Omicron Sub-Variant ‘BA.2’ 1.5 Times More Transmissible Than The Original Strain: Danish researchers

The Omicron subvariant BA.2, dubbed "Stealth Omicron", is rising around the world with at least 55 countries, including India.

A research team led by Danish researchers has claimed that the BA.2 sub-variant of Omicron is 1.5 times more transmissible than the original Omicron strain, which is also referred to as B.1.1.529. The World Health Organization (WHO) has identified three main substrains of Omicron: BA.1, BA.2, and BA.3.

Researchers at Denmark's Statens Serum Institut (SSI) found that BA.2 appeared to be 1.5 times more contagious than BA.1 This indicate that the wave of infections will be higher than it was earlier expected and will extend further into February, warned Tyra Grove Krause, an infection epidemiology expert at SSI.

Also known as "Stealth Omicron", the subvariant BA.2 is spreading around the world. At least 55 countries, including India, have reported cases of the subvariant, as per the global variant tracking database. The presence of BA.2 have been confirmed in almost half of US states with at least 127 known cases reported nationwide as of Friday, as shown in the database.

However, the CDC, in a statement Friday, said that BA.2 is currently circulating at a low level in the US.

Stealth Omicron becomes Denmark's dominant Covid type

The SSI noted that, as of January 26, BA.1 remained the most common Omicron sub-variant worldwide, accounting for 98 per cent of cases at that time. But in Denmark, the BA.2 sub-variant has already become the dominant Covid type.

However, it is yet to be known whether BA.2 is more severe than BA.1. But what is known is that they have many differences in their mutations.

Speaking to a news channel, Troels Lillebaek, the chairman of Denmark's committee that conducts surveillance of Covid variants, said that the BA.2 variant contains five unique mutations on a key part of the spike protein, known as the receptor binding domain. Mutations on this part are often associated with higher transmissibility.

According to the UK Health Security Agency, stealth Omicron has a "substantial" growth advantage over the original omicron.

However, the BA.2 sub-variant of Omicron doesn't appear to reduce the effectiveness of existing vaccines any more than the original Omicron strain, a preliminary assessment has suggested.