Simon Collins, HIV i-Base
At the end of December, several leading London sexual health clinics used social media to report significant drops in number of gay men who were diagnosed HIV positive during 2016.
These preliminary data are based on early reviews. A similar number of tests were run each year and a similar number of STIs were reported for each period. This suggests that increased use of PrEP together with early diagnosis and early ART are likely to explain much of the difference.
On 22 December, the 56 Dean Street clinic reported a 40% drop from 626 HIV diagnoses in gay men during 2015 to 373 in 2016 on their FaceBook page. Figures are for January to November for each year. 
The following day, using Twitter, the Mortimer Market Centre reported a 50% drop in HIV diagnoses from January to September 2016 compared to figures from the previous year and Homerton Sexual Health services reported a 40% reduction. [2, 3]
A few days later, on 28 December, Barts Sexual Health tweeted that HIV diagnoses in gay men at this clinic had dropped by 36% in 2016 compared to 2015. 
If confirmed, these results would be unprecedented: for the last 15 years, annual UK HIV incidence in gay men has either been stable or steadily increased. The lack of change in STI rates during 2016, indicates that decline in HIV is not from changing sexual behaviour linked to HIV risk but more likely to be related to increased protection against HIV specifically – notably from PrEP and earlier use of HIV treatment.
- Several hundred men at London clinics would have been using PrEP as part of the PROUD study, after early results in October 2014 offered PrEP to all participants. 
- Community activists, motivated by the slow pace of NHS bureaucracy, publicised the option to buy generic PrEP easily and cheaply online (6, 7, 8]
- Several NHS sexual health clinics (including 56 Dean Street, Mortimer Market and Bart’s) developed new PrEP services to offer the free monitoring tests for people using generic PrEP.
- HIV treatment increasingly became routinely available for anyone diagnosed HIV positive. The risk of sexual HIV transmission is effectively zero once someone is stable on effective treatment. 
The Dean Street clinic, accounts for approximately half of HIV diagnoses in gay men in London, reported that 50% of their cases were in men whose were recently infected (within four months). This is when someone is most infectious and early treatment (now routinely offered at the clinic) dramatically reduces transmission risk to close to zero.
PrEP is more than 99% effective when taken as either a daily or on-demand dosing. Greater access to PrEP during 2016 makes the reports of reduced HIV incidence seem more than just a coincidence. Early diagnosis and early treatment are likely to have had just as much impact.
Over the same period NHS England blocked all attempts to provide PrEP and, by wanting further research, now proposes to further delay when doctors might be able to prescribe PrEP by at least another three years. 
NHS England still stubbornly sticks to a commissioning guidelines that HIV treatment should be delayed for years until significant immune damage has occurred. Luckily, HIV treatment can be prescribed if a someone want to reduce the risk to their partners.
These results are more significant than those produced by any prospective UK HIV reduction programme this century.
That this was largely accomplished without formal support from NHS England – these clinics developed their own programmes – should force a national change in approaches to sexual health.
- 56 Dean Street Facebook page. Posts and comments. (22 December 2016).
- Mortimer Market. So, joining @56deanstreet and @HomertonSHS we have also seen big decreases in new HIV diagnoses in 2016. More than 50% drop! Wow!! #EndHIV. Twitter. (23 December 2016)
- Homerton Sexual Health Services. Our new #HIV diagnoses this year in gay/bi men down by a whopping 40% #EndHIV #SexualHealth #Hackney. Twitter. (23 December 2016).
- BHSexual Health. Barts Health Sexual Health have seen a 36% drop in new #HIV diagnoses in MSM in 2016 compared to 2015, similar to other London clinics. (28 December 2016).
- UK PROUD study to provide PrEP to all participants earlier than expected: planned follow-up to continue to two years. HTB December 2014.
- IWantPrepNow community website
- Prepster community website.
- i-Base. Guide to PrEP.
- ZERO: no linked HIV transmissions in PARTNER study after couples had sex 58,000 times without condoms. HTB August 2016.
- NHS England fudges PrEP access and delays on-demand access to PrEP by years; blocks doctors from prescribing PrEP now. HTB (4 December 2016).