Kolkata: Nearly 80% of the positive covid samples sent for the genome sequencing by the laboratory in the city have been found containing sub-genealogy of BA.2 from the omicron variant, nicknamed the ‘version of the stealth’, because it cannot be taken in the RT-PCR test and requires sequencing genomes.
Interestingly, almost nothing found infected with BA.2 has a direct history of foreign trips; Other sub-lineage – BA.1 – has been detected in those who have traveled abroad in the past, said a senior health official.
From the original B.1.1.529 variant (first detected in South Africa), Omicron has now divided into three sub-types: BA.1, BA.2 and BA.3.
There is no example of BA.3 so far identified in India.
In Maharashtra and several other countries, BA.1 dominantly circulated in the community, quickly replacing the Delta variant, as reported on TOI Monday.
BA.2 cannot be identified by the primer used in the RT-PCR test.
Sub-genealogy BA.1 Brings the S-Gen school dropout mutation, which is ba.2 no.
The absence of a s-gen mutation in the RT-PCR test, therefore, shows an omicron indication.
However, to identify ba.2 infections, sequencing genomes are a must.
About 150 positive samples from the community have been sorted.
Even though around 80% are omicron-positive, all found ba.2-positive, except for one or two samples.
All of these samples have a CT value below 30, showing high viral load.
This sample was sent for genome sequencing between 22 and December 28.
‘BA2 reasons for cluster infections’ findings show that the sub-lineage of BA.2 is dominantly circulating in the community in Kolkata and a side by side, where most of the samples have been sent for genome sequencing.
“It is possible that BA.2 causes a local cluster infection.
Even because this sub-genealogy is different from his other siblings, it genetically belongs to the same family and therefore there is no significant difference in the clinical course of the disease,” Immunologist said in ganguly Indian Chemical Biology Institute.
In the sample sent by one laboratory, 34 positive covid samples found with BA.2.
One sample is Omicron BA.1 and eight are Delta and Delta Plus.
Of the 17 positive covid samples sent by other labs, 14 were Omicron and included in the lineage ba.2 and the remaining delta.
The findings in 50 samples sent by the third lab showed that 35 was BA.2.
“Viruses will continue to mutate.
Therefore the need to supervise the sequence of genome,” said Microbiology of the Peerless Bhaskar Narayan Chaudhuri Hospital.
The government, around the third week of December, has decided to send all positive samples with CT values ​​under 30 for sequencing genomes to detect the transmission of the Omicron community.
Thus, laboratories in Kolkata, Salt Lake and New Town began sending samples.
The Ministry of Health has reversed decisions a week later when it was clear that the transmission of the Omicron community began.
“About 70% of our samples were tested positive for Omicron, most of the Lineage BA.2.
This was a week ago.
Given the high transmission, the presence of omicron is likely to increase more,” said Shelly Sharma Ganguly, Amri microbiologist Dhakuria.
The health department has asked for Labs to send only samples that have a foreign travel history.
“Omicron replaces Delta.
Although there are indications about subtypes of BA.2 which is more common, we need a greater sample size to draw conclusions,” said RN Tagore International Institute of Cardiac Sciences Microbiologist Swatilekha Banerjee.