On my book, there are rules that all humans that leave earth or go to a new planet need to have the necessary biological upgrades to survive alien vessels, worlds, and cosmic issues that go hand-in-hand with space travel and exploration. It's not safe out there and all precautions are made as a result and new laws put into motion,
As a result, anti-vaxxers (for an example) and those who don't have their vaccines aren't allowed off-planet for their own safety and safety of others and aliens alike; human illness can be just as deadly as aliens even if the human isn't affected; they're considered a carrier for either someone else or the next generation (this is only background information; not important to the story itself)
So, when space fairing is more common, everyone is inoculated; more often than not it's always short term and so they have to have jabs more often, especially those working in an exploration or military organization in space.
Now, to get to the topic, Earth gets destroyed and the humans that remaining and survived to go to their new planet; but it's still an alien world they'd have to live long term so the remaining organization develops new technology to enable permanent changes into the human immune system (and other biological systems) that enable their survival.
I know there's a lot to consider in terms of deadly space diseases; such as radiation, pathogens, alien contact, including sexual contact (because....well that really shouldn't surprise anyone). No one wants alien STDs (or STIs) so they have ways to deal with that;
So my solution to survive all the crap would be a genetic-alteration to the human DNA through drugs (for the whole first generation) so that the mutations and anti-bodies from the drugs would be passed down from one generation to the next without the need of more as they live on their new homeworld; this would cause their immune system to adapt to that as if it was their true homeworld.
This would cause significant cost cuts in the long run once the first generation or so pass on their mutations so they wouldn't have to keep occulting the entire human population every year against their new world (standard jabs are still required as usual).
But my question is, would this actually be a viable solution to their problems for the long-term plan or would they still need to incorporate more through tactics (such as implants, other means of genetic modifications or breeding programs)?