Vaccine Regret

When my son was born last week I denied the hepatitis b vaccine at the hospital because from what I’ve researched you can only contract the disease through mother if she is positive for it, sex with positive carriers, dirty needles or blood/saliva from hep b positive people. I was tested during pregnancy for hepatitis and am negative and my baby will obviously not come into contact with the other ways of getting the disease. This is why I denied it. Then at his first pediatrician appointment they asked me if i got the vaccine in the hospital to which i said no. They basically said it’s required for school or daycare entry so it would be best to do it now so he has the three doses by that time. I have no idea why but I agreed to it. Now I’m feeling deep regret and have been very emotional for going through with it without fully looking into the pros/cons first. I just don’t want anything to negatively affect my precious baby that is less than a week old. I didn’t even have the hep b vaccine until I was eight. Why are they giving this to infants? Someone please help calm my nerves about this... 😥