Colonizable planets will either: 1. be sterile, meaning that this is not a concern. (The only germs that settlers will run into are those they brought with the

Colonizable planets will either: 1. be sterile, meaning that this is not a concern. (The only germs that settlers will run into are those they brought with themselves on the ship.) 2. contain alien germs, in which case no humans would have antibodies for them regardless of origin or travel speed.