A new omicron subvariant of the virus that causes COVID-19, BA.2, is fast becoming the predominant source of infection as cases rise around the world. University of South Carolina immunologists Prakash Nagarkatti and Mitzi Nagarkatti explain what makes them different from previous variants, whether there will be another surge in the US, and how best to protect yourself.
What is BA.2 and how does it relate 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 quickly became the dominant strain in many countries including India, Denmark and South Africa. It continues 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 recorded omicron subvariant, BA.1, was first reported in November 2021 in South Africa. While scientists believe all subvariants may have appeared around the same time, BA.1 was primarily responsible for the winter spike in infections in the northern hemisphere in 2021.
The first Omicron subvariant, BA.1, is unique in the number of changes it has compared to the original version of the virus – it has over 30 mutations in the spike protein, which helps it enter cells. Spike protein mutations are of great concern to scientists and public health officials because they affect how infectious a particular variant is and whether it can escape the protective antibodies the body produces after a vaccination or previous COVID-19 infection.
BA.2 has eight unique mutations not found in BA.1 and is missing 13 mutations that BA.1 has. However, BA.2 shares about 30 mutations with BA.1. Because of its relative genetic similarity, it is considered a subvariant of Omicron, as opposed to an entirely new variant.
Why is it called the “Stealth” variant?
Some scientists have dubbed BA.2 the “Stealth” variant because, unlike the BA.1 variant, it lacks a specific genetic signature that distinguishes it from the Delta variant.
While standard PCR tests are still able to detect the BA.2 variant, they may not be able to distinguish it from the delta variant.
Is it more contagious and deadly than other variants?
BA.2 is considered more transmissible but no more virulent than BA.1. This means that while BA.2 can spread faster than BA.1, it may not make people sicker.
It is worth noting that while BA.1 dominates case numbers worldwide, it causes less severe disease compared to the Delta variant. Recent studies from the UK and Denmark suggest that BA.2 may carry a similar hospital risk as BA.1.
Does previous infection with BA.1 protect against BA.2?
Yes! A recent study suggests that people previously infected with the original BA.1 subvariant have robust protection against BA.2.
Because BA.1 has caused widespread infections around the world, it is likely that a significant percentage of the population has protective immunity to BA.2. Because of this, some scientists predict that BA.2 is less likely to cause another big wave
While the natural immunity gained after COVID-19 infection can provide strong protection against reinfection by earlier variants, it weakens against Omicron.
How effective are vaccines against BA.2?
A recent preliminary study of over 1 million people in Qatar, which has not yet been peer-reviewed, suggests that two doses of either Pfizer’s BioNTech or Moderna’s COVID-19 vaccine several months prior to symptomatic infection by BA .1 and BA.2 protect decrease to around 10%. However, a booster shot could bring the protection back close to the original level.
Importantly, both vaccines prevented hospitalization or death by 70% to 80%, and this efficacy increased to over 90% after a booster dose.
How concerned does the US need to be about BA.2?
The rise of BA.2 in certain parts of the world is most likely due to a combination of its higher transmissibility, waning people’s immunity and the easing of COVID-19 restrictions.
CDC data suggests BA.2 cases are steadily increasing, accounting for 23% of all cases in the US as of early March. Scientists are still debating whether BA.2 will cause another surge in the US
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Although there may be an increase in BA.2 infections in the coming months, protective immunity from vaccination or previous infection protects against serious disease. This may reduce the likelihood that BA.2 will cause a significant increase in hospital admissions and deaths. However, the US lags behind other countries when it comes to immunizations and falls even further behind when it comes to booster shots.
Whether there will be another devastating rise depends on how many people are vaccinated or have previously contracted BA.1. However, it is safer to generate immunity through a vaccine than through infection. Getting vaccinated and boosted, and taking precautions like wearing an N95 mask and social distancing are the best ways to protect yourself from BA.2 and other variants.
By Prakash Nagarkatti, Professor of Pathology, Microbiology and Immunology, University of South Carolina and Mitzi Nagarkatti, Professor of Pathology, Microbiology and Immunology, University of South Carolina
This article was republished by The Conversation under a Creative Commons license. Read the original article.
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