Estimating how many people living with HIV are on treatment is vital to keeping track of the success or otherwise of the global AIDS response. HIV treatment not only keeps people alive, but, through reducing the viral load of a person, greatly reduces the chance that a person living with HIV will transmit the virus to someone else.

UNAIDS published its latest estimates of the number of people living with HIV accessing antiretroviral therapy in its new report, Miles to go. An estimated 21.7 million [19.1–22.6 million] people of the 36.9 million [31.1–43.9 million] people living with HIV at the end of 2017 were on HIV treatment.

A total of 143 countries submitted the data that UNAIDS used to compile the estimate, representing 91% of all people estimated to be on treatment worldwide. Those 143 countries supply actual counts of people on treatment, not estimates, although estimates are used for those few countries that do not supply counts. Countries report their numbers of people on treatment—both adults and children, disaggregated by sex—through the Global AIDS Monitoring tool every six months. Similar data are included in the Spectrum epidemiological estimation software.

UNAIDS provides technical assistance and training to public health officials and clinical officers—the people who compile the numbers in the countries—to ensure that their reports on treatment coverage are accurate. In addition, every year, in partnership with the United Nations Children’s Fund, the World Health Organization and other partners that support the delivery of HIV treatment services, UNAIDS reviews and validates the treatment numbers reported through both the Global AIDS Monitoring tool and Spectrum. Read more via UNAIDS