A new omicron subvariant of the virus that causes COVID-19, BA.2, is quickly becoming the predominant source of infections amid rising cases around the world. Immunologists Prakash Nagarkatti and Mitzi Nagarkatti of the University of South Carolina explain what makes it different from previous variants, whether there will be another surge in the U.S. and how best to protect yourself.
What is BA.2, and how is it related to omicron?
BA.2 is the latest subvariant of omicron, the dominant strain of the SARS-CoV-2 virus that causes COVID-19. While the origin of BA.2 is still unclear, it has quickly become the dominant strain in many countries, including India, Denmark and South Africa. It is continuing to spread in Europe, Asia and many parts of the world.
The omicron variant, officially known as B.1.1.529, of SARS-CoV-2 has three main subvariants in its lineage: BA.1, BA.2 and BA.3. The earliest omicron subvariant to be detected, BA.1, was first reported in November 2021 in South Africa. While scientists believe that all the subvariants may have emerged around the same time, BA.1 was predominantly responsible for the winter surge of infections in the Northern Hemisphere in 2021.
The first omicron subvariant, BA.1, is unique in the number of alterations it has compared to the original version of the virus – it has over 30 mutations in the spike protein that helps it enter cells. Spike protein mutations are of high concern to scientists and public health officials because they affect how infectious a particular variant is and whether it is able to escape the protective antibodies that the body produces after vaccination or a prior COVID-19 infection.
BA.2 has eight unique mutations not found in BA.1, and lacks 13 mutations that BA.1 does have. BA.2 does, however, share around 30 mutations with BA.1. Because of its relative genetic similarity, it is considered a subvariant of omicron as opposed to a completely new variant.
Why is it called a ‘stealth’ variant?
Some scientists have called BA.2 a “stealth” variant because, unlike the BA.1 variant, it lacks a particular genetic signature that distinguishes it from the delta variant.
While standard PCR tests are still able to detect the BA.2 variant, they might not be able to tell it apart from the delta variant.
Is it more infectious and lethal than other variants?
BA.2 is considered to be more transmissible but not more virulant than BA.1. This means that while BA.2 can spread faster than BA.1, it might not make people sicker.
It is worth noting that while BA.1 has dominated case numbers around the world, it causes less severe disease compared to the delta variant. Recent studies from the U.K. and Denmark suggest that BA.2 may pose a similar risk of hospitalization as BA.1.
Does previous infection with BA.1 provide protection against BA.2?
Yes! A recent study suggested that people previously infected with the original BA.1 subvariant have robust protection against BA.2….
