Top 5 stories on HIV in the US from CROI 2024

Professor Annie Luetkemeyer and Dr Hyman Scott, researchers on the doxyPEP studies, at CROI 2024. Photo by Liz Highleyman.
Professor Annie Luetkemeyer and Dr Hyman Scott, researchers on the doxyPEP studies, at CROI 2024. Photo by Liz Highleyman.

The Conference on Retroviruses and Opportunistic Infections (CROI 2024), took place earlier this month with research from around the world. Here is a roundup of research focused on the US.

Researchers from the US Centers for Disease Control and Prevention (CDC) presented data showing that the lifetime risk of acquiring HIV for Black gay and bisexual men in the US has decreased, from 1 in 2 in the period 2010 to 2014 to 1 in 3 from 2017 to 2021. There are still significant disparities between White and Black men, despite decreases in the numbers of new diagnoses for both groups.



The process by which cancer cells break away from where they first formed (primary tumour), travel through the blood or lymph system, and form new tumours in other parts of the body. The metastatic tumour is the same type of cancer as the primary tumour. 


An umbrella term for people whose gender identity and/or gender expression differs from the sex they were assigned at birth.


A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.


Chlamydia is a common sexually transmitted infection, caused by bacteria called Chlamydia trachomatis. Women can get chlamydia in the cervix, rectum, or throat. Men can get chlamydia in the urethra (inside the penis), rectum, or throat. Chlamydia is treated with antibiotics.


In a case-control study, a process to make the cases and the controls comparable with respect to extraneous factors. For example, each case is matched individually with a control subject on variables such as age, sex and HIV status. 

The use of HIV PrEP (regular medication to prevent HIV) in the US has increased steadily since it was first approved in 2012, with an estimated 363,957 people using it in 2022. Data presented at the conference showed that the number of new HIV diagnoses continued to drop steeply between 2012 and 2021 in US states with the highest coverage of PrEP.

However, there was an eightfold difference in annual changes to HIV diagnosis rates between states with high PrEP coverage (based on how many people need PrEP), when compared to those states with the lowest PrEP coverage. Access to PrEP through drug assistance programmes and state-level Medicaid expansion remains a crucial, central factor.

In Baltimore, Maryland, there has been a resurgence of hepatitis C among people who inject drugs in recent years, especially among people under 40. This is despite less injecting drug use, increased use of harm reduction services, and significant progress in reducing HIV transmission.

The research tracked changes in Baltimore over the past 30 years, focused on adults with a history of injection drug use. Comparing the period 2017-2019 to 1988-1992 shows a 98% reduction in the number of new HIV diagnoses overall. There was decline in HIV incidence from 4.1% in 1988 to 0.1% in recent years. However, between 2014 and 2019, hepatitis C incidence was 17% for people under 40, while remaining below 5% for older people.

At CROI 2024, aidsmap's Krishen Samuel spoke to Dr Manik Kohli from University College London about doxyPEP implementation and concerns about resistance.

Researchers presenting some of the earliest real-world data reported that taking the antibiotic doxycycline after sex (doxyPEP) appears to have lowered the incidence of sexually transmitted infections in San Francisco. DoxyPEP involves taking a single 200mg dose of doxycycline within 72 hours after sex. San Francisco was the first city to recommend doxyPEP, in October 2022, for gay and bisexual men and transgender people.

Among people who started doxyPEP at the San Francisco AIDS Foundation’s Magnet sexual health clinic, overall incidence of sexually transmitted infections fell from 18% to 8%, (a 58% decrease). Among those at the clinic who did not accept the offer of doxyPEP, incidence did not change much, falling from 8% to 7%. As in clinical trials of doxyPEP, the decrease was greater for chlamydia (a 67% decrease) and early syphilis (a 78% decrease) than for gonorrhoea (an 11% decrease that wasn’t statistically significant).

Results from a study of prostate cancer diagnoses and outcomes in the Veterans Aging Cohort Study were also presented at the conference. The Veterans Affairs healthcare system is the largest provider of HIV care in the US. Researchers matched men with HIV diagnosed with prostate cancer between 2001 and 2018 with at least two men without HIV who had been diagnosed with prostate cancer during the same period. Men with HIV had significantly higher levels of prostate-specific antigen (PSA) at diagnosis and a significantly higher proportion had metastatic cancer at diagnosis, indicating late diagnosis. However, there was no significant difference in the stage at which tumours were diagnosed when the Gleason score for each tumour was analysed (low-risk, intermediate or high-risk).