What is Omicron sub-variant BA.2?
BA.2, also coined as the "stealth" variant, is a relative of Omicron's original variant, BA.1, which tore through the Australian community over Christmas and the New Year period.
But in the months since, it appears that BA.2 has emerged as the dominant strain in New South Wales, per a study by UNSW.
According to its data, BA.1 and BA.2 have differing genetic sequences, including in its proteins and amino acids.
So how different is BA.2 to the original Omicron?
Unfortunately, it looks like BA.2 is more transmissible than Omicron BA.1, and the reason we know this is because it has become the dominant strain across several countries.
In order for a variant to do this, it must be able to evade the immune response which has already been strengthened by BA.1 and other COVID-19 variants—as well as vaccination effecacy.
UNSW School of Population associate professor James Wood said BA.2 has been more dominant than BA.1 for about a month in New South Wales, and within the next month, it will be accountable for more than 90 per cent of cases in the state.
What are the symptoms of Omicron BA.2? Is it more severe than the original variant?
When Omicron BA.1 first emerged into the community, it was widely reported as being milder than previous COVID strains including Delta. Luckily, early indications suggest BA.2 is no more severe than BA.1—the only major difference is that it's far more infectious.
Australian Medical Association NSW president Danielle McMullen said this was "reassuring".
"So far, we don’t have any data from the rest of the world that it is any more or less severe, which is reassuring,” she told Today on March 11.
"We know that Omicron has been a milder variant than previous ones before so we’re hopeful that continues. It’s just that we are expecting to see these higher case numbers again, which of course causes disruption to the community and even a milder variant doesn’t leave you feeling very well."
Can you catch Omicron BA.2 if you've already had Omicron BA.1?
Being infected by Omicron BA.2 if you've already had BA.1 is possible, but rare, per data from a Danish study published in February.
Out of the 187 reinfection cases of COVID it studied, 47 cases were BA.2 reinfections shortly after a BA.1 infection. But of this, 89 per cent of the 47 cases were unvaccinated.
But Dr Egon Ozer, an infectious disease expert at Northwestern University Feinberg School of Medicine in Chicago, told The Guardian that it was too early to tell the full extent of how reinfection might occur in BA.2 following BA.1.
"This could be sort of a two-humped camel kind of wave. It’s too early to know if that will happen."
But that said, what we know for sure is that vaccines (and particularly the booster shot) is our best line of defence when it comes to protecting ourselves against all COVID variants.
