The large fall in HIV diagnoses in London gay men is real and thanks to combination prevention, not just PrEP

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The number of new HIV diagnoses in gay men attending five key London clinics fell substantially during 2015 and 2016, Valerie Delpech of Public Health England told the British HIV Association (BHIVA) conference in Liverpool yesterday.

Epidemiological analysis shows that the phenomenon is real. Diagnoses fell while testing rates dramatically increased, showing that the explanation cannot be reduced testing. The CD4 cell counts of newly diagnosed men increased, suggesting that fewer new diagnoses are indeed the reflection of fewer new infections. The time from diagnosis to starting HIV treatment has fallen.

Delpech said that the results were the result of combination prevention – testing and 'treatment as prevention'. Pre-exposure prophylaxis (PrEP) is likely to have contributed to the fall, but to a lesser extent, she said. It could have more impact in the future.


detectable viral load

When viral load is detectable, this indicates that HIV is replicating in the body. If the person is taking HIV treatment but their viral load is detectable, the treatment is not working properly. There may still be a risk of HIV transmission to sexual partners.

post-exposure prophylaxis (PEP)

A month-long course of antiretroviral medicines taken after exposure or possible exposure to HIV, to reduce the risk of acquiring HIV.


In discussions of consent for medical treatment, the ability of a person to make a decision for themselves and understand its implications. Young children, people who are unconscious and some people with mental health problems may lack capacity. In the context of health services, the staff and resources that are available for patient care.


The last part of the large intestine just above the anus.


In relation to medicines, a drug manufactured and sold without a brand name, in situations where the original manufacturer’s patent has expired or is not enforced. Generic drugs contain the same active ingredients as branded drugs, and have comparable strength, safety, efficacy and quality.

Nneka Nwokolo of the 56 Dean Street clinic agreed: “Although I think we all accept that PrEP plays some part, actually the decrease started significantly before PrEP was being used in any widespread way,” she said. The clinic quickly identifies and engages the men with the very highest risk of acquiring HIV and encourages them to attend each month for sexual health check-ups. GeneXpert testing for sexually transmitted infections has reduced the time from test to treatment from ten to two days.

Perhaps most importantly, a quarter of newly diagnosed individuals now start HIV treatment within three days of diagnosis.

Valerie Delpech said that Public Health England had reliable data on new HIV diagnoses across England up to and including the third quarter of 2016 (July to September), whereas reports for the last quarter were still coming in. Nationally, there was a clear fall in diagnoses in gay men between October 2014 and September 2016, but not in other population groups.

Moreover, there are five clinics at which the falls in gay male diagnoses were concentrated. They are all in London: 56 Dean Street (which accounts for over a third of diagnoses), the Mortimer Market Centre, Burrell Street, Homerton Sexual Health and St Mary’s.

Trends in clinics elsewhere in London, and elsewhere in England, are different.

During 2015, there were over 200 new diagnoses per quarter at these ‘steep fall’ clinics. In 2016, this lowered to between 100 and 150 diagnoses per quarter.

This has occurred against a backdrop of many more HIV tests being done and men getting tested more frequently. Among repeat testers (men who had tested at the same clinic within the previous two years), the number of tests done per quarter at the five clinics increased from around 4500 in 2013 to almost 10,000 in 2016. The greatest falls in diagnoses occurred in repeat testers, rather than men testing for the first time at that clinic.

Delpech said that clinics appeared to have got better at identifying men at greater risk of HIV (for example, those with rectal STIs and those seeking post-exposure prophylaxis [PEP]) and encouraging them to come back more often for testing. The number of men taking two, three or four tests within two years has increased dramatically. Nonetheless, around half of clinic attendees still test only once in two years.

The time from diagnosis to starting HIV treatment has been falling for several years. This has been observed across the country, but has been especially marked in recent years in the five steep fall clinics. In 2011 the median was around 450 days; in 2013, around 180 days; and in 2015, around 100 days.

As a result of both faster diagnosis and faster treatment, the estimated number of gay men with a viral load over 200 copies/ml at these clinics has fallen dramatically. There were around 4000 men in 2014, falling to around 1700 in 2016. These numbers include the estimated number of men with undiagnosed HIV infection attending these clinics, together with men not on treatment and men on treatment but virally unsuppressed.

Delpech presented data on the ‘transmissibility ratio’, a new measure which could serve as a proxy for the risk of onward HIV transmission in a clinic population and the sexual networks they connect with. It is calculated by dividing the estimated number of men with a detectable viral load by the number of men considered ‘high risk’, those with an STI in the previous year.

At the steep fall clinics, there were 1752 men with detectable HIV and 3596 men at high risk, producing a ratio of 0.5. (With a ratio below 1, the chance of transmission is low.) However, at other London clinics, there were 1444 men with detectable HIV and 868 at high risk, producing a ratio of 1.7 (suggestive of a greater transmission risk). Similarly, outside London, the ratio was 1.7.

Other clinics have seen increases in testing rates and decreases in time to starting treatment, but the changes do not appear so far to be of a sufficient scale, or combined in the same way, so as to result in the large falls in new diagnoses observed at the five London clinics.

“We are witnessing and recording an ecological experiment of the impact of combination prevention on HIV incidence,” Delpech said. While the downturn in new diagnoses has only been seen in gay men, she said that there was no reason why testing and early antiretroviral therapy (ART) could not be scaled up in all people who are at risk of HIV in this country, regardless of gender, ethnicity or sexuality.

More detail from 56 Dean Street

Two further presentations gave more details of rapid initiation of HIV treatment and of PrEP use at 56 Dean Street. This central London clinic diagnoses more people with HIV than anywhere else in the UK and was the first to report a fall in diagnoses (last December).

Responding to patient demand for immediate treatment and inspired by the San Francisco RAPID programme, the clinic increased capacity last summer to provide a medical review two days after HIV diagnosis, rather than two weeks after.

Between July and November 2016, 127 new HIV diagnoses were made. All but two were in gay men and half tested positive on the recent infection testing algorithm (RITA), suggesting HIV acquisition within four months.

Of the 127 newly diagnosed individuals, 118 came back for the medical appointment, one quarter within two days and three-quarters within 12 days. Of those, 89 began HIV treatment at that appointment.

Gary Whitlock of 56 Dean Street said that he was reassured by the 29 individuals who declined, demonstrating that patients were not being bullied into rapid treatment. In the months that followed, 26 of the 29 chose to start treatment.

Turning to people buying and importing generic PrEP drugs, the clinic provided an update on an analysis presented last October. Between February 2016 and February 2017 around 700 patients told the clinic that they were using PrEP, with data available for 371 people who attended follow-up. All were gay men.

Tests of drug levels in blood samples of PrEP users did not uncover any cases of counterfeit or fake supplies, with drug concentrations similar to those observed in studies of branded Truvada.

There were no HIV infections.


Delpech V. Towards elimination of HIV amongst gay and bisexual men in the United Kingdom. British HIV Association conference, Liverpool, April 2017.

Whitlock G et al. Rapid initiation of antiretroviral treatment in newly diagnosed HIV: experience of a central London clinic. British HIV Association conference, abstract O14, Liverpool, April 2017.

Aloysius I et al. InterPrEP (II): internet-based pre-exposure prophylaxis (PrEP) with generic tenofovir DF/emtricitabine (TDF/FTC) in London: analysis of safety and outcomes. British HIV Association conference, abstract P32, Liverpool, April 2017.