Omicron BA.2 Explained

With the Omicron BA.2 sub-variant of the COVID-19 virus now becoming the dominant strain of new cases in Australia and elsewhere, understandably, there have been many questions around what this means for COVID care.

We have asked Western Victoria PHN clinical advisor and Wimmera GP, Dr Kate Graham, to answer common questions on Omicron BA.2.

When was Omicron BA.2 variant first identified?

When Omicron was first detected late in 2021, there were already 3 distinct lineages BA.1, BA.2 and BA.3 Initially BA.1 was dominant. However, the proportion of BA.2 is now increasing

How is it different to the original Omicron variant?

BA.2 has at least eight different mutations on the spike gene compared to BA.1. Omicron BA.2 was initially referred to as theĀ  ‘stealth’ variant it does not have the same S-gene deletion that allowed BA.1 to be easily distinguished from other variants on PCR tests.

How is it more contagious than previous variants?

The mutations appear to make it more transmissible rather than changing how it evades detection. It is 1.4 times more infectious than BA.1 and 4.2 times more infectious than the Delta variant.

Are any symptoms of Omicron BA.2 different to previous variants?

The clinical picture is the same for BA.1 and BA.2

Are any specific populations more susceptible to getting Omicron BA.2?

The population and medical risk factors for severe disease are the same for all variants.

If someone has previously had COVID-19, are they immune from the new variant?

The immunity from previous infection to the Delta variant decreases rapidly when faced with an Omicron infection. While infection with Omicron BA.1 gives good immunity against BA.2, this immunity will decrease over time and there are cases of re-infection with BA.2 after an initial BA.1 infection.

How does getting vaccinated help with immunity to Omicron BA.2?

COVID-19 vaccines are effective against BA.1 and BA.2. However, at least three doses in adults are needed to optimise immunity and minimise the chance of acquiring a severe case of COVID.

Is the management of care for Omicron BA.2 the same as for the previous variant?

There is no difference to the public health advice and at-home care advice. Oral anti-viral therapies are equivalent. However, there may be some differences in responses to monoclonal antibody therapies.


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