So as to know our vulnerabilities and characteristics I'd guess. Once you know the genes you can use the vaccines and pharmaceuticals to manipulate the population however you want. Or so they think.
This understanding likely goes back to the origins of the Spanish flu which apparently started with a military vaccine experiment done by Rockefeller trained physician Dr. Frederick GATES.
Dr. Gates noticed that certain officers were apparently more likely to have severe vaccine reactions.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2126288/pdf/449.pdf