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                                  Human immunodeficiency virus (HIV) is an infection that attacks the body’s immune system, specifically the white blood cells called CD4 cells. HIV destroys these CD4 cells, weakening a person’s immunity against opportunistic infections, such as tuberculosis and fungal infections, severe bacterial infections and some cancers.

                                  WHO recommends that every person who may be at risk of HIV should access testing. HIV infection can be diagnosed using simple and affordable rapid diagnostic tests, as well as self-tests. It is important that HIV testing services follow the 5Cs: consent, confidentiality, counselling, correct results and connection with treatment and other services. 

                                  People diagnosed with HIV should be offered and linked to antiretroviral treatment (ART) as soon as possible following diagnosis and periodically monitored using clinical and laboratory parameters, including the test to measure virus in the blood (viral load). If ART is taken consistently, this treatment also prevents HIV transmission to others.

                                  At diagnosis or soon after starting ART, a CD4 cell count should be checked to assess a person’s immune status. The CD4 cell count is a blood test used to assess progression of HIV disease, including risk for developing opportunistic infections and guides the use of preventive treatment. The normal range of CD4 count is from 500 to 1500 cells/mm3 of blood, and it progressively decreases over time in persons who are not receiving or not responding well to ART. If the person’s CD4 cell count falls below 200, their immunity is severely compromised, leaving them susceptible to infections and death. Someone with a CD4 count below 200 is described as having an advanced HIV disease (AHD).

                                  HIV viral load measures the amount of virus in the blood. This test is used to monitor the level of viral replication and effectiveness of ART. The treatment goal is to reduce the viral load in the blood to undetectable levels (less than 50 copies/ml), and the persistent presence of detectable viral load (greater than 1000 copies/ml) in people living with HIV on ART is an indicator of inadequate treatment response and the need to change or adjust the treatment regimen. 


                                  Many people do not feel symptoms of HIV in the first few months after infection and may not know that they are infected. Others may experience influenza-like symptoms, including fever, headache, rash and sore throat. However, these first few months are when the virus is most infectious.

                                  As the disease progresses, symptoms will be expanded and more pronounced. These can include swollen lymph nodes, weight loss, fever, diarrhoea and cough. HIV weakens the body’s ability to fight other infections, and without treatment people will become more susceptible to other severe illnesses such as tuberculosis, cryptococcal meningitis, bacterial infections and some cancers including lymphomas and Kaposi’s sarcoma.

                                  Diagnosis of HIV uses rapid tests that provide same-day results and can be done at home, although a laboratory test is required to confirm the infection. This early identification greatly improves treatment options and reduces the risk of transmission to other people including sexual or drug-sharing partners.


                                  HIV is fully preventable. Effective antiretroviral treatment (ART) prevents HIV transmission from mother to child during pregnancy, delivery and breastfeeding. Someone who is on antiretroviral therapy and virally suppressed will not pass HIV to their sexual partners.

                                  Condoms prevent HIV and other sexually transmitted infections, and prophylaxis use antiretroviral medicines to prevent HIV. Male circumcision is recommended in high-burden countries in eastern and southern Africa. Harm reduction (needle syringe programmes and opioid substitution therapy) prevents HIV and other blood-borne infections for people who inject drugs.

                                  HIV is treated with antiretroviral therapy consisting of one or more medicines. ART does not cure HIV but reduces its replication in the blood, thereby reducing the viral load to an undetectable level.

                                  ART enables people living with HIV to lead healthy, productive lives. It also works as an effective prevention, reducing the risk of onward transmission by 96%.

                                  ART should be taken every day throughout the person’s life. People can continue with safe and effective ART if they adhere to their treatment. In cases when ART becomes ineffective due to reasons such as lost contact with health care providers and drug stockouts, people will need to switch to other medicines to protect their health.

                                  37.7 million

                                  people in the world

                                  were living with HIV in 2020.


                                  of all people

                                  living with HIV had access to antiretroviral therapy in 2020.


                                  of all people

                                  living with HIV did not know that they have HIV in 2020.

                                  World AIDS Day 2021

                                  World AIDS Day 2021

                                  End inequalities. End AIDS


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                                  WHO's current HIV testing services guidelines and information

                                  HTS Info app

                                  WHO's consolidated guidelines for HIV treatment and care app.

                                  HIV Tx app

                                  The WHO PrEP Implementation Tool app for health workers

                                  Oral PrEP Tool app