Omicron subvariants BA.1 to BA.5 - What we know about them

The Omicron variant has become the dominant strain of Covid-19 not just in India but across the globe. While the current waves of the pandemic are much less severe compared to the ones caused by the dreaded Delta variant, experts have asserted the need to keep a watchful eye.

Last week, India detected its first cases of Omicron BA.4 and BA.5 variants, with Maharashtra confirming first cases on Saturday. The two subvariants are behind the fifth wave of the pandemic in South Africa and are also being reported to be the cause of recent surge of cases in the US and several European and Asian countries.

Subvariants of Omicron have been rapidly emerging since the beginning of the year. The original Omicron strain BA.1 was replaced by BA.2, also called ‘stealth Omicron’, by late January. Since then, more subvariants have emerged in BA.3, BA.4, BA.5 and the XE variant which contained mutations of both BA.1 and BA.2.

Omicron strain of Covid-19 and its subvariants – risk and symptoms

The Omicron variant emerged around the turn of the year and was responsible for the surge in cases during India’s third wave earlier this year. It gradually overtook Delta variant as the dominant strain around the world. While more contagious, it generally results in less severe infections compared to Delta. But being able to spread faster and among more people, the Omicron variant has produced several subvariants owing to the bigger opportunity to mutate. Some studies suggest that some Omicron sub lineages may carry the ability to escape both natural and vaccine generated immunity.

The newer subvariants of Omicron - BA.4 and BA.5 - have not appeared to have increased severity of symptoms in comparison to the earlier subvariants. Being subvariants of the same strain, they have similar symptoms.

The symptoms shown by the latest Omicron subvariants of BA.4 and BA.5 fall in line with the ones from the earlier subvariants. These include cough, temperature, fatigue, gastrointestinal symptoms, headache, runny nose, skin rash with smell or taste loss also seen in some cases.

Research evidence claims that the newer variants may be able to reinfect people infected with previous variants of Omicron earlier. Possible infections in vaccinated people also cannot be ruled out. While there is no evidence of them being more severe, BA.4 and BA.5 are feared to be around 12% to 13% more contagious than the BA.2 subvariant.

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