A third of US health department websites don’t mention U=U

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While almost all state health department websites in the US provide information about PrEP, 18 do not mention ‘Undetectable equals Untransmittable’ (U=U) by name. Even when U=U is covered, there are gaps in the information provided on many of these official websites.


Undetectable = Untransmittable (U=U)

U=U stands for Undetectable = Untransmittable. It means that when a person living with HIV is on regular treatment that lowers the amount of virus in their body to undetectable levels, there is zero risk of passing on HIV to their partners. The low level of virus is described as an undetectable viral load. 

post-exposure prophylaxis (PEP)

A month-long course of antiretroviral medicines taken after exposure or possible exposure to HIV, to reduce the risk of acquiring HIV.


A healthcare professional’s recommendation that a person sees another medical specialist or service.

virological suppression

Halting of the function or replication of a virus. In HIV, optimal viral suppression is measured as the reduction of viral load (HIV RNA) to undetectable levels and is the goal of antiretroviral therapy.

“State health department websites serve as a free and trusted resource for health professionals and community members to access health information,” write researchers from George Washington University. In February 2022, they systematically analysed HIV prevention information provided on the websites of health departments in each of the 50 states, plus the District of Columbia.

Overall, 33 of the websites explicitly mentioned U=U, although another nine did provide links to external websites where U=U was covered. More state websites covered PrEP (46) and PEP (42).

The accuracy of information on U=U was evaluated based on four criteria:

  • 27 states indicated zero transmission risk
  • 29 states said this applied to sexual transmission specifically, meaning that it could not be misinterpreted as applying to injection or other risks
  • 30 states referred to a person whose viral load was undetectable or suppressed
  • 24 states mentioned that viral suppression needed to be sustained across time (e.g. for at least six months, ‘durably’ suppressed, etc).

Only 18 state websites (just over a third) were accurate in relation to all four criteria. There were 17 state websites which included misleading or ambiguous language (e.g. ‘virtually no risk’, ‘minimal risk’, ‘effectively no risk’).


Etami Y et al. Accuracy of HIV Risk-Related Information and Inclusion of Undetectable = Untransmittable, Pre-Exposure Prophylaxis, and Post-Exposure Prophylaxis on US Health Department Websites. AIDS Patient Care and STDs 37: 425-427, 2023.