Per my understanding.
It's approval (and then mass production) that takes a while, and as others have posted if it's similar to an existing vaccine that can be expedited.
In all seriousness, the mRNA vaccine technology is starting to get into Star Trek realm. In several episodes the crew encounters a new virus and the doctor whips up an antivenom/etc to counter the virus. This is likely to become a similar technology. As others have also mentioned, an obvious target is the flu, since we can adjust the vaccine so much more quickly, and the efficacy of this vaccine will likely continue to be much more effective. Other viruses should prove likewise treatable. Cancers also a possibility.
And that helped in developing the COVID-19 vaccine so quickly. mRNA is the future of vaccine development and it is approaching Star TREK realm. With companies like Moderna and Repligen we are going to make some major advances in the near future
"Before there was ever a COVID-19 pandemic, our ten years of research and clinical trials taught us valuable lessons about designing both mRNA therapeutics and mRNA vaccines. This includes, in particular, how to manufacture and formulate mRNA that can produce the targeted proteins – the spike protein, in the case of coronaviruses like the SARS-CoV-2 virus – in the body. Clinical trials of our mRNA vaccine candidates against a variety of viruses have repeatedly demonstrated that they induce the desired immune response.
By the time of the COVID-19 pandemic, we had already been working for years on vaccines for infectious diseases, including on other coronaviruses and their spike proteins. As part of our mRNA technology platform, we had also already developed an mRNA delivery system that was specifically designed for vaccines.
Once the COVID-19 pandemic struck, we were well positioned to adapt our existing mRNA technology to try to address the global public health crisis. We worked closely with the NIH and other government and non-government partners to design and implement a robust COVID-19 vaccine clinical trial program that prioritized safety. Our speed in developing the Moderna COVID-19 vaccine was ultimately a product of our many years of research and investment in mRNA vaccines."
Pfizer and Moderna had alpha and beta versions but the vaccines protected people well enough that it didn’t become a problem. They are already testing a delta varient case. The FDA has promised a flu vaccine like quick approval, provided the mRNA is nearly similar (and it will be.)
To update the vaccine.
Then it would just be a production issue of how quickly they can manufacture, which given they've produced over 1.5 billion doses so far in 2021, is pretty fast.
The FDA process - one would hope it is similar to the flu vaccine, which is updated every year to account for different strains. Each year's vaccine does not have to undergo a new FDA approval.
It could be revolutionary though.
bound to be a nice business for them!