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New variants expected to supplant BA.5 in Australia


Matt Woodley


31/10/2022 4:43:48 PM

Both XBB and BQ.1 possess a growth advantage over previous COVID strains, but there is no evidence to suggest either variant is more severe.

Graphic representing COVID mutation.
XBB and BQ.1 have now been detected in several parts of Australia.

Health authorities have warned Australia is at the start of another COVID wave, following the arrival of two new variants that can more easily escape immunity from past infection and vaccination.
 
XBB and BQ.1 have now been detected in New South Wales, Victoria and Western Australia, while cases and hospitalisations are also beginning to increase after months of declines.
 
The variants have already attracted substantial attention overseas as they appear to be quickly supplanting BA.5, despite its own growth advantages over previous strains.
 
In Singapore, it only took three weeks for XBB to ‘outcompete’ every other variant present on the island, generating a new COVID wave in the process, while BQ.1 has been detected in at least 65 countries and is rapidly gaining a foothold in Europe.
 
In Victoria, hospitalisations increased by 20% in the week leading up to 28 October, prompting a warning for people to ensure they are taking appropriate disease mitigation steps such as vaccination, self-isolating when symptomatic, and wearing masks.
 
‘Surveillance shows the … rapid growth of BQ.1 and XBB in the past month, with a combined prevalence of approximately 10% in wastewater and clinical samples,’ the most recent Victorian Chief Health Officer update states.
 
‘Continued growth at these rates would see these subvariants overtake BA.5 as the dominant variant.
 
‘The increase in cases and hospitalisations, combined with an increase in the PCR positivity rate and antiviral prescriptions [up 8% in the past week] … show we are at the start of another COVID-19 wave.’
 
However, while cases are expected to increase as a result of the new variants, the World Health Organization (WHO) has resisted labelling either as a variant of concern, stating that they do not diverge sufficiently from other Omicron sublineages to warrant the designation.
 
‘While so far there is no epidemiological evidence that these sublineages will be of substantially greater risk compared to other Omicron sublineages, we note that this assessment is based on data from sentinel nations and may not be fully generalisable to other settings,’ a release from the WHO’s Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE) states.
 
‘The potential impact of these variants is strongly influenced by the regional immune landscape.
 
‘With waning immune response from initial waves of Omicron infection, and further evolution of Omicron variants, it is likely that reinfections may rise further.’
 
Deakin University epidemiologist Professor Catherine Bennett has also moved to ease concerns, telling News Corp Australians will have stronger hybrid immunity to new variants compared to when Omicron and Delta sparked major waves in 2021.
 
‘More than half the population has been both vaccinated and had an infection, and that does put you in a more resilient position in when facing future waves,’ she said.
 
Australia will also have some access to new bivalent vaccines that are slightly more effective against Omicron variants compared to those that target the original strain.
 
While it is not known how many Moderna bivalent vaccines will arrive before the end of the year, the Therapeutic Goods Administration (TGA) has now also provisionally approved Pfizer’s bivalent candidate for use as a booster.
 
A Department of Health and Aged Care spokesperson told newsGP access to the bivalent vaccine is included as part of the supply agreement signed with Pfizer for 2022 and 2023, and that it will work ‘closely’ with the company to secure some by the end of the year.
 
However, they would not confirm how many vaccine doses the Government has ordered, received or administered by vaccine type or brand, citing contractual arrangements.
 
It is not clear why contractual arrangements now preclude the sharing of this information, which was routinely provided during the first two years of the pandemic.
 
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BA.5 BQ.1 COVID-19 Omicron XBB


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