HIV

1. Key messages

2. New diagnoses of HIV infections in 2021

In 2021, 781 new diagnoses of HIV infections were made in Belgium (6.7 new diagnoses per 100.000 inhabitants, or on average 2.1 cases a day). Among those, 74% were men. 76% of the HIV cases were diagnosed in people aged 20-49.

New HIV diagnoses have increased in 2021 - but are still lower compared to previous years

The number of new HIV diagnoses has increased by 4.3% in 2021 compared to the previous year. But in comparison to previous years, the total number of new HIV diagnoses is still substantially lower (-17% compared to 2019).

Between the start of the epidemic in the early 80s and the end of 2021, a total of 34.010 persons were diagnosed with HIV, and a total of 5,296 cases of AIDS were reported.

Brussels has a higher diagnosis rate compared to the rest of Belgium

In 2021, of the 781 new diagnoses, 251 cases were reported in the Brussels Capital Region, 354 in the Flemish Region, 161 in the Walloon region, and 14 cases were residing abroad.

When accounting for the number of inhabitants, the incidence rates in the Flemish Region and in the Walloon Region are comparable, while the rate in the Brussels Capital Region is much higher. This difference is not surprising since a higher HIV prevalence is a common phenomenon in a big city. The Brussels Capital Region can indeed be considered a big city - with the socio-cultural characteristics of an urban context – while the two other regions mix rural, semi-urban, and urban contexts.

A decrease in new diagnoses has been observed in Brussels, while for Flanders and Wallonia, the number of diagnoses increased

In 2021, the slight decrease in the number of new HIV diagnoses in the Brussels Capital Region that has been observed in the previous years has continued. There was a large decrease in the number of diagnoses in the Flemish Region and the Walloon Region in 2020, this was followed by a slight increase in 2021.

Diversification in the 2-key populations in Belgium

Since the start of the HIV epidemic in Belgium, two key populations have been particularly affected: men who have sex with men (MSM), of Belgian nationality, and heterosexual men and women from sub-Saharan Africa.

However, among both MSM and heterosexuals, the distribution of nationalities is changing significantly over time. Among people infected by heterosexual contact, the share of people of sub-Saharan nationality is decreasing (64% in 2012 to 45% in 2021). Among MSM, a decreasing share of new diagnoses in Belgian was observed since 2013. However, HIV transmission appears to have increased among Belgian MSM in 2021, as suggested by the increase in the number of acute infections among this group in 2021, reaching approximately the same number as in 2019.

More than a thousand people in Belgium live with an undiagnosed HIV infection

In 2021, Sciensano has estimated the number of people living with undiagnosed HIV [1] based on a tool developed by ECDC [2]. 1,155 people living with HIV in Belgium were not aware of their seropositivity. Based on the ECDC tool the number of people living with undiagnosed HIV in Belgium seems to decrease. In 2020, 1585 people in Belgium were unaware of their HIV infection.

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Background

Transmission of HIV

Sexually transmitted infections (STIs) such as human immunodeficiency virus (HIV) are spread primarily through person-to-person sexual contact. Additionally, HIV can be transmitted through blood products and tissue transfer, and from mother to child during pregnancy or breastfeeding.

HIV can be present without symptoms, which can facilitate transmission. It is one of the most serious communicable diseases in Europe. Infection with the virus can, if antiretroviral treatment (ART) is not initiated, lead to serious morbidity (Acquired Immunodeficiency Syndrome (AIDS)) and requires life-long treatment.

HIV is an avoidable infection since the transmission is largely preventable by behavioural measures (safe sex, safe injection). Therefore HIV incidence in a defined population is an indicator of the success/failure of control strategies. Since 2017, the use of pre-exposure prophylaxis to HIV (PrEP) is reimbursed in Belgium.

Surveillance of HIV in Belgium

The epidemiological surveillance of HIV in Belgium dates from 1985 and is carried out by Sciensano on the basis of the registration of new HIV diagnoses. These data are reported by the seven AIDS reference laboratories that perform all confirmations of positive HIV screening tests. In addition to recording the number of newly diagnosed HIV positive, the laboratories also collect basic epidemiological data on gender, age, nationality, probable route of infection, and clinical stage at the time of diagnosis. Sciensano also collects data on the people living with HIV (PLWH) in Belgium (HIV cohort data) from the AIDS reference laboratories and the HIV reference centres.

Besides the newly diagnosed cases, Sciensano also estimates the number of people living with HIV: those who have not yet been diagnosed [1] and those living with a diagnosed infection. To estimate the undiagnosed population an instrument developed by the European Center for Disease Prevention and Control (ECDC), called the ECDC HIV Modeling Tool [2] is used. And HIV cohort data are used to estimate the number of people living with a diagnosed infection.

ECDC and the WHO Regional Office for Europe jointly coordinate HIV/AIDS surveillance in Europe [3]. The international comparability has some limitations since the national surveillance systems differ in levels of underreporting and reporting delay.

Definitions

HIV/AIDS

HIV infection and AIDS are the acronyms of "Human Immunodeficiency Virus" (HIV) infection and "Acquired Immune Deficiency Syndrome" (AIDS). Initial HIV infection is most often asymptomatic, while people may experience influenza-like symptoms. This is followed by a prolonged period with no symptoms. If the infection progresses, it interferes more with the immune system, increasing the risk of developing infections such as tuberculosis, as well as other opportunistic infections, and tumours which are rare in people who have a normal immune function. These late symptoms of infection are referred to as AIDS. Since the late 1990s, efficient antiretroviral treatment exists that can slow down the progression of the disease.

References

[1] Epidémiologie du SIDA et de l'infection à VIH en Belgique. Situation au 31 décembre 2021. Brussels: Sciensano; 2022. https://www.sciensano.be/sites/default/files/rapport_vih_2022_fr.pdf

[2] European Centre for Disease Prevention and Control. HIV Modelling Tool. 2015. https://www.ecdc.europa.eu/en/publications-data/hiv-modelling-tool

[3] European Centre for Disease Prevention and Control/WHO Regional Office for Europe. HIV/AIDS surveillance in Europe 2022 – 2021 data. Stockholm: ECDC; 2022. https://www.ecdc.europa.eu/sites/default/files/documents/2022-Annual_HIV_Report_final.pdf

Please cite this page as: Sciensano. Communicable Diseases: HIV, Health Status Report, 12 Jan 2023, Brussels, Belgium, https://www.healthybelgium.be/en/health-status/communicable-diseases/hiv-and-other-sexually-transmitted-infections