Mom2Sofie&Twins is right - it is standard in the US and so that's why we gave it to our son as well. Yes, a side effect of the vaccine (and with others too) is that you might come down with a slight fever for a few days after, but that's normal and our son was actually fine.
When living in HK you are in the virus capital of the world. Our doctor strongly recommended us getting it as it can be fatal in some cases with babies.
My helper got it as well.