International support for the fight against AIDS that enables the treatment of millions of people in resource-poor countries has led to a 68% reduction in the number of new infections and a 74% reduction in the number of deaths from HIV/AIDS between 2010 and 2023. This has been made possible by antiretroviral treatment: in treating infected people, it not only prevents disease progression and death, but also prevents them from transmitting the virus. Moreover, the use of pre-exposure prophylaxis [PrEP] to protect the uninfected reduces transmission. The impact of treatment and prevention measures on transmission and disease progression is therefore known in a precise and quantifiable way.

The authors apply an epidemiological model that reflects recent evidence on HIV transmission, disease progression and the impact of interventions - treatment, PrEP, etc. - on transmission and progression. The model stratifies populations according to their demographic and risk group, the degree of progression based on CD4 [cell] count and whether they are on treatment or not. It considers three types of transmission: sexual, needle exchange and vertical mother-to-daughter transmission. It estimates the impact of treatment on both transmission of infection in the different models and progression to death according to the degree of disease progression. It applies the model to 26 countries that collect these data systematically and extrapolates to all other resource-limited countries.

Given the announcement of the restriction of aid funding for HIV treatment announced by various countries, the authors do not analyse the impact of treatment on the improvement of the situation, but rather the impact of NO treatment on the worsening of the epidemiological scenario in the countries that depend on this aid. In particular, they analyse the impact of the temporary suspension of the PEPFAR programme, which provides 72% of total funding, by the current US administration. The article considers five scenarios, ranging from business as usual (statu quo) to the worst case scenario, which would entail the disappearance of the PEPFAR programme without any impact mitigation measures. This comparison is particularly useful for assessing the different situations that affected countries face depending on the mitigation measures put in place. The article makes for complex reading but the data is shocking, especially in scenarios 4 and 5. Scenario 4 envisages that 75% of funding can be recovered from other sources from January 2027. Scenario 5 analyses what would happen in countries that are more than 40% dependent on PEPFAR - Mozambique is 98% dependent - and that have to take on this loss with their own resources progressively between 2025 and 2030 (no mitigation measures).

The model projections predict in scenario 5 that, in the 26 countries analysed, between 2025 and 2030, there would be an excess of 5.13 million transmissions and 1.38 million deaths over what would occur if the statu quo were maintained. A situation that, extrapolated to all resource-poor countries, would increase to 10.75 million and 2.93 million transmissions and deaths respectively. The 90-day interruption of the PEPFAR programme announced by the US Administration alone will result in between 40,000 and 100,000 excess deaths. The damage is already done and in the worst-case scenarios we would be back to the 2004 situation, losing two decades of improvement in controlling the HIV/AIDS epidemic.

The model, like all models, has uncertainties and criticisms, but it is based on real data because we know from many studies the impressive impact of treatment on HIV transmission and progression to AIDS and the death of those infected. We have experienced this and unfortunately the degree of uncertainty of running the inverse model (from treatment to non-treatment) is low.

Beyond the assessment of the article, two comments. What has been achieved so far has been very important but still insufficient. In 2023, 630,000 people died of AIDS and 120,000 children became infected with HIV worldwide due to lack of treatment. But as our colleagues in those countries tell us, the discontinuation of PEPFAR has sown chaos as millions of people have been left without treatment overnight. The scenario of slow progress towards 90% control of transmission and deaths by 2030 may turn into a nightmare scenario in many countries where women, adolescents and newborns will be the most affected.

At the recent Retrovirus Conference in San Francisco, we were told these facts but also reminded that PEPFAR ( US President's Emergency Plan for AIDS Relief), the largest AIDS programme ever undertaken in resource-poor countries, was introduced by President Bush in 2008, who justified it with a quote from the book of Deuteronomy (30:19): ‘Today I make heaven and earth a witness against you, that I have given you a choice between life and death, between a blessing and a curse. So choose life, that you and your descendants may live’.

The study, published in The Lancet HIV by Debra ten Brink et al on 26 March 2025, applies mathematical modelling (‘Optima HIV’) to 26 low- and middle-income countries to estimate how cuts in international funding (mainly PEPFAR and other donors) could impact on new HIV infections and deaths between 2025 and 2030.

The cuts in international funding described in the study directly threaten UNAIDS' 2030 targets, which aim for a 90% reduction in new HIV infections and deaths compared to 2010, and the achievement of 95-95-95 in diagnosis, treatment and viral suppression. Some of the key findings of this study include:

• Reversal in the sustained decline in new infections. Projections indicate a marked increase in cases if aid reductions - especially the cessation of PEPFAR - are not mitigated. This makes it more difficult to achieve the 90% reduction in infections, as much of the progress in prevention depends on donor funding, especially in key populations such as migrants, sex workers, men who have sex with men, people who inject drugs or transgender people.
• Increase in the number of new HIV infections and mortality. If the cuts are not offset, there would be an excess of between 4.43 million and 10.75 million new HIV infections and between 0.77 million and 2.93 million HIV-related deaths between 2025 and 2030. Treatment interruption and declines in community-based programmes would hinder retention in care and maintenance of viral suppression.
• Disproportionate impact. Withdrawal of aid impacts more on sub-Saharan Africa (especially children) and key populations in other regions. This uneven effect clashes with the UNAIDS approach of ‘leaving no one behind’ and delays the achievement of the 95-95-95 targets among the most vulnerable groups.
• Need for sustainable mechanisms. The study reinforces the urgency of mobilising domestic resources, optimising programmes and finding other sources to sustain universal coverage of prevention, diagnosis and antiretroviral therapy. Without this step, the UNAIDS global targets to eradicate HIV as a public health threat are unlikely to be met by 2030.