COVID-19 Notes
By Dr. Satish K Gupta*
Omicron BA.2 is inherently 30% more transmissible than BA.1
Omicron’s New Sibling BA.2 – Cunning but kind?
The Omicron now accounts for nearly all of the COVID-19 infections globally. However, a close relative, known as BA.2, has started to outcompete Omicron in parts of Europe and Asia, especially India.
Globally, Omicron BA.1 accounted for 98.8% of sequenced cases submitted to the public virus tracking database GISAID as of Jan. 25. But several countries are reporting recent increases in the subvariant known as BA.2.
Is BA.2 more Severe?
WHO: Omicron subvariant BA.2 likely to have the same severity as ‘original’ omicron. The BA.2 form of the Omicron COVID-19 variant doesn’t seem to be any more severe than the original BA.1 form, a World Health Organization (WHO). Countries like India and Denmark where BA.2 is now overtaking, are not seeing any higher bumps in hospitalization than expected.
Will vaccines work on BA.2?
Vaccines also continue to provide similar protection against the different forms of Omicron – WHO
Which countries is BA.2 already-dominant version?
The subvariant is already becoming dominant in the Philippines, Nepal, Qatar, India and Denmark. It’s thought to be in at least 57 countries. BA.2 is going to be everywhere in the world, that it’s going to sweep and will be the dominant variant soon in most countries.
Where was it first detected?
The earliest documented case dates back to 17 November in South Africa.
How is it different from original Omicron BA.1?
BA.2 differs by about 40 mutations from the original Omicron lineage. BA.2 has mutations that make it smarter than the original Omicron BA.1 at dodging vaccine-induced immunity.
Scientists are also probing the variant’s ability to dodge vaccine-induced antibodies in lab dish studies. Glaxo SmithKline is testing its monoclonal antibody, sotrovimab, against BA.2
Why BA.2 called the stealth version?
While it had been easy to identify BA.1 due to a missing S target gene used in common PCR tests, but that is not the case with BA.2.
The BA.2 is being called the ‘stealth’ variant of the Omicron because it does not have the same missing S target gene. it can be monitored by Genome sequencing only. To be more precise one N-Terminal Domain gene difference—a deletion at amino acids 69 and 70 that is present in BA.1 and not in BA.2
Can it all together be a new Variant of Concern?
Some scientists even think BA.2 shouldn’t be considered Omicron sub-variant. In the near future, BA.2 may get its own variant of concern badge.
Can people infected with BA.1 get reinfected with BA.2?
Yes, but not all. Some cases of reinfection have been reported from Denmark.
How much smarter is BA.2 than its sibling BA.1?
1. BA.2 is inherently 30% more transmissible than BA.1.
2. On lines of Omicron which was already known to evade antibodies, studies in Danmark found that BA.2 maybe even better at dodging vaccine-induced immunity: Vaccinated and boosted people were three times as susceptible to being infected with BA.2 as with BA.1. Vaccinated but unboosted people were about 2.5 times as susceptible, and unvaccinated people 2.2 times as susceptible.
What the emergence of BA.2 means for the Omicron surge and the pandemic overall?
Despite higher transmissibility of BA.2 there has been continuous, steep decline in the number of intensive care unit patients and a decrease in the number of hospital admissions related to SARS-CoV-2. *Despite more than 65% case of BA.2, the Danish government was so confident the variant won’t cause major upheaval that it lifted almost all pandemic restrictions on February 1, 2022.
Will there be more sub-variants?
In addition to BA.1 and BA.2, the WHO has listed two other subvariants under the Omicron umbrella: BA.1.1.529 and BA.3. All are closely related genetically, but each features a mutation that could alter how they behave.
What is the scenario in India?
BA.2 is rapidly replacing Delta and Omcron BA.1. So BA.2 is now a major variant to drive the pandemic but hospitalisations and ICU admission remain low, mortality is not a serious concern.
So what do we learn from this evolution pattern?
Sars Cov 2 is evolving to more and more transmissible variants that don’t not cause serious disease despite its immune invasion capabilities. So far these can be taken as signs of ending pandemic.
Also read:
- India sees 40% weekly rise in deaths; WHO to prioritise study of new Omicron lineage BA.2
- Can vaccinating 70% of world population set in herd immunity?
*Dr. Satish K Gupta is an MD in Medicines, a Visiting Senior Consultant Physician and Internist at Max Super Speciality Hospital, and a Clinical Assistant Professor at GS Medical College, Chaudhary Charan Singh University, Meerut. He is the author of Journey of COVID in India: A Doctor’s Perspective.
