Q&A: Sub-Saharan Africa has achieved great declines in HIV

This transcript has been lightly edited for clarity

What was the scope and purpose of your study?

We tried to bring together all available data and integrate it into modeled estimates of the burden of HIV. So new infections, incidence, number of people living with HIV, prevalence, and HIV-related deaths, mortality.

And we do that for 204 countries and territories for the past, and then we assessed past trends and relationships and used those to forecast them out to 2050. And the results of these analyses allow us to make comparisons between countries, how are they doing, and then also within a given location, assess progress made over time. And the idea is that that work will contribute to policymaking at the local level or at the more global level.

What are the key findings from your study?

Globally, we’re seeing substantial declines in new infections and deaths between 2010 and 2021.

Global new infections in our estimates decreased from over 2 million in 2010 to 1.65 million in 2021. This is an over 20% decrease. And new infections are one of the main indicators we’re interested in.

We want to see declines in this. The achievements here are largely due to increased ART coverage, the abbreviation for antiretroviral therapy, and a reduction in the number of people who are able to transmit HIV due to protection from treatment.

Our study also estimated declines in HIV-related deaths from 1.2 million in 2010 to over 700,000 in 2021, and this is almost a 40% decrease. This much larger reduction in deaths indicates the fast action in the life-saving treatment that’s being delivered. So the reductions in infections can take place over a longer time period, but reduction in mortality actually can take place quite quickly. If people who are sick get put on treatment, their life expectancy improves dramatically.

What changes are you seeing in HIV statistics in sub-Saharan Africa?

Sub-Saharan Africa has achieved great declines in both new infections and the number of deaths. We introduced two new metrics in this paper to seek to really characterize how well sub-Saharan Africa is doing.

In sub-Saharan Africa, we estimated PUV, which is the prevalence of unsuppressed viremia, of 1,000 people per 100,000 in 2021. And this is a 65% decrease from what we observed in 2003. This metric, PUV, measures the proportion of the population that has an unsuppressed viral load and, therefore, is at risk of transmission. So rather than focusing on the total population living with HIV, we narrow our focus to just the individuals who are at risk of transmission.

The second metric, which is the probability of lifetime acquisition of HIV, this characterizes current incidence rates, and if they were to occur, how likely someone born in the current period would be to acquire HIV over their lifetime. In both these metrics, sub-Saharan Africa is outperforming all other regions in the world, and they’re achieving great declines in the number of people who are at risk of transmitting or who are at risk of acquiring the virus.

What we’re looking at is improvement, relative to peak, and seeing that the high burden present in sub-Saharan Africa created an environment where a lot of action was needed.

And so funding has come in and governments have put great focus into getting people tested, getting them onto treatment. And this reduces the actual risk of transmission. So, treatment prevents death, but it also can prevent new infections. And that phenomenon in sub-Saharan Africa is resulting in great improvements.

Where is the news less positive?

In Central Europe, Eastern Europe, and Central Asia, an area of concern is fairly dramatic increases in the period lifetime probability of HIV acquisition. This metric characterizes if age-specific incidence rates were to hold constant for an individual born in this year, what would be their lifetime probability of acquiring HIV? So, the change that occurred was an increase to 2.8%. And this is almost a six-times increase from what was observed in 1995.

What are the forecasts for people living with HIV through to 2050?

People living with HIV is a complicated metric to view in isolation because it reflects increases in the number of people who are getting infections. But it also can reflect extended life expectancies for people who get put on treatment. So, what we’re seeing here is, over time, in 2021, we have 40 million people living with HIV; this increases to 43.7 and peaks at 44.4 in 2039, and then declines to 43.4 in 2050. And this delayed decline reflects that a large cohort of people who were put on treatment in an era where HIV burden was much higher live out their lives and new infections go down. And we reach a tipping point in 2039 where people living with HIV reaches its peak.