A BA.4.6 subvariant of Omicron, which is rapidly spreading in the USA, is now also spreading in the UK, reported the electronic edition “Science Alert” (link is external), cited by BTA.
In the UK’s Health Safety Agency’s latest Covid briefing, it says that in the week starting August 14, 3.3 percent of samples had the BA.4.6 sub-variant. Since then, its proportion has risen to 9 percent of sequenced cases.
According to the US Centers for Disease Control and Prevention, 9 percent of new cases in the US recently have the BA.4.6 subvariant.
It has also been identified in several other countries.
What is known about it is that it is the successor to Omicron’s BA.4 variant, first discovered in South Africa in January 2022. Since then, it has spread around the world along with the BA.5. It is not yet clear how BA.4.6 arose, but it may be recombinant – obtained when two different variants of the SARS-CoV-2 virus that causes COVID-19 to infect a person at the same time.
Although BA.4.6 is similar to BA.4 in many ways, it has a mutation in the spike protein. This R346T mutation has also been found in other variants and is associated with immune evasion – helping the virus to bypass antibodies acquired from a vaccine or illness.
Fortunately, Omicron causes less overall morbidity and fewer deaths than other options. This is expected to be the case for the BA.4.6 sub-variant as well. So far, this subvariant has not been reported to cause more severe symptoms.
However, sub-variants of Omicron are known to be more easily transmitted than previous variants. BA.4.6 appears to be even better at evading the immune system than BA.5, which is still dominant.
BA.4.6’s ability seems even better at evading the immune system. It may be limited to some extent by the new bivalent boosters specifically targeting Omicron as well as the original strain of SARS-CoV-2.
The emergence of BA.4.6 and other new variants is troubling because it shows that the virus is still around and mutating to find new ways to overcome the immune response due to vaccines and previous illnesses.