New virus Sub-variants(Omicron)
Context:
The Omicron sub-variants BA.2 and BA.2.38 are driving the current surge across the country. Cases of BA.4 and BA.5 are increasing. Scientists said that emerging strains have not led to any cluster formations till now.
Key points
- An average of 15,277 new COVID-19 cases were recorded for the last week.
- The surge has been driven by sub-variants of Omicron.
- The current surge in cases is because of the BA.2 sub-variant of Omicron, which also drove the 3rd wave in January, along with BA.1 and other sub-variant was branched off from it called BA.2.38.
- Delhi reported a couple of cases of the BA.5, sub-variant of Omicron.
- Researches believe that there is no clinical significance of this change.
BA.2.38
It is re-classified and it leads to milder disease, just like its parent sub-variant BA.2.
BA.2
This is the sub-variant that drove the winter surge in India, along with BA.1. BA.2 soon overtook its cousin BA.1, showing that it had a competitive advantage. Although the disease pattern was not different for the two, BA.2 seemed to be more transmissible.
BA.4 & BA.5
- These sub-variants were detected in South Africa in January and February.
- The variants triggered a surge of infections and became dominant.
- They are now spreading to Europe with BA.5 becoming the dominant variant in Portugal.
- 4 & BA.5 have a 13% to 15% transmission advantage over BA.2 and circumvent some of the immunity.
- These variants have 2 mutations: F486V, which lab studies have associated with the ability of the virus to evade some of the existing immunity; L452R which was found in the Delta Variant and associated with the ability to infect lungs.
Experience from other countries shows that the variants do not lead to an increase in severe disease, hospitalization and deaths.
This time doctors have hardly seen Covid-19 pneumonia inpatients, which had led to an increase in oxygen requirement and deaths during the Delta-variant-driven second wave of the summer of 2021.
BA.2.12.1
This sub-variant, which was first detected in New York, is thought to be 23%-27% more transmissible than the BA.2 sub-variant. It is also thought to evade some of the immunity gained through previous infection and vaccination.
CURRENT SURGE
- Genome sequences uploaded to the global database GISAID show that BA.2.38, branched off from BA.2 is dominant, accounting for 30% of sequences.
- This was followed by the BA.2 sub-variant, accounting for 28% of samples.
- Although BA.4 &BA.5 were detected almost at the same time, BA.5 was spreading faster, accounting for 7% of the sequences uploaded to the global database in the last 30 days.
- India has reported at least 120 sequences of BA.5 sub-variant, in Tamil Nadu and Karnataka.
- The other sub-variant that led the Covid-19 surge in South Africa, BA.4- 33 cases were identified, which account for less than 1%.
- 2.12.1 accounted for 5% of sequences.
- At least 190 sequences of this sub-variant were uploaded to the global database.
Changes between January wave & current wave
- The biggest difference, researchers from INSACOG, is that there is no cluster formation with any of the emerging sub-variants.
- When Omicron was on peaks, there was clear cluster formation, which helped researchers quickly connect the dots that the increase was driven by the new variant.
Anticipation:
- Scientists from INSACOG say that the emerging sub-variants are not creating cluster formations as the sub-variants during the January wave had done.
- These cases were observed not forming clusters.
- No changes in symptoms and hospitalizations are observed.
- The scientists will hold further discussions with the National Center for Disease Control(NCDC) to try and correlate the findings of genome sequencing with the epidemiological data on the ground.
- Although BA.2.38 was recently reclassified and is now present in many samples, no epidemiological evidence to suggest any change in the disease pattern.
