This probably deserves its own thread but....It has already happened:

US Army Creates Single Vaccine Against All COVID & SARS Variants, Researchers Say


Within weeks, Walter Reed researchers expect to announce that human trials show success against Omicron—and even future strains.
TARA COPP | DECEMBER 21, 2021
CORONAVIRUS ARMY CIVILIANS

Updated on Dec. 22 to add information from Walter Reed officials about testing the vaccine against the Omicron variant.

Within weeks, scientists at the Walter Reed Army Institute of Research expect to announce that they have developed a vaccine that is effective against COVID-19 and all its variants, even Omicron, as well as previous SARS-origin viruses that have killed millions of people worldwide.

The achievement is the result of almost two years of work on the virus. The Army lab received its first DNA sequencing of the COVID-19 virus in early 2020. Very early on, Walter Reed’s infectious diseases branch decided to focus on making a vaccine that would work against not just the existing strain but all of its potential variants as well.

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