“In the war against any infectious virus,” says Dr Alan McOwan, “You’re trying to win various battles. You have to keep clobbering it from every direction you can.” That’s true for coronavirus, he says, as well as for other viral conditions. An HIV specialist at London’s 56 Dean Street sexual health clinic, McOwan sees similarities between Covid-19 and HIV. Both are viruses without a working vaccine, you can be infectious without knowing it, and both rely mostly on close human contact to spread. McOwan and his colleagues are not only interested in comparing the two viruses, but also in examining their interplay. Because while the spread of all infectious diseases, Covid included, is slowed by physical distancing, sexual health specialists believe the unique set of circumstances lockdown has created offers an unprecedented opportunity in the decades-long fight against HIV too. Since the run-up to the lockdown, clinicians at 56 Dean Street have closely monitored their new cases of gonorrhoea and prescriptions written for post-exposure prophylaxis (PEP), a treatment which, if taken within 72 hours of exposure to HIV, can stop the virus taking hold. On both fronts they have seen sharp declines. “We chose these two markers as they are things people would tend to not put off coming in for,” says McOwan. “If you have gonorrhoea in your penis, it feels like you’re peeing razor blades and you may have discharge within four to seven days. To be effective, PEP needs to be taken quickly.” Their findings confirmed what health professionals nationwide had predicted: through complying with measures to physically distance, the public are having less “risky” unprotected sex with new partners. This alone has helped slow the rate of HIV transmission, but a prolonged period of sexual inactivity in Britain has other benefits in the attempt to slow new cases of HIV. People are most infectious in the earlier stages of contracting HIV, and therefore more likely to pass it on. Ordinarily, the viral load of HIV-positive people not on treatment is counted in the tens of thousands, while the figure for one patient of McOwan’s who had recently contacted HIV was 520bn. “As very few people right now have recently caught HIV,” says McOwan. “There are far fewer of those very infectious people around.” Having already lasted seven weeks, the lockdown also mitigates one of the biggest challenges usually facing sexual health clinicians: it can take up to a month from potential exposure to HIV for current tests to return a definitive result. “If nobody has had sex which has put them at an HIV risk for at least four weeks,” says McOwan, “there will be nobody in this blindspot who might otherwise be missed.” When taking regular treatment, people who are HIV positive have an undetectable viral load and therefore cannot pass on the infection. New HIV infections had already been dropping nationally, in part because the NHS is increasing public access to pre-exposure prophylaxis (PrEP), a drug taken by HIV-negative people before and after sex that reduces the risk of getting HIV. In 2012, there were an estimated 2,800 new HIV diagnoses among men who have sex with men in the UK. In 2018 the figure was down to 800, a 71% fall. “If we can now find the remaining people with HIV through testing and put them on treatment,” says McOwan, “we could remove anyone who is infectious from the population with long-lasting effects. We won’t get this two-month window of no sex again.” Similar successes could also be seen in other locked-down countries where testing and treatment is widely accessible. The New Zealand Aids Foundation has already contacted Dean Street, asking permission to replicate its campaign. This is an opportunity, McOwan says, that he and his colleagues are determined to “grab by the balls”. Alongside the Terrence Higgins Trust and other organisations in the sector, the Dean Street team have been working to encourage anyone who might have been exposed to HIV since their last check-up to get tested before the lockdown is lifted. Their social media posts explaining how this period could “break the chain” have been their most ever shared. But this effort can only succeed if patients can access HIV testing before resuming normal sexual activity. Sexual health services are commissioned by local authorities rather than NHS England nationally, which means access to different testing methods depends on where a patient lives. Online, postal testing isn’t always routinely available in all areas, and coronavirus has seen many standard face-to-face sexual health services closed while resources are redeployed. The results of a survey conducted by the British Association for Sexual Health and HIV, published in early April, found a quarter of responding medical practitioners could not offer patients access to online HIV testing. Over half reported having under 20% of their standard capacity to deliver face-to-face HIV services. “Where it’s available online, postal testing has ramped up,” says Dr Michael Brady, a consultant in sexual health and HIV at King’s College Hospital, and medical director of the Terrence Higgins Trust. “In London, and in many other parts of the country, we have really good online testing services with capacity, but it’s not uniform. There will be places which don’t offer online testing or have a restrictive number of tests available, and there’ll be a problem if in those places face-to-face services haven’t yet opened up.” While some clinics remain closed, many NHS trusts adapted their HIV testing to introduce online services and have informed frontline healthcare workers, but some have not. When the Guardian contacted a clinic within the Northumbria NHS trust to ask whether routine HIV testing was available, it was told that this would not currently be possible in person or online. A spokesperson for the trust later added that they were offering HIV testing, and that they are addressing the fact incorrect information was being provided. A clinician within the Sherwood Forest hospitals trust in Nottinghamshire similarly said testing was not available, although a spokesperson later confirmed testing was being done online. The advice from the experts is clear: lockdown has given us a once-in-a-lifetime chance to bring down new HIV transmissions; if you belong to an at-risk group and might have been exposed to the virus since you were last tested, order a test and take it now. As it stands, however, not everyone can. And even when testing capacity is available, some clinics are apparently unaware. “The message about this unique opportunity is futile,” says Brady, “unless we ensure that postal tests are there for those who need them. If everyone is able to use their time in lockdown to test for HIV and know their status we could make significant advances towards ending HIV transmission in the UK.”