Howling:Crash Of The Byzantium

In the episode " Crash Of The Byzantium" - River gives Amy an injection of some sort, with the excuse that it is to protect her from any possible germs/virus on the alien planet. But why, in all the episodes and planets I've seen, very very rarely is anyone worried about ambient virus infections. Is this just a way of bringing the characters together to talk, or is it a definate way of taking something from or adding something to Amy's dna/blood?

It could be that she was checking to see if amy was pregnant ... or it could be that they knew the Byzantium was leaking radiation. Besides that it could be anything Cory Jaynes 19:55, August 3, 2011 (UTC)