How dangerous are the BA.2 and BA.3 sub-variants compared to the Omicron BA.1 that we already know?
South Africa has one of the most robust public health systems in the world, carefully monitoring their SARS-CoV-2 case load, which has been dominated these last few months by the Delta variant. In recent months, however, South Africa’s case load has increased sharply due to the variant: B.1.1.529, sub-lineage BA.1.(1) First detected in a specimen collected on November 9th 2021, the new variant was reported to the World Health Organization (WHO) on the 24th and deemed a “variant of concern.”(3)
This variant has nearly twice as many mutations as the Delta variant, many of which are associated with transmissibility and immune evasion.(2)The increased transmissibility of Omicron, the ability of the virus to spread between people, when compared to the already-highly-transmissible Delta variant, is of great international concern.
Now a new sub-variant of Omicron B.1.1.529 is making the news: Called BA.2. The BA.2 strain is a prevalent form of Omicron in Denmark, making up about half of the cases there. It has been found in 40 countries and is prevalent in India, Sweden, and Singapore. It is now the most prevalent variant in South Africa. In the US, it is estimated that BA.2 makes up about 5% of all Covid cases. It is believed that that the BA.2 sub-variant is no more lethal that the original BA.1 variant, although research is ongoing. Hospitalization rates so far have been reported to be the same as the original Omicron BA.1 sub-variant. However, this new omicron coronavirus sub-variant appears to be slightly more contagious. Data out of Denmark suggests that BA.2 is about 1.5 times more contagious than the original BA.1 strain of omicron.(6) BA.2 has been nicknamed the “Stealth Variant” because it is more difficult for the PCR test to identify the variant, although it can identify the virus itself without difficulty. (5)
BA.3 is another sub-lineage of Omicron that shows mutations in the in spike protein. However, they are not unique mutations, and show a combination of mutations found in the BA.1 and BA.2 spike proteins.(8)
Meanwhile, sewage wastewater continues to be monitored for the virus overall. The wastewater district in South Boston reports on January 29th that an average of 1,328 copies of viral RNA per milliliter of water were found, which is about an 88% plummet from the Omicron peak in early January.(6)
Preventive steps remain our first and best methods of reducing the spread of SARS-CoV-2; physical distancing and avoiding crowded spaces, masking, and maintenance of an up-to-date vaccination status. Please consult your local public health professionals for further advice and recommendations to protect yourself, your family, and your community. Also, it is encouraging that early treatment protocols have been found to be of value in preventing hospitalizations.(7)