Assume virology, vaccine technology, etc. are all valid and reasonable approaches (just for shits and giggles).
People used to make vaccine products by producing or cloning them in some type of animal model. At first that meant cows, goats, etc.
Then that moved into things like e-coli bacteria, splicing in some RNA into the bacterial plasmid (genetic info), so the bacteria then produces the protein.
Now, probably to save steps and money, pharma uses normie's genetic code to produce the protein of interest.
DNA produces Messenger RNA (mRNA), which is just a work-instruction for a protein.
The Messenger RNA gets sent to the cell where a protein is create based on the code.
I've been through failure analysis of big fuck ups, sometimes it's due to multiple things fucking up in a single locus in almost a 'perfect storm', sometimes it's a concept that was so stupid most people didn't understand how stupid it was. /rant