Dr George Christos

covid19 & other Infectious diseases

BA.2 is not Omicron. And what are BA.4 and BA.5?

BA.2 is very different to BA.1 and BA.3. Why is it called Omicron? Because it came from South Africa around the same time. I thought the whole purpose of using Greek letters was so we could not tell where the variant came from. Delta always reminds me of the Ganges delta plains and hence of India. 😀

In the gene for the spike protein on the surface of the virus, BA.2 has eight mutations not found in BA.1.

Does anyone have any information on BA.4 and BA.5? I do not see them in the GISAID database yet, although GISAID tells me that 112 cases of BA.4 have been recorded so far and 151 of BA.5. Their genetic mutations are not listed as yet. Do they look more like BA.1 and BA.3, or BA.2? I added some info I found about them at the end of this blog.



By the way there are 54 subvariants of Omicron (B.1.1.59) so far and they are exploding in number. With a worldwide “virus pool” of about 100 million people we can expect a proliferation of new variants, subvariants and recombinant variants like Deltacron and XE Omicron. These “virus pools” were generated by “vaccine complacency” and now will be a regular part of life.

Emergence of Omicron third lineage BA.3 and its importance - Desingu - 2022  - Journal of Medical Virology - Wiley Online Library
Eric Topol on Twitter: "New @UKHSA report on variants XE, a hybrid of BA1  and BA.2, has a growth rate 12.6% above that of BA.2.  https://t.co/FmD1GCbZwR what, if any, functional/clinical significance is
Mutations in BA.4, BA.5 sub-variants: Cases detected in South Africa,  Denmark, Botswana, Scotland and UK | Special-reports – Gulf News
Tulio de Oliveira on Twitter: "New Omicron BA.4 & BA.5 detected in South  Africa, Botswana, Belgium, Germany, Denmark, and U.K. Early indications  that these new sublineages are increasing as a share of


prevalence of omicron variants in South Africa 11/4/2022

This tweet has lots more information about BA.4 and BA.5. Although BA.1 has drifted into a flu-like virus, the same cannot be said about BA.2 quite yet. As I have noted the BA.2 variant in Hong Kong (namely BA.2.2) had a CFR of around 2%. Also BA.2.9 increased the CFR from 0.05% (fro BA.1) to 0.5%.


Okay, the penny just dropped. BA4 and BA.5 have mutated from from BA.2 with the bad mutation L452R mutation, found in the Delta variant, which made it more severe and infectious. See a blog I did a few days ago.

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