Model shows sharp decrease in HIV incidence in England

To manage the HIV epidemic among MSM in England, enhanced testing and earlier treatment strategies were scaled-up between 2011 and 2015 and supplemented from 2015 by pre-exposure prophylaxis (PrEP). The researchers examined the effect of these interventions on the number of new infections and investigated whether the United Nations (UN) targets for HIV control and elimination of HIV transmission by 2030 might be within reach among MSM in England.

A complexity in this assessment is that HIV infections are not observed. Routine surveillance collects data on new HIV diagnoses, but trends in new diagnoses alone can be misleading as they can represent infections that occurred many years previously and depend on the testing behaviour of infected individuals.

To estimate new HIV infections among adult MSM (age 15 years and above) over a 10-year period between 2009 and 2018, the researchers used a novel statistical model that used data on HIV and AIDS diagnoses routinely collected via the national HIV and AIDS Reporting System in England, and knowledge on the progression of HIV. Estimated trends in new infections were then extrapolated to understand the likelihood of achieving the UN elimination target defined as less than one newly acquired infection per 10,000 MSM per year, by 2030.

The peak in the number of new HIV infections in MSM in England is estimated to have occurred between 2012 and 2013, followed by a steep decrease from 2,770 new infections in 2013 to 1,740 in 2015, and a further steadier decrease from 2016, down to 854. The decline was consistent across all age groups but was particularly marked in MSM aged 25-34 years, and slowest in those aged 45 years or older. Importantly, this decrease began before the widespread roll-out of PrEP in 2016, indicating the success of testing and treatment as infection prevention measures among MSM in England.

Through extrapolation, the researchers calculated a 40% likelihood of England reaching the UN elimination target by 2030 and identified relevant age-specific targeting of further prevention efforts (i.e., to MSM aged ≥45 years) to increase this likelihood.

Senior author, Professor Daniela De Angelis, Deputy Director of the MRC Biostatistics Unit, University of Cambridge, said:

"This is very good news and suggests that prevention measures adopted in England from 2011 have been effective. With the rollout of PrEP, England looks on course to meet the goal of zero transmissions by 2030. Our study also shows the value of regular estimation of HIV incidence to recognise and respond appropriately to changes in the current downward trend. The challenge now is to achieve these reductions in all groups at risk for HIV acquisition."

Valerie Delpech, Head of National HIV Surveillance at Public Health England, said:

"We have made good progress towards ending HIV transmission by 2030 in England. Frequent HIV testing and the use of PrEP amongst people most at risk of HIV, together with prompt treatment among those diagnosed, are key to ending HIV transmission by 2030.

"You can benefit from life-saving HIV treatments if you are diagnosed with HIV and it also means you cannot pass the virus on.

"HIV and STI tests are still available through sexual health clinics during the COVID pandemic. Many clinics offer online testing throughout the year -- people can order tests on clinic websites, take them in the privacy of their own home, return by post and receive results via text, phone call or post."