This is incorrect. In Bruesewitz v. Wyeth, the supreme court ruled that The National Childhood Vaccine Injury Act of 1986 protected vaccine manufacturers from being sued over "unavoidable, adverse side effects". For example, you can sue if a vaccine manufacturer screws up and replaces your vaccine with poison. You can not sue because you think that the vaccine has caused your child's seizures.

I don't believe, at any point, the supreme court has ever examined whether or not vaccines are safe. The ruling here was only about what kind of cases manufacturers were liable to be sued, and it was determined that "vaccines caused my child seizures" was not such a case.

You can read more here https://www.supremecourt.gov/opinions/10pdf/09-152.pdf