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Introduction: Recent research has shown high efficacy of HIV treatment for reducing the risk of HIV transmission to sexual partners. As the efficacy of treatment as prevention (TasP) has proliferated, a new messaging campaign, Undetectable = Untransmittable, has been gaining popularity. The purpose of this paper was to assess factors associated with the perceived accuracy of this TasP messaging strategy among a large and diverse sample of gay, bisexual, and other men who have sex with men (GBMSM) in order to inform subsequent efforts at large-scale and implementation of the HIV prevention message.

Methods: We conducted a nationwide survey of GBMSM in the U.S. recruited from an online social networking site and a mobile sexual networking app. We analysed data from 12,222 GBMSM separately by HIV status to examine sociodemographic and behavioural factors associated with ratings of the accuracy of the Undetectable = Untransmittable message, which included the option to indicate not understanding what “undetectable” meant.

Results: Among HIV-negative and unknown men, multivariable linear regression indicated that being on pre-exposure prophylaxis (PrEP), identifying as gay or queer (versus bisexual or straight), recent serodiscordant condomless anal sex (CAS), testing every six months or more often, less concern about sexually transmitted infection (STI) infection, and lower perceived risk of HIV infection were the factors with the largest independent effect on rating the Undetectable = Untransmittable statement as more accurate. Fewer factors emerged as associated with accuracy ratings among HIV-positive participants—reporting an undetectable viral load, a lifetime acquired immune deficiency syndrome (AIDS) diagnosis, and lower concern about STI infection were the factors most strongly associated with rating the statement as more accurate.

Conclusions: The findings of the current study highlight variability in the perceived accuracy of the Undetectable = Untransmittable message, suggesting potential subgroups who might benefit from targeted educational campaigns, perhaps broadcast utilizing sexual networking apps. Numerous factors, particularly among HIV-negative and unknown GBMSM, were associated with rating the message as more accurate. In particular, being on PrEP and testing regularly were two of the variables most strongly associated with higher accuracy ratings among HIV-negative GBMSM, suggesting HIV prevention services as potential points of intervention for increasing HIV knowledge and decreasing HIV stigma.


This article was originally published in the Journal of the International AIDS Society, available at

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial License.



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