I can confirm that you can get a little sick from the second round vaccination. Fever, headache... yeah. Been there...
This is a good thing, mind you. This is your immune system reacting the way it's supposed to react. And it only lasts one day - a little tired the next day, but symptoms gone. But it wasn't a very pleasant day.
Don't let it deter you. One day with a low-grade fever and a headache (which, in my case at least, both responded to acetaminophen - advil) beats the heck out of a serious respiratory infection.