Awareness, Understanding and HIV Stigma in Response to Undetectable = Untransmittable Messages: Findings from a Nationally Representative Sample in the United Kingdom.

'Undetectable = Untransmittable', or 'U = U', is a message which communicates the scientific consensus that people living with HIV who maintain an undetectable viral load cannot sexually transmit HIV to others. This research aimed to empirically test whether a protection-framed U = U message is more effective at decreasing HIV stigma and increasing perceived accuracy of U = U than a risk-framed message. A nationally representative UK sample (N = 707) completed an online experiment. Participants viewed one of two U = U messages (protection-framed or risk-framed) and completed an online questionnaire. No evidence of a difference in HIV stigma at post-test or in perceived accuracy of U = U was found between the two message frame conditions. A minority of participants were aware of U = U prior to participation. Post-intervention, the majority of participants rated U = U as at least somewhat accurate. Higher understanding of U = U was associated with lower post-test stigma following a protection-framed message. Following a brief intervention, among a sample predominantly unaware of U = U previously, there was an overall favourable rating of U = U. No evidence was found for an effect of message framing on HIV stigma or perceived accuracy of U = U, but participants who completed a pre-test measure of stigma rated U = U as less accurate.