Had there been additional efforts to reach and maintain men in treatment services with HIV suppression at levels equal to that of their female counterparts between 2016 and 2018, half of the new infections in adolescent girls and women could have been averted, bringing gender equality in the HIV burden. An international team of researchers recently published these findings as a pre-print, which means they have not yet been reviewed by other scientists.
The investigators found that the contribution of men to transmission is growing, mainly due to low viral load suppression rates. In 2018, although the majority of people with HIV in rural Uganda were women, half of the people with unsuppressed viral load were men and they accounted for 63% of all HIV transmissions.
The study also found that the primary burden of incidence is shifting from adolescents to women aged 25-34 years.
"Age-specific transmission flows shifted; the share of transmission to girls and women aged 15-24 years from older men declined by approximately one third, whereas the contribution of transmission to women aged 25-34 years from men aged 0-6 years older doubled from 2003 to 2018," the authors write.
This study suggests that male-targeted HIV programmes to increase HIV suppression are critical to reducing new cases in women, closing gender gaps in HIV burden and improving men's health in Africa.
Using 15 years of population-based epidemiological and molecular surveillance data from the Rakai Community Cohort Study in Uganda, the investigators measured the changes in HIV transmission by gender and age from 2003 to 2018.
A total of 36,988 participants aged 15 to 49 with an HIV risk profile typical of eastern and southern Africa were enrolled in the study. The majority (61%) were HIV-negative and contributed an estimated 127,217 person-years of follow-up. (Person years take into account how long each participant was followed by the researchers.)
The researchers followed these individuals and documented 1100 new HIV diagnoses. To look at transmission networks they genetically analysed the HIV virus from individuals with sufficient viral loads and identified connections between them.
HIV incidence is declining faster in men than in women
New HIV cases among men fell by 68% from 1.05 to 0.34 per 100 person years (PY) between 2003 and 2018, with no substantial change in their median age. (If incidence was 1.05 per 100 person-years, this means that around 1 in 100 people acquired HIV in one year.)
In young women aged 15 to 24, incidence rates fell similarly by 75% from 1.42 to 0.36 per 100 PY between 2003 and 2018.
However, among women aged 25-34 and 35-49, declines in new HIV diagnoses were substantially slower at 44% and 37%, respectively. This shifted the median age of acquisition in women from 23 years in 2003 to 28 years in 2018.
Transmission from men is increasing and shifting to older ages
In 2003, 58% of HIV transmissions were from men, increasing to 63% in 2018. The median age of transmitting male partners increased from 29 years in 2003 to 33 years in 2018. This increase was largest in transmissions to women aged 20-24.
Over time, fewer women aged 15-24 acquired HIV, but the median age difference between them and their partners increased to nine years. This shows that contact with considerably older men is the main transmission flow into adolescent girls and young women. And while this transmission flow has weakened overall, it remains the predominant route for HIV in adolescent girls and young women.
Among women aged 25-34, transmissions from male partners 0-6 years older increased from 8.5% in 2003 to 13.2% of all HIV transmissions in 2018.
Gender gaps in viral suppression are increasing
By 2018, there was a huge gap in viral suppression rates in men compared to women.
At age 20, 60% of women with HIV had suppressed virus compared to 29% in men with HIV; while at age 30, this was 76% in women versus 55% in men; and at age 40, this was 92% in women versus 76% in men.
In 2018, although the majority of people with HIV were women, half of the people with unsuppressed viral load were men and they accounted for 63% of all HIV transmissions.
This suggests that faster rises in female HIV suppression could partly explain the faster declines in male HIV incidence. Higher rates of ART uptake and virus suppression in women mean that male partners are less likely to acquire HIV.
Closing the suppression gap in men could be the solution
Using simulations, the investigators modelled three scenarios:
- If half the viral suppression gap in men had been closed in 2018, there would have been 25% fewer new HIV cases in women.
- If men had the same viral suppression rates as women in 2018, there would have been 51% fewer new HIV cases in women.
- If the UNAIDS 95-95-95 target of 86% of men with HIV being virally suppressed had been achieved in 2018, there would have been 58% fewer new HIV cases in women.
All three male-targeted intervention scenarios involved reaching viral suppression in no more than 200 additional men, compared to the thousands of women with a higher risk of HIV acquisition in the same study areas.
The researchers predict that closing the suppression gap in men would have changed the female-to-male incidence rate ratio from 1.59 to 0.77 in 2018, entirely closing the growing gender disparity in HIV acquisitions.
These findings reinforce calls for HIV prevention programmes and services centred on reaching and retaining men with HIV in care. This will improve male health, reduce new HIV acquisitions in women by half and close the gender gap in new HIV diagnoses, they conclude.
Monod M et al. Growing gender disparity in HIV infection in Africa: sources and policy implications. medRxiv 2023.03.16.23287351 (preprint, open access)