Let's look at the risks associated with the Dtap shot, according to the CDC's list of side effects. Keep in mind, this is just one jab on a long list of jabs.
25% of babies get a fever.
25% of babies get redness or swelling
25% of babies get soreness or tenderness
Other mild problems include:
Fussiness (up to about 1 child in 3 (33%)
Tiredness or poor appetite (up to about 1 child in 10)
Vomiting (up to about 1 child in 50)
that's 7 rolls of the dice that essentially gives you odds your baby is going to suffer more than 1 'mild' side effect. I've seen my friend's babies after they come home from the hospital. It doesn't seem mild when you baby is crying, won't nap and won't breastfeed. Doctor's recommend a pain-reliever for these mild symptoms... and the drug remedies begin in infantsy-- further win for the pharmaceutical industry. Big Pharma has a new life-long client.
Moderate Problems (Uncommon)
Seizure (jerking or staring) (about 1 child out of 14,000)
Non-stop crying, for 3 hours or more (up to about 1 child out of 1,000)
High fever, 105 degrees Fahrenheit or higher (about 1 child out of 16,000)
Sometimes the 4th or 5th dose of DTaP vaccine is followed by swelling of the entire arm or leg in which the shot was given, for 1 to 7 days (up to about 1 child in 30).
that's 3 more rolls of the dice at low odds, but those few unlucky babies don't care about odds, twitching around or running a life-threatening fever.
extremely remote side effects include seizure, coma and low consciousness.
Of course, these are just the side effects that are confirmed. Reasonable minds will conclude that some effects exist but are not proven. That's just common sense.
So, that gives you an idea about the math involved. Do with it what you will.