost always survive. Importantly for the community if not for the individual, the contagious period is also reduced for those viruses you're immunized against.
If you find skipping half the flus you would otherwise catch and diminishing the severity of the rest an attractive proposition, then a flu shot is something you might want to consider.
The rate of efficacy of a theoretical Wuhan coronavirus vaccine isn't known, but as a vaccine against a single strain it ought to be substantially more effective than an average flu shot. While no vaccine has ever been 100% effective, if we write off every treatment in medicine that has a less than 100% effectiveness there would be nothing left.