BA.5 fuelling Covid wave globally, but the Omicron sub-variant is less than 10 percent in India
NEW DELHI: BA.5, the new fast-moving Omicron sub-variant, fuelling widespread Covid-19 wave globally, is not expanding or spiking hospitalisation rate in India so far.
According to the US Centers for Disease Control and Prevention (CDC), an estimated 65 percent of coronavirus variants in the US last week were of the fast-spreading BA.5 sub-lineage.
Good at evading past immune protection from vaccination or earlier infection, BA.4 and BA.5 were first identified in March, and the World Health Organisation (WHO) started tracking them in April. By May-June, this most transmissible sub-variant took over the world and caused spikes in countries like South Africa, the UK, Europe and Australia.
However, in India, the sub-variant along with BA.4 has not caused a spike or increase in hospitalisation rate, the way it dominates globally.
Speaking with this newspaper, Dr N K Arora, head of the Covid-19 Working Group of the National Technical Advisory Group on Immunisation (NTAGI), said in India, the BA.2 variant is still dominant.
“In India, BA.2 is still 85 percent. BA.4 and BA.5 are not expanding the way it is happening worldwide. The two Omicron sub-variants are less than 10 percent in the country,” he said.
In May, India reported its first BA.5 in Telangana when an 80-year-old man in Hyderabad tested positive for the sub-variant, as per the Indian SARS-COV-2 Genomics Consortium (INSACOG). The octogenarian was fully vaccinated.
What is worrying is that, like the Delta variant, which created havoc in India and other parts of the world, BA.5 also affects the lungs. Earlier, Omicron was described as mild with symptoms of cold or flu.
BA.5 is different, according to a study published in medRxiv, a Yale and British Medical Journal that publishes studies not yet certified by peer review. The study said that the sub-variant is shifting back to the lower respiratory tract - at least in animal models, “with a potential increase in disease severity and infection within lung tissue.”
The researchers referenced another May preprint study that found BA.5 and close relative BA.4 replicate more efficiently in the alveoli of human lungs than so-called stealth Omicron, BA.2.
“BA.5 not only gives the virus greater antibody evasion potential but concurrently has changed [where it tends to accumulate], along with an increased transmission potential in the community,” Australia’s Kirby Institute authors said.
As BA.5 can infect cells more like Delta than the previous Omicron family of variants, a top US scientist has referred to the new sub-variant as Deltacron - a Delta-Omicron hybrid.
According to Dr Eric Topol, a professor of molecular medicine at Scripps Research and founder and director of the Scripps Research Translational Institute, the term Deltacron is more appropriate for BA.5, even though the subvariant isn’t a true hybrid.
The technical lead on Covid-19, Maria Van Kerkhove, has also said that "BA.5 has a growth advantage over the other sublineages of Omicron that are circulating.”
However, she said there is no evidence that BA.5 is more dangerous than other Omicron variants. But stressed that spikes in cases could put health services under pressure and risk more people getting long Covid.