I don't know your specific situation but I followed an LPR's process to get the green card and it involved a rigorous health exam, including vision, thorax, immunology, vaccines and who knows what else.

The price was in the hundreds of dollars in a somewhat poor country.

The doctor was very clear that he could have been refused because of the results he never saw.

It's speculated that STDs are also tested, but as I wrote, he never saw the test results.