News & events


29 August 2014

HIV Prevalence versus Incidence … unpacking the confusion

The Communication Initiative Network

Every few years a national HIV study comes out and people start to speak with great concern about the prevalence and incidence rates increasing. There seems to be a lot of confusion around the difference between the two. The purpose of this article to to unpack the difference between Prevalence and Incidence and explore each one’s relevance.

Prevalence is simple: The total number of people infected with HIV, no matter when they got infected, as a percentage of the total population. For example, in 2012 the HIV prevalence for all people older in South Africa was 12.2% according to the Human Sciences Research Council (HSRC) Report. This works out to be about 6,400,000 people living with HIV out of a total population of about 53 million.

Prevalence rates can be worked out for specific groups, such as babies, youth, and adults of specific ages, and for men versus women. For example, for the population aged 15 to 49 – the more sexually active part of the population – the prevalence rate is 18.8%. The prevalence rate four years ago for this group was 16.9%. So there has been an 11% increase in HIV prevalence in this age group over the last four years. What does this mean? Are things getting much worse? Is treatment and prevention failing? What is going on?

Read the article online

The Communication Initiative Network