It's a very new recommendation, and I know there have been pertussis outbreaks, but if you search the world health organization, you will see that pertussis never went away. It has been on the rise steadily for the last 20 years. You are not at any new risk to develop it than you were 5 or 10 years ago. Personally, I would not inject anything like that (or the flu shot) while pregnant. I no longer vaccinate, so please consider that with my opinion; however, even when I was "pro-vaccine" I opted out of the flu shot during my pregnancy. Good luck!
"Whenever you find yourself on the side of the majority, it is time to pause and reflect." ~Mark Twain