No life-form on Earth either lives or dies in vain. Because the fact that you die from some virus removes your gene-pool from what remains on the Earth, so that those who did not die from it have the immunity to it allowing them to continue forward. So you didn’t die in vain and you didn’t live in vain. And that process that continued for millions of years, in the evolutionary tract of the tree of life on Earth, has created what is today a portfolio of living organisms that have survived this far. And we’ve got germs within us that are not killing us, that would have killed earlier versions of us, but we survived it. Now you bring aliens down, they don’t have those millions of years of naturally selected immunity, from our diseases. This is what happened when Columbus crossed the Atlantic.
Neil deGrasse Tyson