IDK if it ever became a right (except for Medicare), but it became a requirement to pay to have health care coverage with the Affordable Health Care Act or pay not to.
It's like Social Security for retirement, also not required before it was enacted...and now it's accepted and expected. Required to pay in, accepted that you do and expected to be paid out during retirement. You can only opt out by not collecting benefits, but you still need to pay in by law.
The same fits about the AHA now are very similar to what happened when Social Security was enacted. Attempted repeals went on for years.