New research casts doubt on age gap theory of HIV transmission

Hester Philips Avert, 2017; View full article online

An article published by Avert summarises research from South Africa suggesting that a women’s HIV risk may be driven more by their male partner’s age than by the age gap between them. The study led by the US-based Institute for Disease Modeling, took data from around 10,260 women and 7,840 men in KwaZulu-Natal, South Africa and analysed it from 2004 and 2015. New HIV infections were documented in 1,788 women and 579 men.

New HIV infections among women were highest when they were in sexual relationships with men aged 25 to 34, as opposed to the commonly held theory that older men aged 35 and over presented the biggest HIV risk to women. For men, it was women in the age group 25 to 34 that resulted in the highest HIV incidence rates.

The findings reflect a number of factors associated with younger men in this setting:

  • they are likely to engage in risky sexual behaviour, including multiple sexual partnerships
  • they are less likely to be aware of their HIV status and be on antiretroviral treatment than women who acquire HIV
  • they are at heightened risk of having a high viral load associated with acute HIV infection, meaning they are more likely to transmit HIV to others

These results shed new light on the potentially limited role large age gaps have in driving HIV incidence in young women, suggesting that prevention efforts should focus not only on age groups at high risk of HIV acquisition, but also on age groups with high potential for onward transmission.

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