Gay men who defied medical advice seem to have changed the course of the HIV epidemic in the UK – for the better.

Four London sexual health clinics saw dramatic falls in new HIV infections among gay men of around 40 per cent last year, compared with 2015, new figures show.

This decline may be mostly due to thousands of people buying medicines called pre-exposure prophylaxis (PrEP), which cut the chance of catching the virus, online.

“We need to be very cautious at this stage, but I can’t see what else it can be,” says Will Nutland at the London School of Hygiene and Tropical Medicine, who has set up PrEPster, a website that gives people information on how to give themselves PrEP. “Something extraordinary has happened in the last 12 months because of a bunch of DIY activists working off our kitchen tables.”

The medicine has been approved in the UK as a drug for preventing HIV infection in both men and women, but it isn’t yet available on the National Health Service.

“People say, ‘Why don’t gay men just use condoms?’,” says Mags Portman of the Mortimer Market Centre in London, one of the clinics that has seen large declines in diagnoses. “They do, but not all the time. Straight people don’t use condoms all the time either.”

To avoid paying £400 a month for private prescriptions of the brand-name drug Truvada, growing numbers are buying generic versions from online pharmacies in India and Swaziland for £40 a month, through a UK website called I Want PrEP Now.

International drugs

Until recently, most doctors would have advised against buying any medicines online, warning that the process could be illegal or the drugs may not be safe. While it is legal to buy up to a three-month personal supply, it can seem shady as the medicines are sent through several countries to get around custom laws.

But attitudes are changing. Some sexual health doctors now help people who source PrEP online by providing blood tests to check the pills are real and urine tests to ensure people aren’t getting kidney damage as a side effect. So far no pills have turned out to be fake.

These doctors were also reassured when the regulatory body, the General Medical Council, told them its ethical guidelines say clinicians should give patients information about treatments they cannot offer themselves, says Portman.

The rise of PrEP

PrEP use has been rising in other countries, and some cities have also seen drops in new HIV diagnoses. San Francisco saw a 17 per cent fall in infection rates in 2015.

But this decline has generally been attributed to a mix of better prevention, diagnosis and treatment methods, without singling out PrEP. Higher rates of diagnosis and treatment cut new infections because HIV drugs slash the amount of virus in people’s genital fluids, lowering the risk of passing it on to almost zero.

In the UK, however, the use of PrEP was low until it suddenly surged over the past year. This increase coincided with the launch of I Want PrEP Now and PrEPster, and ongoing publicity over an attempt to sue NHS England to provide the medication on the NHS.

Greg Owen, who runs I Want PrEP Now, estimates that more than 2000 people buy it through his non-profit site. Doctors mainly recommend that people use his site rather than finding a manufacturer to buy from directly because Owen works with NHS clinics to check the medicines are genuine.

Some people also manage to get free PrEP through the NHS by claiming they were exposed to HIV through unprotected sex in the past few days. This gets them a month’s worth of pills and the supply can be continued by “clinic hopping”: attending different hospitals every month using false names.

Cat’s out of the bag

The falls in new HIV diagnoses among gay men at the four London health centres were announced last month. While it is unknown how much of this is thanks to PrEP, several doctors say it is probably the main factor. “We are convinced that PrEP is responsible for the large decreases in new diagnoses,” Portman said in a tweet about the announcement.

While a similar drop is unlikely to be seen in total HIV infections across men and women, the decline among gay men is important. Just over half of new UK infections are in gay men, so such a drastic drop could significantly slow the epidemic.

Sheena McCormack of the London clinic 56 Dean Street says the fall in infection rates is unlikely to be due to more condom use, as rates of other sexually transmitted diseases such as syphilis were about the same in 2016 as the year before.

Matthew Hodson of the HIV information charity NAM says that while the drop could in theory be down to the preventative impact of wider testing and treatment, that is unlikely because of the timing and steep decline in incidence.

The best argument for using PrEP is that it works so well at reducing new infections, says Jason Domino, who has been using the medicine for two years, after a scare when a partner turned out to be HIV-positive. “You’re tackling an infection that’s hugely expensive to address,” he says. “It saves the NHS money.”

But a Public Health England spokesperson told New Scientist that a range of other factors could have caused the fall in new HIV diagnoses. After NHS England lost a court case in November, Public Health England said it would make PrEP available, but only as part of a 10,000-person trial to answer outstanding questions about how the drug should be rolled out.

“The NHS needs to pull its finger out and make sure there’s a contingency plan for what to do when its 10,000 places fill up,” says Nutland. “The cat is out of the bag that PrEP really works.”