Why are rna hiv tests not recommended for screening? are therefore susceptible to false positives? do they become more accurate after a month? some hiv foundations like san francisco aids foundation use them. thank you for the info in advance?

CDC.gov has good discussion. Could not cover well n 400 spaces. You can also google pubmed.gov & search for RNAI HIV tests AND screening in exactly that format & can find the worlds lit to review yourself for a more detailed review. Another option (I think is the best) is to get a one month subscription to uptodate.com and read the best reviews of this topic. U can learn everything $20 I think.

RNA tests are more accurate but more expensive. Antibody tests are generally used for screening and RNA tests for confirmation. There is no scientific reason to not use RNA for screening. Visit this site for info: HIV test window periods https://www.cdc.gov/hiv/basics/hiv-testing/test-types.html

In addition to Dr. Grim's excellent reply: Test approval for a particular use requires the producer to apply to FDA with data justifying that use. The HIV RNA blood tests were developed and initially approved only to monitor HIV status. Although often used for diagnosis of new infection, about a year ago one manufacturer applied and received FDA approval for diagnostic use.