Subtype C is half of global HIV, and the map has not moved much

Design

systematic review with global collaborative survey of unpublished data, aggregated by country across six time periods and weighted by UNAIDS prevalence estimates

Population

1,395,222 HIV-1 samples from 154 countries, 1990-2024

Primary outcome

proportion of HIV-1 subtypes, circulating recombinant forms and unique recombinant forms, globally and by region

Effect

in 2020-24, subtype C 48.7% (95% CI 48.3-49.1), A 11.5%, B 10.3%, unique recombinants 5.3%, CRF02_AG and CRF01_AE 5.1% each

HIV-1 genetic diversity affects diagnostic assays, viral load quantification, resistance pathways and vaccine design, and the last comprehensive picture is now old. This systematic review combined published subtyping data with a global survey of unpublished data, covering 1,395,222 samples from 154 countries between 1990 and 2024, weighted by UNAIDS estimates of people living with HIV.

In 2020-24, subtype C accounted for 48.7% of global infections (95% CI 48.3-49.1), followed by subtype A at 11.5%, subtype B at 10.3%, unique recombinant forms at 5.3%, CRF02_AG and CRF01_AE at 5.1% each, subtype G at 3.1% and subtype D at 3.0%. The geography is distinct: subtype C dominates southern Africa, the Horn of Africa and south Asia; subtype A east Africa, eastern Europe and central Asia; subtype B North America, Latin America and western Europe; CRF01_AE southeast Asia; CRF07_BC east Asia. Central Africa is the most diverse. Distributions were broadly stable from 2000, with recombinants rising in western Europe and CRF07_BC in east Asia.

For a clinician in India this is confirmation rather than news — subtype C is what circulates here — but the practical implications are worth restating. Assay performance, including viral load quantification and some rapid tests, was developed largely against subtype B, and diversity is the reason discordant or unexpectedly low viral loads deserve a second thought rather than a reassuring interpretation.

• Subtype C predominates in India; assays validated mainly on subtype B may perform differently
• Treat an unexpectedly low or discordant viral load as a possible assay issue, not only as adherence
• Recombinant forms are rising in some regions, which complicates resistance interpretation
• Geographic history matters when interpreting resistance testing in a migrant or travelling patient
• Global distribution has been broadly stable since 2000 — this updates the map rather than redrawing it

The statistics, in plain English

The confidence interval on 48.7% (48.3-49.1) is extremely narrow because it reflects sampling within an enormous dataset, not the real uncertainty — subtyping data are not collected evenly across countries, and weighting by UNAIDS prevalence estimates imports whatever error those carry. Countries with little sequencing contribute little data and are represented by their region, so the global figure is more solid than any single country estimate. Data span 1990-2024 aggregated into six periods, so within-period change is invisible.

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