Australia has recorded the lowest number of new HIV diagnoses in a year since 1984, but doctors are concerned a high proportion of people are being diagnosed late in their infection.
Data published by the Kirby Institute on Wednesday shows 633 HIV cases were recorded in 2020, a substantial drop from the 901 diagnoses in 2019.
Cases have been declining in Australia since 2015 thanks to a combination of prevention measures, treatment and testing, though experts believe the particularly stark drop last year is due to Covid-19 restrictions.
The epidemiologist Dr Skye McGregor, who heads the Kirby Institute's public health surveillance innovation group, said with social restrictions in place "people have been having less sex and were less likely to go and get tested".
"There has also been less travel in and out of Australia," she said. "Nevertheless, these low numbers are good news and should be celebrated."
The chief executive of the Australian Federation of Aids Organisations, adjunct professor Darryl O'Donnell, said elimination was "entirely achievable with political will and investment".
"It will deliver a remarkable health achievement while also saving taxpayers billions of dollars in long-term costs," he said.
The Kirby data shows a substantial reduction in cases among gay and bisexual men, from 765 in 2016 down to 426 in 2020. Each year, a greater proportion of new HIV cases are attributed to heterosexual sex, and McGregor said further prevention strategies would need to target this group.
In 2020, 67% of cases were attributed to sex between gay and bisexual men, while 24% were attributed to heterosexual sex. The remaining cases were attributable to injecting drug use and other exposures, with needle and syringe programs including safe injecting rooms helping to maintain low cases in this group.
However, 44% of people diagnosed with HIV in 2020 were considered "late diagnoses" - meaning they had been living with the infection for four or more years without knowing it.
"Without treatment, a person's immune function can deteriorate and they will become immunocompromised and may end up in hospital, so delayed diagnosis and treatment is not ideal for an individual's health," McGregor said.
"If they are unaware they have HIV they may unknowingly pass on the infection to someone else. Thus regularly testing and early treatment is key to controlling HIV."
People living with HIV who take their medication as prescribed can maintain an undetectable viral load, which means they have effectively no risk of transmitting the virus to others. It makes early treatment a crucial part of preventing new HIV cases.
There were 18 new HIV diagnoses in Aboriginal and Torres Strait Islander people in 2020, representing a 28% reduction since 2019. However, with small numbers, caution needs to be taken when interpreting the results.
Kirby's manager of Aboriginal and Torres Strait Islander health research, Robert Monaghan, said sustained and culturally appropriate prevention efforts were needed to eliminate HIV in Indigenous communities. "It is especially important that these programs are maintained alongside Covid-19 prevention programs," he said.
While the declines are promising, McGregor said eliminating transmission in Australia would mean investing in access to a range of effective prevention options, including pre-exposure prophylaxis (taking HIV treatment to prevent infection in the first place), early treatment of new cases, and high HIV testing rates.
"We also need to ensure continued efforts to reduce stigma and discrimination," she said. "In combination, this will help Australia to achieve elimination of HIV transmission."
On Wednesday, which is World AIDS Day, the health minister Greg Hunt announced more than $50m in new funding to improve access to HIV treatment and to support the health and mental wellbeing of people living with blood borne viruses and sexually transmissible infections.
"This investment will benefit an estimated 1,000 people currently living with HIV in Australia each year, providing access to appropriate and equitable HIV treatment and care," Hunt said.
Access to new testing has also been made possible through recent changes by the Therapeutic Goods Administration to increase the availability of the Atomo HIV Self-Test, the only HIV self-test approved for sale in Australia.
