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New Covid subvariants BA.4 and BA.5 are the most contagious yet, which will take over in NSW

The latest variants are masters at evading immunity – meaning previous infection and vaccines are unlikely to provide much protection against catching i

New variant BA.4 and BA.5 NSW

According to the Guardian, Australia is heading for its third Omicron wave in the coming weeks, as BA.4 and BA.5 become the dominant Covid strains. The new COVID-19 Omicron variants— BA.4 and BA.5 — are set to overtake the previously prevalent BA.2 variant in coming weeks, the NSW Health respiratory surveillance report said.

"It is anticipated that in coming weeks the BA.4 and BA.5 sub-lineages, first identified in early April, will become the dominant strains," a NSW Health spokesperson said.

"And will likely be associated with an increase in infections."

BA.4 and BA.5 are more infectious than previous Covid variants and subvariants, and are better able to evade immunity from vaccines and previous infections. So we’re likely to see a rise in case numbers.

How high are case numbers likely to rise?

Around Australia, we are starting to see a third wave of cases because of BA.4/5.

The effective reproduction number, or Reff tells us, on average, how many people an infected person will pass it on to, given the immunity in the population. All Australian states and territories now have a Reff greater than 1, meaning that even with the current levels of immunity, we are seeing an exponential growth in case numbers. This will inevitably lead to an increase in hospitalisation and deaths.

The second Omicron wave due to BA.2 was not as high as the first one caused by BA.1, probably because there were so many people infected with BA.1, that the ensuing immunity dampened the second wave down.

This third wave may not be as high as the second for the same reason.

New variant BA.4 and BA.5 NSW Sydney

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