References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
HIV comes in two main types: HIV-1 and HIV-2. HIV-1 is responsible for the global pandemic and accounts for the vast majority of infections worldwide. HIV-2 is less common and is mainly found in West Africa. They have different origins, behaviours and treatment considerations, though both ultimately damage the immune system if untreated.
Here’s a clear comparison.
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Key Differences
| Feature | HIV-1 | HIV-2 |
|---|---|---|
| Origin | Chimpanzees (Central Africa) | Sooty mangabey monkeys (West Africa) |
| Global prevalence | Over 95% of cases | Small minority, mainly West Africa |
| Transmissibility | Higher | Lower |
| Progression to AIDS | Typically 8-10 years without treatment | Slower progression |
| Mother-to-child transmission | Higher rates without treatment | Lower rates |
| Viral load levels | Usually higher | Usually lower |
| Response to NNRTIs | Susceptible | Naturally resistant to NNRTIs |
| Test detection | Most tests detect | Some older tests miss it |
HIV-1 Explained
HIV-1 is the main cause of the HIV pandemic. It has multiple groups and subtypes:
- Group M is the most common, responsible for most infections
- Further divided into subtypes (A, B, C, D, etc.)
- Different subtypes dominate in different regions
- All modern treatments work against all group M subtypes
HIV-2 Explained
HIV-2 is primarily found in West Africa but can be found elsewhere in communities with ties to that region:
- Less infectious than HIV-1
- Slower disease progression
- Some people can have very long-term HIV-2 without symptoms or treatment
- Treatment is more complex due to drug resistance patterns
Treatment Differences
HIV-2 has natural resistance to some drug classes, particularly NNRTIs (like efavirenz or rilpivirine) and fusion inhibitors. Treatment regimens for HIV-2 usually use:
- Integrase inhibitors (dolutegravir, bictegravir)
- Protease inhibitors
- NRTIs
These work effectively against HIV-2, though the choice of regimen is more limited.
Testing Considerations
- Modern 4th-generation tests usually detect both HIV-1 and HIV-2
- Confirmatory testing can distinguish between the two
- Some older tests might miss HIV-2
- If you’re from or have travelled to West Africa, mention this to your clinician
Can You Have Both?
Dual infection (having both HIV-1 and HIV-2) is possible in regions where both circulate. Management is more complex and requires specialist input.
Does It Matter Which You Have?
Yes — for treatment choice and prognosis. Your HIV clinic will confirm which type you have and select appropriate medication. The good news is that both can be managed effectively with modern care.
Read more: HIV-1 subtypes | What is HIV? | HIV and the immune system
Frequently Asked Questions
Is HIV-2 less serious than HIV-1?
HIV-2 progresses more slowly and has lower transmissibility, but without treatment it can still cause AIDS. Both need medical management.
Do UK sexual health clinics test for HIV-2?
Standard 4th-generation HIV tests detect both. Confirmatory testing identifies the specific type.
Can HIV-1 treatment be used for HIV-2?
Some drugs work for both; others don’t. NNRTIs are ineffective against HIV-2. Your HIV team will choose the right regimen.
Related reading
- Injectable HIV Treatment: Everything You Need to Know
- Are HIV Tests Accurate If You're on PrEP, PEP or ART?
- CD4/CD8 Ratio: What It Means and Why It Matters
- CD4 Counts Explained: What Your Numbers Mean
- Changing HIV Treatment: When, Why and How
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
