 "No evidence to suggest AY.4 has higher infectivity rate than Delta: Expert")
There is no evidence to suggest that AY.4, a sub-lineage of the Delta variant of the coronavirus, has a higher infectivity rate than Delta, and it is not a new variant, Rakesh Mishra, former director of the Centre for Cellular and Molecular Biology (CCMB), said on Monday.
Six persons in Indore district of Madhya Pradesh were found infected with AY.4, Chief medical and Health Officer (CMHO) of the state B S Saitya said.
He said all the six, who were found to be infected with the AY.4 variant, were fully vaccinated. They have recovered after treatment, he added.
"There is no evidence or observation to suggest that there are more vaccine breakthrough or reinfections or more infectivity due to AY.4. At the moment, it does not look like it," Mishra told PTI.
AY.4 is a sub-lineage of the Delta variant of the coronavirus, which was driving the deadly second wave of the infection that killed thousands from March to May.
"AY.4 is not a new variant," Mishra, who headed the Hyderabad-based CCMB that is at the forefront of genome sequencing of the coronavirus, said.
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He is now the director of the Tata institute for Genetics and Society in Bengaluru.
Mishra, however, stressed that observing Covid-appropriate behaviour is still very important as COVID-19 is yet to reach the pandemic stage.
Recent relative expansion of the AY.4 lineage, compared to B.1.617.2, in INSACOG data should be seen in the light of global evidence regarding no substantial difference between the Delta lineages so far, INSACOG, a genome-sequencing consortium, said in its October 4 bulletin.
However, the matter continues to be monitored and correlated clinically, it added.
Globally, the AY.4 lineage is most frequently seen, with the highest levels in the UK. In the ongoing outbreaks across the US, AY.4 has not outcompeted the other Delta lineages, the October 4 bulletin said.
Of the 39,283 samples of the Variant of Concern (VoC) and Variant of Interest (VoI) sequenced, 4,143 were of the AY series, it said.
Global evidence does not suggest any Delta lineage being substantially different from the others and as of now, the micro-lineage analysis is only for epidemiological surveillance, the INSACOG bulletin said.
The September 20 bulletin of INSACOG said the clinical characteristics of AY.4 infections are very similar to B.1.617.2 infections in initial studies from Maharashtra.
"There is presently no additional clinical or public health concern regarding these sub-lineages," it said.
INSACOG's September 13 bulletin said Delta and the Delta sub-lineages continue to be the main VoC in India.
"AY.4 is the most frequently seen sub-lineage in recent sequences from India as well as globally," it added.