I suppose it depends on how their biology came to be. Diseases evolved here based on the the general structure of the species that existed around them. It could be that they are so different that nothing we have here interacts with them.
I would also assume that if they’re intelligent enough to create the means to get here that they would also be intelligent enough to have considered this problem and would have some sort of containment mechanism for themselves.
That’s assuming their biology is in any way compatible with ours.
They’d probably need something equivalent to an EVA suit just to survive in our environment either way.
If aliens did visit earth we would probably see them more like the Vorlons in babylon 5, in they would never be able to leave their suits.
This is how we defeated the Martians.
Most viruses and bacteria have to adapt and specialize to their host. An alien life form will most likely be immune and vice versa.
Humanity has many kinds of dangers for unwary aliens
Wouldn’t it be tragic if aliens came to make contact and start a friendship with us…only to be laid low by COVID, which for us is like a bad flu, but for them ended up being more like ebola?
Oof.
I think it’s a safe bet that an alien race that has figured out FTL and how to identity inhabited planets has also figured out germ theory even if they somehow had a biology similar enough to us to be at risk in the first place.
We were pretty careful with the apollo astronauts when they returned to earth on the off chance some dangerous space virus survived on the moon. https://spacecenter.org/apollo-mission-quarantine-procedures/
Hope you don’t mind. But everyone who is reading this read the spacecenter.org the guy or gal linked its a good read. Thank you sir or mam
