Islatravir, the first nucleoside reverse transcriptase translocation inhibitor, plus Pifeltro (doravirine) kept viral load suppressed for  48 weeks, with only a small number of people experiencing treatment failure. Islatravir halts construction of new viral DNA and also acts at a later step in the viral replication process. Previously untreated participants in a Phase II clinical trial were randomized to take islatravir plus Pifeltro and lamivudine or the Delstrigo single tablet-regimen. Those who achieved viral suppression dropped lamivudine and stayed on the two-drug regimen. At 48 weeks, 90% of people taking islatravir plus Pifeltro and 84% of those taking Delstrigo had an undetectable viral load. Four participants taking the islatravir regimen and one person taking Delstrigo experienced viral rebound, and one islatravir recipient never achieved full viral suppression. In all cases, viral load remained below 100. A viral load below 200 was not considered clinically significant, and people with a viral load this low do not transmit HIV through sex.