Vaccines, sure. I think you may misunderstand how insurance works. It's a risk pool. It exists so if you have a heart attack, you don't have to shell out $500,000 for treatment. That $500,000 is spread over all the people who MIGHT have a heart attack. Basically, you trade the low probability of a high expense for the certainty of a low expense. The insurance co. doesn't collect $500,000, they collect more to cover their own costs and profit. Everybody's happy.
Now, how does that work for things like vaccines, where there's a 100% chance of you getting them? Yup. No risk pooling. You pay the cost, plus the insurance company's costs, plus their profit, minus whatever discount they can negotiate as a big company, if they care to because you're ultimately paying for it anyway. Blood transfusions, not so much. I've never needed one, so I infer the risk is low. I'd rather pool that risk and pay a couple bucks a year because hey, maybe I'll need one someday. The years I don't, that money can pay for someone else's.
Birth control isn't much different. You have a high likelihood of needing an inexpensive thing. The cost is just tucked away in your premium where you won't notice it, you'll just be ticked off (again) that your premiums are so high, and wonder why they can't control costs better.