HIV Vaccine Awareness Day 2025: Where Does the Science Stand?

Every year on May 18, scientists and health groups mark HIV Vaccine Awareness Day. The day honours the volunteers and researchers working on an HIV vaccine. After more than 40 years of research, there is still no licensed vaccine. But new science gives reasons for cautious hope.

HIV Vaccine Awareness Day was started in 1997 by the US National Institutes of Health (NIH). Clinics like Whitman-Walker Health in Washington D.C. use the day to recruit trial volunteers. The message in 2025 is clear: progress is real, but slow.

Why an HIV vaccine is so hard to make

HIV is unlike most viruses. It changes its surface fast. It hides inside the immune cells that should fight it. And it builds a permanent reservoir in the body within days of infection.

Standard vaccines train the body to make antibodies against one stable target. With HIV, that target keeps moving. According to the WHO, more than 250 different HIV strains circulate worldwide. A vaccine must protect against many of them at once.

That is why researchers now focus on so-called broadly neutralising antibodies, or bnAbs. These are rare antibodies that can block many HIV variants. About 10 to 25 percent of people living with HIV produce them naturally, but usually too late to help themselves.

What recent trials show

The past two years brought several important results. Some were disappointing. Others opened new doors.

In January 2023, the large Mosaico trial (HVTN 706) was stopped. The vaccine was safe but did not prevent HIV infection in gay and bisexual men and transgender people. This was the last big trial of the older 'mosaic' vaccine approach.

Since then, attention has shifted to mRNA technology. This is the same platform used for the COVID-19 vaccines. In 2022, the IAVI G002 trial showed that an mRNA vaccine could start the immune system on the path to making bnAbs. A follow-up study, IAVI G003, tested the approach in Rwanda and South Africa. Results published in 2024 in Science confirmed the immune response works across populations.

The approach is called germline targeting. It uses a series of vaccines to slowly train rare immune cells to make the right antibodies. The strategy was developed by Scripps Research and IAVI. Experts say it may take three or four shots to get there.

Long-acting prevention is changing the picture

While a vaccine is still years away, prevention has improved fast. Long-acting injectable PrEP is now available in many countries. Cabotegravir, sold as Apretude, is given as an injection every two months. A 2021 study in The Lancet showed it was more effective than daily oral PrEP pills.

Even more striking are the 2024 results for lenacapavir. This drug, given as a shot twice a year, showed 100 percent protection in women in the PURPOSE 1 trial. A second trial in gay and bisexual men, PURPOSE 2, showed 96 percent protection. The journal Science named lenacapavir its Breakthrough of the Year in 2024.

This raises a fair question: if a twice-yearly injection works almost perfectly, do we still need a vaccine? Most experts say yes. Vaccines are usually cheaper to scale, easier to deliver in low-income countries, and do not require ongoing medical contact.

What this means for you

For now, the best HIV prevention tools are the ones already available. The Dutch Aidsfonds and the WHO recommend a layered approach:

• PrEP — daily pills or long-acting injections for people at higher risk of HIV
• Condoms — still effective against HIV and other STIs
• Regular testing — every 3 to 6 months for sexually active gay and bisexual men, according to RIVM guidance
• U=U — people living with HIV on effective treatment cannot pass it on

If you are interested in joining a vaccine trial, organisations like the HIV Vaccine Trials Network (HVTN) regularly recruit volunteers. Trials need participants from many backgrounds to produce useful results.

The global picture

About 39 million people live with HIV worldwide, according to UNAIDS 2024 data. In 2023, around 1.3 million people were newly infected. New infections are falling in most regions, but progress is uneven.

Sub-Saharan Africa still carries the biggest burden. In Eastern Europe and Central Asia, infections are rising. Funding cuts to global HIV programmes — including recent reductions in US foreign aid — worry public health experts. They warn that progress could stall without sustained investment.

This context matters for vaccine research. A vaccine that only reaches wealthy countries would not end the epidemic. Researchers like those at IAVI emphasise that trials in Africa are not just ethical — they are scientifically essential. HIV strains differ by region.

What to expect in the coming years

Scientists are realistic. Dr. Larry Corey of the Fred Hutchinson Cancer Center, a long-time HIV vaccine researcher, has said publicly that a licensed vaccine is probably still 5 to 10 years away. The next big milestone will be phase 2 trials of mRNA-based germline targeting vaccines, expected to start in 2025 and 2026.

In the meantime, the message from HIV Vaccine Awareness Day 2025 is twofold. First: the science is moving, even if slowly. Second: we already have powerful tools to prevent HIV today. Using them well saves lives now.

For more on related health topics, see our coverage of sober sex trends in the gay community and recent research on trans youth and hormone therapy.

Practical tip: If you are sexually active and unsure about your HIV risk, talk to your GP or a sexual health clinic. In the Netherlands, Soa Aids Nederland offers free, anonymous advice online.