The Times Australia
The Times World News

.

What can we expect from this latest COVID wave? And how long is it likely to last?

  • Written by James Wood, Associate Professor, epidemiological modelling of infectious diseases, UNSW Sydney
What can we expect from this latest COVID wave? And how long is it likely to last?

Australia is now mid-way into its fourth wave of COVID in the Omicron era, driven by a rich soup of Omicron descendants. Unlike previous waves, where a single new variant of SARS-CoV-2 variant such as BA.2 or BA.5 was responsible, we have had an explosion of new variants[1] such as XBB.1, BQ.1.1 and BR.2.1.

Read more: From Centaurus to XBB: your handy guide to the latest COVID subvariants (and why some are more worrying than others)[2]

However, despite this apparent diversity, these new variants all follow a similar script, where the same set of changes have evolved independently across multiple variants. This is called convergent evolution.

These changes make the virus better at infecting people with immunity to existing variants. Since mid-October, the subvariants’ ability to escape immunity from vaccination and/or previous infection has been potent enough to cause a new wave in Australia.

The graph below shows the series of 2022 waves, with the original Omicron the first wave, followed by the double-bump BA.2 (where Western Australia had different timing), the winter BA.5 wave, and now a new upswing in November.

Johns Hopkins University CSSE COVID-19 Data, CC BY[3][4] In some good news, this wave is likely to be a shorter and smaller version of the BA.5 wave. Here’s why. Cases are rising rapidly In Australia, the wave is already growing rapidly, with indicators such as recorded cases and hospital occupancy[5] showing significant increases in multiple states over the last two weeks. New South Wales reports on the trend in the underlying variants[6], with a clear shift since early October. Removal of mandatory reporting and isolation has led to fewer rapid antigen tests (RATs) being reported. So we may only be recording a smaller fraction of all community infections now than in previous waves. Read more: Previous COVID infection may not protect you from the new subvariant wave. Are you due for a booster?[7] In the graph below, I’ve used the EpiNow2 R package[8] (an open-source estimation and forecasting tool) to calculate the trend in the effective reproduction number (Rt) using NSW case data[9] since early September. Rt represents the average number of people that a single COVID case infects at a given point in time. Epidemics decline when Rt is less than 1, while epidemic growth becomes likely once Rt is above 1 and is increasingly steep as Rt rises. This is now substantially above 1 in New South Wales: Trend in the effective reproduction number (Rt) in NSW as estimated from PCR case series (produced using the EpiNow2 R package). Will the wave peak by Christmas? Lessons from Singapore I think the most likely outcome is the wave will peak by Christmas. In my own work for NSW Health, I am currently projecting a peak in NSW for the first week of December. But these predictions are uncertain because it is still difficult to estimate the level of protection against infection in our population, despite impressive near real-time laboratory science[10] that is helping to characterise this. Fortunately, despite the challenges with modelling, the recent Singapore wave can guide our expectations. Caused by XBB.1, this wave was short and sharp, peaking around October 18 and then dropping back almost to pre-wave levels[11] by November 12. Read more: XBB and BQ.1: what we know about these two omicron 'cousins'[12] Singapore has also seen a significant increase in hospitalisations[13], primarily in people aged above 70. However cumulative cases, admissions and deaths are tracking to be about half those of their BA.5 wave, with no signs of increased severity. Despite the ability of XBB.1 to evade vaccination and/or previous infection, in Singapore people with prior Omicron infections were about 75% less likely[14] to test positive in this wave than in people without recorded prior infections. Singapore has also had quite a similar COVID pandemic experience to Australia in terms of restrictions, vaccination and infection waves. One exception is that mask-wearing remains more prevalent in Singapore. People wear masks on a Singapore train Singaporeans are more likely to wear masks than Australians. Shutterstock[15] We should, however, expect some differences. Australia has about six times the resident population of Singapore with widely separated population centres. This might mean the wave duration across Australia is one to two weeks longer. Australia also has a higher proportion of the population above 75, a large fraction of whom haven’t had COVID[16] this year and therefore won’t have hybrid immunity (from both vaccination and prior infection). This could result in more hospital admissions and deaths per capita than in Singapore. But in general, the Singapore wave supports the prediction this fourth Australian wave of 2022 will peak in early December and fall back below current levels by Christmas. Is this the new normal? What can we expect in the years to come? Beyond this year, I’m encouraged by the shift in pattern from single variants causing waves to the evolving variant soup. This evolution has been very rapid recently but there are signs this may slow considerably in 2023. Firstly, the rate at which mutations occur is proportional to how much virus is circulating. The enormous number of COVID infections across this year mean that in 2022 this change has happened quickly but with each wave getting smaller, this rate of change should slow. The recent variant soup evolution may also be a positive sign. The different variants in the soup have all gained a transmission advantage following the same immune-escape strategy. The set of relevant mutations were in fact predicted in advance by researchers at the University of Washington. If you are infected with one of these new variants, you should also have strong protection to the rest of the soup. The absence of big mutational jumps in dominant variants suggests SARS-CoV2, the virus that causes COVID, may now be entering a period of slower, more continuous evolution. This is what we see for seasonal influenza[17]. COVID has been full of surprises but the evidence suggests we could see SARS-CoV-2 infections fall below our recent trough levels in 2023 and the beginning of a more seasonal pattern to COVID waves. Read more: Why haven't I had COVID yet?[18] References^ new variants (www.health.nsw.gov.au)^ From Centaurus to XBB: your handy guide to the latest COVID subvariants (and why some are more worrying than others) (theconversation.com)^ Johns Hopkins University CSSE COVID-19 Data (ourworldindata.org)^ CC BY (creativecommons.org)^ recorded cases and hospital occupancy (www.health.gov.au)^ trend in the underlying variants (www.health.nsw.gov.au)^ Previous COVID infection may not protect you from the new subvariant wave. Are you due for a booster? (theconversation.com)^ EpiNow2 R package (github.com)^ NSW case data (data.nsw.gov.au)^ near real-time laboratory science (www.biorxiv.org)^ pre-wave levels (www.moh.gov.sg)^ XBB and BQ.1: what we know about these two omicron 'cousins' (theconversation.com)^ significant increase in hospitalisations (www.moh.gov.sg)^ 75% less likely (www.moh.gov.sg)^ Shutterstock (www.shutterstock.com)^ haven’t had COVID (kirby.unsw.edu.au)^ what we see for seasonal influenza (www.cdc.gov)^ Why haven't I had COVID yet? (theconversation.com)

Read more https://theconversation.com/what-can-we-expect-from-this-latest-covid-wave-and-how-long-is-it-likely-to-last-194444

Times Magazine

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

From Beach Bops to Alpine Anthems: Your Sonos Survival Guide for a Long Weekend Escape

Alright, fellow adventurers and relaxation enthusiasts! So, you've packed your bags, charged your devices, and mentally prepared for that glorious King's Birthday long weekend. But hold on, are you really ready? Because a true long weekend warrior kn...

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Science Behind Reverse Osmosis and Why It Matters

What is reverse osmosis? Reverse osmosis (RO) is a water purification process that removes contaminants by forcing water through a semi-permeable membrane. This membrane allows only water molecules to pass through while blocking impurities such as...

Foodbank Queensland celebrates local hero for National Volunteer Week

Stephen Carey is a bit bananas.   He splits his time between his insurance broker business, caring for his young family, and volunteering for Foodbank Queensland one day a week. He’s even run the Bridge to Brisbane in a banana suit to raise mon...

The Times Features

My shins hurt after running. Could it be shin splints?

If you’ve started running for the first time, started again after a break, or your workout is more intense, you might have felt it. A dull, nagging ache down your shins after...

Metal Roof Replacement Cost Per Square Metre in 2025: A Comprehensive Guide for Australian Homeowners

In recent years, the trend of installing metal roofs has surged across Australia. With their reputation for being both robust and visually appealing, it's easy to understand thei...

Why You’re Always Adjusting Your Bra — and What to Do Instead

Image by freepik It starts with a gentle tug, then a subtle shift, and before you know it, you're adjusting your bra again — in the middle of work, at dinner, even on the couch. I...

How to Tell If Your Eyes Are Working Harder Than They Should Be

Image by freepik Most of us take our vision for granted—until it starts to let us down. Whether it's squinting at your phone, rubbing your eyes at the end of the day, or feeling ...

Ways to Attract Tenants in a Competitive Rental Market

In the kind of rental market we’ve got now, standing out is half the battle. The other half? Actually getting someone to sign that lease. With interest rates doing backflips and ...

Top Tips for Finding the Ideal Block to Build Your Home

There’s something deeply personal and exciting about building your own home. You’re not just choosing paint colours or furniture, you’re creating a space that reflects your lifes...