Study finds sub-lineage behind rise in COVID-19 cases in Europe, US
The BA.5 sub-lineage of the Omicron variant of the novel coronavirus is four times more resistant to antibodies than BA.2, according to recent research.
The sub-lineage is also behind the surge in COVID-19 infections across Europe and the United States, the study published in Nature journal has found
South Africa reported the first Omicron case in November 2021. Since then, its sub-lineages have continued to fuel one spike after another across the world.
The study is based on a systematic antigenic analysis of surging Omicron sub-variants.
It underlined concerns about the additional mutations in the spike proteins of the virus. As a result, the infection is able to evade “neutralising antibodies, thereby further compromising the efficacy of COVID-19 vaccines and therapeutic monoclonals.”
Repeatedly touted as the “worst variant” of the SARS-CoV-2 virus, the emergence of BA.5 is the latest addition to the Omicron family tree, which seems to be expanding rapidly.
While the sub-variants have not been allotted a Greek name yet, but the World Health Organization (WHO) has classified them under a novel group — Omicron sub-variants under monitoring.
Alongside BA.4, these sub-variants have more in common with BA.2 than BA.1.
Their unique mutations allow them to enter the human cells more easily and evade immunity even better than their predecessors.
It remains unclear whether BA.5 is more virulent.
South Africa and Portugal are two countries which have already undergone a BA.5 wave. However, the sub-variant triggered a distinct surge in both countries.
BA.5 was behind South Africa’s fifth wave. The wave of COVID-19 cases peaked well before the halfway mark for its preceding wave caused by BA.2.
The waves of COVID-19 cases in South Africa. Chart: Our World in Data
There was an almost negligible growth in the number of deaths corresponding to the same period as the BA.5 wave.
On the other hand, Portugal saw a rise in deaths and hospitalisations as BA.5 ripped through the country.
Its sixth wave accounted for 19 per cent of all its infections and 6 per cent of deaths since the pandemic began, Down To Earth (DTE) had reported earlier.
With one of the highest vaccination coverage in the world — at least 87 per cent of the population is fully vaccinated and over 65 per cent have received boosters — Portugal was the best-case scenario.
However, BA. 5’s immunity evading characteristics has made it the fittest variant till now, so relying on vaccination alone will not be enough.
This example illustrates how BA.5 will likely manifest itself in varying ways depending on the country.
The waves of COVID-19 cases in Portugal. Chart: Our World in Data
More than two years into the pandemic, each nation has a distinct immunity profile — this depends on several factors, including vaccine coverage, which vaccine has been used and what variant has dominated in the past.
“It might be 5 per cent in some countries and 30 per cent in others. It all depends on their immunity profile,” Christian Althaus, a computational epidemiologist at the University of Bern, Switzerland, told Nature on the size of BA.4 and BA.5 waves.
The extent of vaccine effectiveness remains unclear.
Preliminary analyses indicate that the vaccination status of cases infected with BA.4 and BA.5 is not significantly different to that of cases infected with BA.2, United Kingdom Health Security Agency had noted on June 24. The body is a government agency responsible for public health protection in the UK.
This means severe disease and death remain at bay for those vaccinated. “The protection conferred by the vaccines likely remains comparable to that observed previously,” the body said.
Concurrently, the US Food and Drug Administration (FDA) has recommended Omicron-specific booster shots, which will include BA.4 and BA.5 sub-variants.
While Omicron and its sub-lineages have dominated for the better part of the last year, what will come next is unpredictable. It could be another Omicron sub-variant or a completely different variant from a distinct SARS-CoV-2 branch.
“Repeat Omicron infections could build broad immunity against successive lineages, creating an opening for a different SARS-CoV-2 variant unfamiliar to people’s immune responses,” Ravindra Gupta, a virologist at the University of Cambridge, was quoted as saying by Nature.
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