Doxy PEP at AIDS 2026: The Evidence Is Growing. Access Must Follow.

Doxy PEP at AIDS 2026: The Evidence Is Growing. Access Must Follow.

Doxy PEP at AIDS 2026: The Evidence Is Growing. Access Must Follow.

By Leandro A. Mena, MD, MPH, FIDSA, Chief Medical Officer, NMAC

As an infectious diseases physician and NMAC’s Chief Medical Officer, one of my priorities is helping translate scientific advances into information and services that communities can actually use. Few topics at AIDS 2026 in Rio de Janeiro made that responsibility feel as immediate as doxycycline postexposure prophylaxis, commonly called doxy PEP.

When the World Health Organization issued its first recommendation on doxy PEP earlier this year, many of us had the same question: would the results seen in clinical trials hold up in routine practice? I left Rio encouraged. The evidence is holding up. I also left convinced that the true impact of doxy PEP will depend on whether we build systems that make it accessible, trusted, and responsibly monitored.

Researchers presented findings from Australia, Brazil, Taiwan, the United States, the Dominican Republic, Canada, and New Zealand. The settings were different, but the message was consistent. Doxy PEP is reducing syphilis and chlamydia. Gonorrhea remains more complicated. And access continues to reflect the same inequities that shape HIV and STI outcomes more broadly.

The evidence is holding up

The strongest population level evidence came from Australia. Researchers analyzed data from 25 clinics that included more than 83,000 gay and bisexual men. After national guidance was introduced, syphilis diagnoses were 46.5 percent lower and chlamydia diagnoses were 27.2 percent lower than projected from earlier trends. Gonorrhea did not decline.

A study from a North Carolina HIV and PrEP clinic showed a similar pattern in a region with a high STI burden. Among 219 people prescribed doxy PEP, STI case positivity decreased from 8.2 percent before initiation to 3.9 percent afterward. The largest reductions were seen for chlamydia and syphilis, with a smaller reduction in gonorrhea.

Figure 1. Real world effectiveness of doxy PEP in a Southern U.S. HIV and PrEP clinic. Source: Niehaus ED et al. “Real world effectiveness of doxycycline postexposure prophylaxis for STI prevention in a Southern U.S. HIV and PrEP clinic.” AIDS 2026, abstract OAC4205. Graphic prepared from data presented at AIDS 2026.

Figure 1. Real world effectiveness of doxy PEP in a Southern U.S. HIV and PrEP clinic.
Source: Niehaus ED et al. “Real world effectiveness of doxycycline postexposure prophylaxis for STI prevention in a Southern U.S. HIV and PrEP clinic.” AIDS 2026, abstract OAC4205. Graphic prepared from data presented at AIDS 2026.

For those of us working in the Southern United States, these findings matter. Communities across the South carry a disproportionate burden of HIV and STIs while also facing persistent barriers to sexual health services. New prevention tools can make a difference, but only when people can reach them and feel safe using them.

A modeling study from Brazil added an important antimicrobial stewardship perspective. Offering doxy PEP after a new STI diagnosis, rather than universally to everyone receiving HIV PrEP, was projected to prevent about 44 percent of STIs while reducing related antibiotic use by 58 percent. This supports a targeted approach, but not a rigid one. Decisions should also reflect changing circumstances, individual preferences, relationships, and sexual networks.

Figure 2. Modeled tradeoffs between broader doxy PEP coverage, STIs prevented, and antibiotic use in Brazil.

Figure 2. Modeled tradeoffs between broader doxy PEP coverage, STIs prevented, and antibiotic use in Brazil.
Source: Torres da Silva MS et al. “Impact of doxy PEP on sexually transmitted infection diagnoses and antibiotic use among men who have sex with men and transgender women on PrEP in Brazil: a modelling study.” AIDS 2026, abstract OAC4202. Graphic prepared from data presented at AIDS 2026.

Researchers also presented early findings on daily doxycycline preexposure prophylaxis, or doxy PrEP. The results were promising, but the studies were small. Larger trials are needed to understand effectiveness, tolerability, toxicity, resistance, and the implications of longer antibiotic exposure.

Access will determine who benefits

The presentations from Taiwan and the Dominican Republic illustrated how differently access can look. In Taiwan, half of nearly 1,500 gay and bisexual men surveyed had heard of doxy PEP, and 46 percent said they were willing to use it. Many also wanted access outside hospitals and clinics through pharmacies, community drop in centers, and online platforms.

Figure 3. Awareness, willingness to use, and prior use of doxy PEP among gay and bisexual men who have sex with men in Taiwan.

Figure 3. Awareness, willingness to use, and prior use of doxy PEP among gay and bisexual men who have sex with men in Taiwan.
Source: Ku SWW et al. “Uptake of postexposure prophylaxis with doxycycline and preferred access to STI testing and doxy PEP among gay and bisexual men who have sex with men in Taiwan: 2025 HEART survey.” AIDS 2026, abstract OAC4204. Figure adapted from the AIDS 2026 presentation.

In the Dominican Republic, only 7.9 percent of men who have sex with men, transgender women, and female sex workers surveyed through HIV self testing programs had heard of doxy PEP. Yet almost nine in ten of those who were aware believed it was effective. That is not simply hesitancy. It is a gap in information, counseling, and service delivery. Integrating doxy PEP education into HIV self testing and PrEP programs could help close it.

The New Zealand studies added another lesson. Awareness and use were lowest among men who had sex with both men and women. Men in nonmonogamous relationships who reported only one recent partner were also less likely to know about or use doxy PEP, even when their partner had other partners and their STI exposure remained substantial.

These findings remind us that sexual health cannot be reduced to a checklist or a partner count. People live within relationships and sexual networks. Eligibility criteria that are too narrow can miss those who may benefit, especially people who do not see themselves reflected in traditional sexual health messages or who may not feel comfortable sharing all aspects of their sexual lives.

Services must meet people where they are

At NMAC, we have long understood that having an effective intervention is not the same as having equitable access to it. People need choices in how and where they receive care.

In Philadelphia, the PHASES project brought together public health, academic, pharmacy, and community partners to provide HIV testing, PrEP, PEP, and doxy PEP through community pharmacies. In Florianópolis, Brazil, a municipal program integrated doxy PEP into PrEP services through telehealth. People completed online screening, received an assessment through WhatsApp, obtained an electronic prescription, and collected medication near their home.

The Brazilian program also detected asymptomatic STIs and connected people who had been using doxycycline on their own with accurate guidance and monitoring. These models will not fit every setting, and they do not need to. Their importance is that they were designed around the realities of the people they intended to serve.

We cannot separate access from responsible monitoring

The weaker and less consistent effect of doxy PEP on gonorrhea remains an important concern. It likely reflects, at least in part, differences in tetracycline resistance across settings. Responsible implementation requires monitoring resistance patterns, prescribing practices, medication use, and possible effects on organisms beyond the STIs doxy PEP is intended to prevent.

But calls for surveillance must be accompanied by investment. In many parts of the world, STIs are still managed syndromically because reliable laboratory testing is unavailable, unaffordable, or too slow. Syndromic management has an important role where diagnostic options are limited, but it misses many asymptomatic infections and makes it difficult to know which infections are circulating or whether resistance is changing.

We cannot ask countries to monitor antimicrobial resistance without supporting the systems needed to do it. Governments, donors, manufacturers, and global health agencies should invest in affordable etiologic diagnosis, molecular testing, gonococcal culture and susceptibility testing, specimen transport, trained laboratory personnel, and linked clinical and public health data.

Surveillance must also be transparent and developed with communities. It should improve care and guide responsible implementation. It should never become another reason to stigmatize, blame, or deny services to communities already carrying a disproportionate burden of HIV and STIs.

From evidence to action

I left Rio optimistic. Doxy PEP is delivering meaningful benefits outside clinical trials, especially against syphilis and chlamydia. We now have an opportunity to move from evidence to impact.

For NMAC, that means helping the HIV and STI workforce understand the science while keeping community needs at the center. It means supporting shared decision making, culturally responsive education, routine STI testing, and services that are accessible in the places where people live. It also means advocating for the diagnostic capacity and public health infrastructure needed to use this tool responsibly.

Science has given us another important option. Our responsibility is to make sure it does not become available only to those who already have the easiest path to care. Doxy PEP can strengthen STI prevention, but its promise will be fulfilled only when access, equity, trust, and community leadership are treated as essential parts of the intervention.