While HIV-1 and HIV-2 closely relate and can cause similar health concerns, there are some important differences to know — especially when it comes to transmission, testing, and treatment.
HIV-1 and HIV-2 are two different types of HIV. Without treatment, both
However, HIV-1 is much more common worldwide, accounting for about 95% of all HIV cases. HIV-2 is less common and mostly present in West Africa, although people have reported cases elsewhere, including in the United States and Europe.
HIV-2 generally transmits less efficiently, tends to have a longer symptomless period, and may be less likely to progress to stage 3 HIV than HIV-1. People with HIV-2 typically have a
HIV-1 and HIV-2 are transmissible in the same ways, including through:
- sexual contact
- sharing needles or syringes
- pregnancy, childbirth, or breast milk
- transfusions of blood or blood products (rare in countries with routine blood screening)
HIV-2 is less likely than HIV-1 to be transmissible perinatally or through sexual contact.
Still, it’s important to remember that both types can be transmissible and can lead to serious health complications without treatment.
Standard HIV testing can help doctors detect HIV infections, but not all tests differentiate between HIV-1 and HIV-2.
Here are how standard HIV tests may help doctors detect HIV-1 or HIV-2:
- Antibody tests may help doctors detect both types but don’t always distinguish between them.
- Combination (antigen/antibody) tests can help doctors detect HIV-1 earlier than HIV-2 because it’s easier for the test to pick up on HIV-1’s p24 antigen.
- Doctors often use differentiation assays after an initial positive test to determine which type of HIV is present.
- Doctors use nucleic acid tests less often, but they can help doctors detect HIV-1 and HIV-2 at the genetic level if necessary.
HIV-2 infections can sometimes take longer to detect because they often produce lower levels of virus in the blood early on.
It’s also possible, though uncommon, to contract HIV-1 and HIV-2 at the same time.
Antiretroviral therapy (ART) can treat HIV-1 and HIV-2. However, not all medications work equally well for both types.
HIV-1 is typically treatable with a standard ART regimen that includes two nucleoside reverse transcriptase inhibitors plus a third drug, often an integrase inhibitor, protease inhibitor, or non-nucleoside reverse transcriptase inhibitor (NNRTI).
HIV-2 is naturally resistant to some common HIV-1 treatments, especially NNRTIs. Protease inhibitors and integrase inhibitors are usually more effective options for treating HIV-2.
Because of these differences, anyone with HIV needs to know whether they have HIV-1, HIV-2, or both. Treatment plans can be adjustable to match the specific type.
Without treatment, HIV-1 and HIV-2 can lead to stage 3 HIV. However, HIV-2 tends to progress more slowly. People with HIV-2 may live for many years without significant symptoms or negative health effects on the immune system.
Some research suggests that people with HIV-2 may be more likely to reach and maintain an undetectable viral load than those with HIV-1, especially early in the infection.
That said, complications can still happen with either type, including an increased risk of opportunistic infections if people don’t manage the virus with medications.
With early diagnosis, proper treatment, and regular medical care, people with HIV-1 or HIV-2 can live full lives.
HIV-1 and HIV-2 closely relate but have important differences in their transmission routes, how fast they progress, and how doctors treat them.
While HIV-1 is more common worldwide, HIV-2 tends to transmit less efficiently and may have a better overall outlook. Still, both require appropriate treatment and regular healthcare follow-up.
If you have HIV — or think you might have experienced exposure — getting tested and connecting with a healthcare team can help you find the right treatment plan and support you need.