Key Distinctions Between HIV Infection and AIDS: What You Need to Know

HIV is the virus. AIDS is the most advanced stage of HIV infection, when the immune system is badly damaged.

Difference

HIV (human immunodeficiency virus) is the virus that attacks CD4 immune cells. AIDS (acquired immunodeficiency syndrome) is the most advanced stage of HIV, defined by a CD4 count below 200 or by opportunistic infections.

Not everyone with HIV gets AIDS

With antiretroviral therapy (ART), most people with HIV never develop AIDS and live a near-normal lifespan.

Time

Without treatment, HIV takes about 10 years on average to progress to AIDS.

Transmission

HIV spreads through blood, sexual fluids and breast milk. AIDS itself isn’t transmitted.

Testing

Tests detect HIV in blood or saliva. The CDC recommends everyone aged 13 to 64 be tested at least once.

Prevention

Condoms, PrEP and treatment as prevention (U=U).

The difference

HIV (human immunodeficiency virus) is the virus that infects and destroys CD4 T cells of the immune system. AIDS (acquired immunodeficiency syndrome) is the most advanced stage of HIV infection. A person is diagnosed with AIDS when the CD4 count falls below 200 cells per cubic millimeter of blood (normal is 500 to 1,600), or when they develop an AIDS-defining illness such as Pneumocystis pneumonia, Kaposi sarcoma, tuberculosis or certain lymphomas.

Not everyone with HIV gets AIDS

With modern treatment, most people with HIV do not progress to AIDS. Antiretroviral therapy (ART) keeps the virus under control and lets the immune system recover. Without treatment, HIV usually leads to AIDS in about 8 to 10 years, though this varies.

Time

The stages of HIV infection are:

• Acute HIV infection, 2 to 4 weeks after exposure, often with flu-like symptoms and very high viral load.
• Chronic HIV infection (clinical latency), which can last a decade or more without treatment, with few or no symptoms.
• AIDS, when the immune system is severely damaged.

Treated people with HIV can live a near-normal lifespan. A person starting ART at 20 can expect to live into their 70s.

Transmission

HIV is spread through blood, semen, pre-seminal fluid, rectal and vaginal fluids, and breast milk. AIDS itself is not transmitted. You can only get HIV. It spreads through condomless sex, sharing needles, and from mother to child. It does not spread through casual contact, kissing, sharing food or toilets, or mosquitoes.

Testing

HIV tests include antigen/antibody lab tests (detect infection 18 to 45 days after exposure), nucleic acid tests (10 to 33 days) and rapid and self-tests (23 to 90 days). A diagnosis of AIDS is based on CD4 count and symptoms. The CDC recommends that everyone aged 13 to 64 be tested at least once.

Prevention

• Condoms.
• PrEP (pre-exposure prophylaxis), a daily pill or injections every 2 months (cabotegravir) or, from 2025, twice-yearly lenacapavir, which reduce risk by about 99% when used as directed.
• PEP within 72 hours of exposure.
• Treatment as prevention: an undetectable viral load means HIV cannot be sexually transmitted (“U=U”).
• Syringe services and not sharing needles.

About 1.2 million people in the US live with HIV, and around 38,000 new infections occurred in 2022.

Stages and treatment

HIV, the human immunodeficiency virus, attacks CD4 T cells of the immune system. Without treatment, it can progress to AIDS (acquired immunodeficiency syndrome), defined by a CD4 count below 200 cells per cubic millimeter or by opportunistic infections. Today, antiretroviral therapy (ART) lets most people with HIV live a near normal lifespan, and when the viral load is undetectable for 6 months, the virus cannot be passed on sexually, known as U=U. About 1.2 million people in the US have HIV, and about 13 percent do not know it. Globally around 39 million people live with HIV, and 77 percent receive treatment. Without treatment, progression to AIDS takes an average of about 10 years. The CDC recommends everyone aged 13 to 64 be tested at least once, and PrEP medicines reduce the risk of getting HIV from sex by about 99 percent when taken as prescribed.

Based on data from the CDC and the World Health Organization