I've read that vaccines made from aborted fetal tissue cause the adverse reactions. Since embryonic stem cells come from aborted babies, do they have any harmful effects?

I've read that vaccines made from aborted fetal tissue cause the adverse reactions.

Yes, that's true. But there are other ingredients which also cause adverse reactions. I'm sure you would have seen the vaccines thread which remains on the first page of New Posts

Since embryonic stem cells come from aborted babies, do they have any harmful effects?

The embryo (baby) is killed to get the stem cells. This is murder!

Embryonic cells are not only a physical risk and danger to the recipient. If one  receives embryonic cells knowing that another human being was killed in order to attain them, then that is very grave sin.

Much safer and more effective are your own cells. It is a long time still I studied this but there are ways of using your own cells or other moral sources.