Each new dominant coronavirus variant raises questions. Are people more at risk of getting sick? Will the current vaccines still work? Are there new or different things I should do now to stay safe? Let's find out what we know about the new Omicron subvariants.
What are the new Omicron subvariants?
There are two new subvariants of the Omicron strain called BA.4 and BA.5. They are spreading quickly and taking over from the Omicron subvariant BA.2. To date, these subvariants have been the most common source of infections in rising cases.
Early data suggests both subvariants have arisen from the BA.2 subvariant and not the BA.1 subvariant. But it’s still early days.
Are they more contagious?
The BA.4 and BA.5 Omicron subvariants are becoming the predominant strains. They are taking over from the BA.2 subvariant. This suggests they are more contagious.
It could also be that, as a community, we have become more immune to the previous BA.2 subvariant than we are against the new subvariants.
Do our current vaccines protect against these variants?
Concerningly, researchers have found the new subvariants are more than four times more resistant to antibodies from vaccinated and boosted people when compared to the previous BA.2 variant.
This means that even if you are up-to-date on your boosters, you might still contract the virus. But the boosters will still help protect you from severe illness.
Vaccines against Omicron are in late-stage clinical trials. They will likely to be registered for use in coming months. Recent data from Moderna has shown its Omicron vaccine protects against all Omicron subvariants. However, the antibody responses are stronger against BA.1 than the BA.4 and BA.5 subvariants.
Are all new variants more contagious than the previous ones?
It might seem like each new subvariant is worse than the last. But it’s not that simple. Often new variants and subvariants emerge without detection. Or they aren’t more contagious or severe than current dominant strains. These strains typically disappear quickly.
Although many different mutations exist, only the ones that show a competitive advantage are recorded as new strains. The others die out and are not of significant interest.
How do the new variants affect cases, symptoms and hospitalisations?
So far, the new Omicron subvariants have not shown any increase in disease severity in the UK or South Africa. However, the incidence of severe disease and hospitalisation can be closely linked to the immunity of the population. This means the proportion of vaccinated and boosted people can lead to higher or lower rates of serious illness.
Should we be worried about these variants?
This third Omicron wave should not be of any greater concern than the previous waves. But any surge in cases will cause more hospitalisations and deaths.
Plus, people who have recently recovered from COVID-19 are being reinfected by the new strains. This is frustrating for those suffering symptoms again.
In the Southern Hemisphere, the rapid spread of these subvariants during the current influenza season will make this wave more difficult to manage. And co-infection with both viruses can lead to worsened disease.
The best thing we can do to protect ourselves right now is make sure our vaccinations and boosters are up-to-date.
How prevalent are these variants in Australian cases?
The numbers are changing quickly. The BA.4 and BA.5 subvariants appear to have become the dominant strains in NSW. Wastewater catchments have shown an increase from five to 40 per cent of BA.4 and BA.5 subvariants. And we expect there will be an increase in cases in Australia driven by these new subvariants.
Do RAT and PCR tests still pick up the new variants?
Yes, the PCR test can still detect the new Omicron subvariants.
Research shows the S gene (the gene for the spike protein) is not detected in one of the PCR tests for those infected with the BA.4 and BA.5 Omicron subvariant. But PCR tests typically look at multiple genes.
Some testing labs have reported that for BA.4 and BA.5 one particular PCR test experiences what is known as 'S gene drop out'. This is where the test fails to detect the S gene, but does detect the others. Additional gene sequencing has confirmed this is a way of rapidly detecting these subvariants.
With a RAT (rapid antigen test), BA.4 and BA.5 can be detected and there is no evidence on any potential drop in accuracy.
In good news, our researchers have developed a faster and more comprehensive way to identify emerging COVID-19 variants. They do this by analysing the RNA of the whole variant, rather than the current method of monitoring changes to the spike protein.