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-1, the most common type of HIV worldwide, is not a single uniform virus. It is classified into groups and subtypes (also called clades) that evolved separately in different parts of the world. In the UK, most infections are subtype B (historically the dominant strain in Western Europe and North America) or subtype C (common in sub-Saharan Africa and South Asia), but other subtypes and recombinant forms are also seen.
Here’s what subtypes mean and whether they affect your care.
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What Are HIV-1 Subtypes?
HIV-1 is divided into four groups: M (major), N, O and P. Group M accounts for over 90% of global infections and is further split into subtypes:
| Subtype | Main Geographic Distribution |
|---|---|
| A | East Africa, Central Asia |
| B | Western Europe, Americas, Australia |
| C | Southern and East Africa, India |
| D | East and Central Africa |
| CRF01_AE | Southeast Asia |
| CRF02_AG | West Africa |
| Others (F, G, H, J, K) | Various regions |
Circulating recombinant forms (CRFs) are hybrids of two or more subtypes.
Do Subtypes Affect Treatment?
All standard antiretroviral drugs work against all HIV-1 group M subtypes. Your treatment regimen does not change based on which subtype you have. Resistance patterns can differ slightly between subtypes, but this is managed through standard resistance testing before starting treatment.
Do Subtypes Affect Testing?
Modern 4th-generation HIV tests detect all group M subtypes reliably. Some older or cheaper tests may have slightly lower sensitivity for rarer subtypes or group O, but this is uncommon in UK clinical practice. If you are concerned about a specific exposure to an unusual subtype, a 4th-generation lab test is the best option.
Do Subtypes Affect Disease Progression?
Some research suggests modest differences in how quickly untreated HIV progresses between subtypes, but these differences are small compared to the overwhelming benefit of treatment. On effective ART, outcomes are similar regardless of subtype.
Why Subtypes Matter for Vaccine Research
HIV’s diversity is one of the main reasons a universal vaccine has been so difficult to develop. A vaccine that works against subtype B may not protect against subtype C, for example. Researchers are working on broadly neutralising antibodies and mosaic vaccines that target multiple subtypes.
Read more: What is HIV? | HIV vaccine research | HIV and the immune system
Frequently Asked Questions
Does my subtype affect which drugs I take?
No. Standard HIV treatment works against all common subtypes. Your HIV team will run resistance testing to choose the best regimen regardless of subtype.
Can I be infected with two different subtypes?
Yes, though it’s uncommon. This is called superinfection or dual infection and can make treatment slightly more complex.
Will my home test detect all subtypes?
CE-marked tests used in the UK detect all common group M subtypes. Very rare group O or N infections may occasionally be missed by some tests, but this is exceptionally uncommon in the UK.
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.
