Australia’s Covid-19 deaths are at the lowest levels observed since December 2021, with fewer hospitalisations and intensive care admissions – despite fewer people receiving a booster vaccine this year.
“The improvements in 2023 are likely to be the combined result of high levels of vaccination coverage, hybrid immunity, and ready access to oral antiviral treatments for those who need them,” a Department of Health spokesperson said.
Australia’s fifth Covid wave, spread largely due to the XBB Omicron subvariant, began in March 2023, but was not as severe as the previous wave.
Cases in hospital peaked during this wave in the week ending 7 June, which saw a seven-day rolling average of 2,778 cases. This represented a 48% decrease from the fourth wave peak on 23 January 2023, when the seven-day rolling average saw 5,377 cases admitted to hospital.
Intensive care cases during winter’s fifth wave peaked in the week ending 13 June, with a seven-day rolling average of 85 cases – an 80% decrease from the January pandemic peak.
“In comparison with previous Omicron waves, the number of severe cases in the fifth wave has been lower, with a more gradual peak,” the spokesperson said.
In March, the World Health Organization (WHO) advised that only high-risk groups should receive ongoing Covid-19 booster doses because strong population-level immunity meant ongoing boosting of the general, healthy population offered little additional impact on curbing the virus.
The guide was largely in line with recommendations already in place in Australia since February, which prioritise high-risk groups. This advice has not changed.
The advice recommends a 2023 Covid-19 vaccine booster dose for adults aged 65 years and over, and for adults aged 18-64 years who have medical comorbidities that increase their risk of severe disease, or who have a disability combined with significant health needs.
“Communication has a particular focus on reaching priority and vulnerable audiences and seeks to connect people with credible information sources,” the spokesperson said.
“There has been a strong uptake in boosters for the 65+ cohort.”
Across the general population, however, fewer people have received a Covid-19 booster this year than previously.
The latest available data to 9 August shows 3,764,447 booster doses have been administered in 2023, though this data includes people who may have received multiple boosters throughout the year. By comparison, as of 9 August 2022, 14,136,622 people had received a booster, though this includes data back to when boosters were first rolled out in November 2021.
While the new BA.2.86 variant – which some scientists have nicknamed “Pirola” – has made headlines in recent weeks, many variants throughout the pandemic have failed to take hold despite being highly mutated.
BA.2.86 is one of many “variants under monitoring” by WHO, which just means that although it has an unusually large number of mutations, it is not possible yet to estimate whether these will cause it to spread more easily or lead to more severe disease.
If a variant has enough genetic changes to increase transmissibility, virulence and antibody evasion, and to decrease susceptibility to therapeutics, and if it is also shown to have a growth advantage over other circulating variants, only then is it upgraded to a “variant of interest”.
The next step up is a “variant of concern”, which is when a variant has made enough concerning evolutionary steps to require major public health interventions.
In the period between 17 July 2023 and 13 August 2023, the majority of sequenced cases in Australia were the Omicron XBB subvariant and its sub-lineages.
Prof Stuart Turville, a virologist at the Kirby Institute, said the media needed to be mindful about when to report on variants.
“I always liken these conversations with setting off flares,” Turville said. “If we set off too many, will we have any left when a variant of concern arrives and if we do, will anyone notice?”
