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Cases falling but the XBB.1.5 variant now detected in WA

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In WA Covid-19 cases are continuing to fall but yesterday WA Health said one case of the Omicron XBB.1.5 variant has been confirmed in the state.

The Omicron XBB.1.5 variant is a sublineage of XBB, which emerged when a person was infected with two BA.2 sublineages.

There are concerns XBB.1.5 is rapidly spreading around the world and likely to become the next dominant subvariant with the elderly and immunocompromised most at risk.

In its January 11 risk assessment the World Health Organization (WHO) said based on its genetic characteristics and early growth rate estimates, XBB.1.5 may contribute to increased cases globally.

Along with BQ.1 variants, XBB variants are the most antibody-resistant variants to date.

“Using pseudotyped virus neutralization assays, XBB.1.5 is shown to be equally immune evasive as XBB.1, the Omicron subvariant with the highest immune escape to date,’’ WHO said.

“Severity assessments are ongoing (but) XBB.1.5 does not carry any mutation known to be associated with potential change in severity.’’

More analysis is being sort from other countries where XBB.1.5 has been detected as to date the growth estimates are only from one country, the USA.

WA Health reported a total of 3690 new cases in the week to 4pm on January 19 down from 5618 new cases in the week to January 12.

The January 19 report also included 21 deaths, dating back to December 16 last year, for people aged from 69 to 99 years while the January 12 report included 23 deaths, dating back to December 10 for people aged from 72 to 97 years.

The Western Australian seven-day moving average of Covid-19 cases per 100,000 by age group from February 8 last year to January 15 this year includes data on the number of cases for people 70 and over (see graph below) but does not include deaths.

Federal Department of Health and Aged Care data shows across Australia since the beginning of the Omicron outbreak in late November 2021 up to December 17, 2022 there have been 3600 deaths in residential aged care facilities due to Covid-19.

According to Western University professor of medicine, pathology and laboratory medicine and epidemiology and biostatistics Sameer Elsayed XBB.1.5 is perceived as being equally capable of causing serious illness in elderly and immunocompromised people compared with previous Omicron subvariants of concern.

Being ‘immunocompromised’ means having a weakened immune system due to a medical condition or particular immunosuppressive medications.

Many conditions can cause immunocompromise, including cancer, especially blood cancer (leukaemia or lymphoma), treatments for cancer (e.g. chemotherapy, targeted therapies transplants or CAR-T cell therapy), immune deficiency syndromes and HIV infection (if the CD4 count is low).

Writing in The Conversation on January 17 Professor Elsayed said the highly transmissible, extensively drug-resistant and profoundly immune system-evading XBB.1.5 was rapidly spreading across the globe and would likely become the next dominant subvariant SARS-CoV-2 subvariant.

On January 11 OzSAGE – a multi-disciplinary network of Australian experts from a broad range of sectors formed in response to the current Australian epidemic – said Covid was now the third highest cause of death in Australia and indications were that unless Australia changed its stance on managing Covid the trend would continue into 2023.

Professor Elsayed said antiviral medicines such as remdesivir and Paxlovid could be considered for the treatment of eligible infected patients at high risk of progressing to severe disease.

“Standard infection control precautions including indoor masking, social distancing and frequent handwashing are effective measures that can be employed for personal and population protection against XBB.1.5 and other subvariants of concern,’’ he wrote.

“Although bivalent boosters may be considered for elderly, immunocompromised and other risk-averse individuals, their effectiveness in preventing Covid-19 illness due to XBB.1.5 remains uncertain.’’

OzSAGE said recently the majority of hospitalisations and deaths were in unvaccinated people or those that have only received two doses of vaccine.

After its November 11 meeting the Australian Technical Advisory Group (ATAGI) said it continued to review the role of booster doses in the Covid-19 vaccination program.

“New booster dose recommendations are anticipated in early 2023 in preparation for winter,’’ their statement said.

“Future recommendations will aim to provide ongoing clear guidance across all groups including time since last dose and definitions of eligibility.”

This article appeared on Yanchep News Online on 22 January 2023.


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