Another Variant BA.2 - do NOT panic!
Zaurez Khan M.D.
Another variant already? I mean we just heard of omicron few weeks back (10 weeks to be exact) and here we are! BA.2.
Where was it found first?
November 2021- South Africa
Early December 2021– positive samples from Philippines, Denmark, India, UK and now spreading across the globe.
As of last week, it is found in 57 countries (Source:WHO)
How is it different?
Omicron has 3 sub variants – 1.1.529.1 (original), 529.2 (BA.2) and 529.3
Common mutations with omicron (BA.1): 32
Unique mutations in BA.2: 28
Some perspective: Delta had 9 mutations in S protein and omicron had over 30, this BA.2 has even more mutations. That does not necessarily make it more dangerous.
However with that number of mutations it might as well get a new name!
Sibling rivalry?
Well this new sibling is outcompeting the original omicron or BA.1 in terms of high transmission. We certainly do not wish to see any further achievements.
Can it be detected by antigen tests?
Yes, but less sensitivity is being reported. As in my previous post, if symptomatic and antigen test is negative follow by a PCR test.
Can it be detected by PCR?
Yes. But it has more mutations it can make it difficult to detect by certain PCR tests that have single gene target. PCR tests with multiple gene targets will not be affected. You can find the approved tests at fda.gov.
Omicron 529.1 has SGTF (S gene target failure)
Omicron 529.2 (BA.2) does NOT have SGTF. That is why it is also called the “stealth variant.”
What is S gene target failure?
S gene is one of the target genes used by PCR tests to detect Covid-19. The S gene target is not identified in the original omicron, so it’s called S gene drop out or S gene target failure. That is because of the S69-70 gene deletion, which is not present in the new BA.2 variant.
For proper identification of this variant (or any variant)– genomic sequencing needs to be done.
More transmissible?
Yes. There is a preprint Danish study showing higher transmission (posted January 30,2022, link: https://www.medrxiv.org/content/10.1101/2022.01.28.22270044v1). There is a possibility that it can replace the original omicron (BA.1) globally. In fact, it has already become the predominant strain in Denmark.
Can we get omicron if we had delta infection?
Yes. There is an Imperial College London study that shows that risk of infection is 5.4 times more likely with omicron than with delta.
Can we get omicron twice?
Yes, there is a strong possibility. Why am I using the word possibility?... because we don’t have published data yet. There have been reports of people getting re-infected after omicron, which may very well be this variant??
Is it more dangerous?
No published data yet. South Africa and Denmark cases so far do NOT show more severe disease than delta. Scientists are not expecting it to be worse than omicron (which is less severe than delta) but it’s too early to say for sure.
Immune escape? Or will vaccines be effective?
Yes. There is however one mutation linked to immune escape that was in the original omicron is missing - G446S. This is making scientists think that it may have less immune escape compared to BA.1, but not necessary. You can check an immune escape calculator developed by jbloomlab here: https://jbloomlab.github.io/SARS2_RBD_Ab_escape_maps/escape-calc/
Vaccines are still effective. The efficacy may be lower, but as I mentioned in my previous post, there is clear evidence that vaccines reduce risk of severe disease (graphs in my previous post). Vaccines also reduce transmission and emergence of newer strains. Having said that, if this continues we will need more strain specific vaccines. And yes..masks are still very important. Even if the virus is not as severe, you never know how your body will react to it.
What you need to know is that it is somewhat similar to the original omicron, vaccines are still helping and there is no need to panic.
Article by,
Dr. Zaurez Khan
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