What Is the HIV-2 Strain?

Health experts think around 1 to 2 million people worldwide have HIV-2. But the numbers are likely higher. Doctors and scientists group HIV into 2 subtypes: HIV-1 and HIV-2.¹

The viruses are the same in how you develop and transmit them. But there are some key differences in how HIV-2:¹

• Progresses
• Is treated
• Is managed

What are the similarities and differences between HIV-1 and HIV-2?

Compared to HIV-1, HIV-2 makes up a smaller number of global HIV transmissions, between 3 and 5 percent. In the United States, 1 to 2 percent of people with HIV have the HIV-2 subtype.¹

HIV-2 is most common in Western Africa. But our increasingly connected world has led to the transmission of the disease around the globe. It is now found in other regions of Africa, Europe, India, and the United States. Doctors have diagnosed people with both subtypes in areas where HIV-1 and HIV-2 are present.¹

Differences between HIV-1 and HIV-2

There are a few main differences between HIV-1 and HIV-2. Researchers have found people with the HIV-2 subtype tend to have:¹

• A longer period without developing symptoms
• A slower drop-off in CD4 counts
• Lower plasma viral loads
• A lower rate of death

Similarities between HIV-1 and HIV-2

Despite these differences, if HIV-2 is not treated, it leads to illness and death. People with HIV-2 are still vulnerable to illnesses resulting from weakened immune systems (opportunistic infections). These include:¹

• Candidiasis
• Pneumonia
• Tuberculosis

Research also shows that when CD4 counts fall below 200, the rates of death in untreated HIV-2 and HIV-1 are similar. And both subtypes are transmitted the same way:¹

• Through sexual contact
• Through exposure to blood containing HIV
• To a child during pregnancy, birth, or breastfeeding

Diagnosing and treating HIV-2

As we become more globally connected, doctors must be vigilant in spotting and treating HIV-2. But because there are fewer cases of HIV-2 than HIV-1, there is a lack of research and drug trials for HIV-2. This means less:¹

• Knowledge about how many people have this subtype
• Treatment
• Tracking of the disease

Diagnosing HIV-2

HIV testing has advanced over the years. Now doctors can distinguish HIV-1 from HIV-2. In 2014, the Centers for Disease Control and Prevention (CDC) updated its HIV testing algorithm for better diagnosis of HIV-2. Still, only 2 labs in the United States regularly perform HIV-2 viral load testing.^1,2

Treatment of HIV-2

Antiretroviral therapy (ART) helps prevent the transmission of HIV, boosts your immune system, and lowers your chances of illness and death. People with HIV-2 benefit from this therapy. But it is unclear which ART drugs are most effective and when to start taking them.¹

Researchers have not carried out many studies on ART specifically for the treatment of HIV-2. Instead, most treatment plans for this subtype rely on data about HIV-1. Doctors do know that non-nucleoside reverse transcriptase inhibitors and most protease inhibitors do not work in treating HIV-2. Right now, experts suggest starting ART promptly after diagnosis.^1,3