Covid-19 Australia: new more transmissible variants BA.4 and BA.5, cases increase
Two “more transmissible” variants of Covid-19 landed in Australia in time for winter as health experts warn of the increase in the number of cases.
If you’re wondering why Covid has been particularly effective in taking down your friends and family over the past few weeks, chances are they’ve stumbled upon another new – two – sub-variants of Omicron.
Named BA.4 and BA.5, both strains were first identified in South Africa earlier this year and have since spread around the world like wildfire.
They are more infectious than the previously dominant variants of Omicron BA.2.12.1 and BA.2 and accounted for 13% of new cases in the United States alone last week, compared to 7.5% of cases the week before.
Experts have predicted that BA.4 and BA.5 will become the dominant strains in Australia this winter and believe that both have already made a considerable contribution to the number of daily cases.
“Infection with earlier subvariants offers some protection from infection with these later variants, but reinfection is still possible,” said Catherine Bennett, Deakin University President in Epidemiology. The Daily Telegraph.
“[They’re] just a little more transmissible again than Omicron’s previous sub-variants and this helps keep our numbers high.
“It made this wave longer.”
Despite the higher rate of infection, early signs show that neither BA.4 nor BA.5 cause more severe disease than previous Omicron variants.
So far, more than seven million Australians have had some form of Covid-19.
However, Professor Bennett noted that actual case numbers could be up to double the official figures.
“If each new infection were in a new person and ignoring repeated infections, more than a quarter of the population would have had an infection,” he said.
“Given the number of cases lost – no symptoms, not tested, tested but had a false negative or tested positive on a RAT but did not report it – it is likely that at least half of the population has been infected at least once.”
Professor Bennett echoed other experts’ requests for Australians to prioritize their third vaccine, limit time in crowded spaces, wear masks indoors, and practice good hygiene.
Professor Peter Richmond, head of the vaccine testing group at the Telethon Kids Institute, further reiterated the importance of getting a booster and warned that infection rates could increase during the winter.
“Having a third dose of the vaccine is the best way to protect yourself, but if you only had two doses over six months ago, you now have very little protection,” he said.
The virus is largely set to become seasonal, with numerous federally funded studies examining the most effective strategies for launching booster vaccines.
This could be good news for long-term immunity.
“[Covid] it now appears to be underway, with Omicron helping itself to remain the dominant variant by bolstering our immunity to other variants, while still being able to cause repeat infections, ”said Professor Bennett.
However, he warned that there may be a trend towards cases “[rising] again in winter when immunity has decreased… and transmission is more efficient when we move inside ”.