Ideasroom

Actions to eliminate Covid-19 could work for HIV

As NZ adapts to measures to limit the Covid-19 pandemic, the time is right to test and treat those who have HIV but don't know it, says Peter Saxton.

Physical distancing is working. Few new Covid-19 cases signals we’re on track to eliminate transmission of SARS-CoV-2 in New Zealand.

If we’ve successfully mobilised against a novel coronavirus, what about established infectious diseases? HIV is a tantalising candidate because both viruses thrive on human contact patterns. Dismantle those contact patterns and you disrupt viral spread. And lockdown has pulled the handbrake on casual sex like no other period in Aotearoa’s history. Ever. 

Take a moment to reflect on our social experiment. The border is closed. Physical distancing is enforced. Public compliance has been extraordinary. Unfathomable in peacetime, these unique conditions present us with a once in a lifetime opportunity to stamp out not one but two major infectious diseases.

HIV and Covid-19 already have us invoking familiar concepts. Asymptomatic infection, duration of infectiousness, modes of transmission, behaviour change, DNA and antibody testing, chains of transmission, contact tracing, case surveillance, sentinel surveillance, clusters, vaccine development, treatment research, pre-exposure prophylaxis (PrEP), social marketing campaigns, scapegoating and even stigma have become a shared lexicon.

For both viruses, the impact on communities within society has been uneven. Interventions have been both universal and targeted. Tough decisions have allocated scarce health resources. Tensions have exposed underlying prejudices. We’re reflecting on individual preferences, personal sacrifices, values, intimacy and privacy. We’re discussing the ripple effect our choices can have on others, and vice versa. We’re debating the nature of shared interests in a communicable disease epidemic, and the role (and limits) of altruism and cooperation.  

But we should heed crucial differences in HIV and Covid-19. First, in vectors of transmission: sexual intercourse is not sneezing. Sexual partnerships require closer contact, are less frequent and simpler to contact trace than social ties. This means containing HIV is easier short term (with adequate resources).

Secondly, in the duration of infectiousness: HIV is lifelong in the absence of antiretroviral treatment; SARS-CoV-2 ceases within 14 days. HIV is especially infectious to others in the early acute phase lasting a few weeks to months. So, unlike undiagnosed Covid-19, where most cases resolve during physical isolation, people living with undiagnosed HIV will emerge from lockdown still very much infectious.

Thirdly, in diagnostics: the combined fourth generation HIV antibody and antigen tests are among the most accurate in medicine at 99 percent sensitivity and specificity, whereas currently Covid-19 PCR tests are around 70 percent sensitive. It’s true that HIV tests might not detect very recent infections, but there will be very few new HIV transmissions happening during lockdown. HIV tests are therefore reliable and will miss few positive cases.

Fourthly, in treatment and prevention: Once diagnosed, people living with HIV can be offered antiretroviral treatments that keep them healthy and will make them sexually uninfectious. This creates a considerable incentive for at-risk individuals to test for HIV. In contrast, we can’t yet offer effective Covid-19 treatment. For some individuals, the prospect of quarantine creates disincentives to test. 

Finally, in the targets for testing: although HIV and Covid-19 can affect anyone, in New Zealand, HIV transmission is concentrated among gay and bisexual men. We’ve estimated that gay and bisexual men are 187 times more likely to be living with diagnosed HIV compared to heterosexual kiwis. Our 2011 study in Auckland gay community settings found that 1 in 5 of those with HIV were unaware; overall 1.3 percent of gay and bisexual men had undiagnosed HIV. In today’s numbers, this represents around 700 individuals living with undiagnosed HIV.

The challenge now is to diagnose everyone who’s unaware they have HIV, so they can benefit from treatment and not be infectious to others. Then we could literally emerge from our bubbles with no infectious HIV circulating in New Zealand, the same goal we have for Covid-19.

Obviously, we want to do this without swamping our busy health system that’s rightly focused on Covid-19. We could scale up home HIV testing (like the NZ AIDS Foundation just has), HIV testing in the community, point of care HIV testing. When people visit their GP, we could double-up Covid-19 testing and flu vaccinations with HIV tests and tests for other sexually transmitted infections for at-risk individuals. These innovations might also improve equity, as Māori gay and bisexual men living with HIV face barriers getting diagnosed promptly. Right now, our health professionals and community workers are accustomed to caring for people who feel nervous and vulnerable about Covid-19; people at risk of HIV often feel the same.

Ideally, we want people to emerge from Covid-19 alert levels knowing their HIV status, and variously being on HIV treatment, using HIV PrEP, using condoms or other risk-reduction approaches.

The climate is ripe for stamping out these dual epidemics. The Covid-19 crisis has forced us to re-imagine what’s possible, not only for public health, but for the relationship between society and the state. Acting now is truly an investment in all our futures.

Sunday 17 May is the International AIDS Candlelight Vigil. The memorial has moved online due to COVID-19 restrictions.

Dr Saxton’s HIV prevention research has been funded by the Ministry of Health, Health Research Council, New Zealand AIDS Foundation and PHARMAC.

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