Is Omicron ‘subvariant’ more virulent? Concerns over BA.2 as India reports 530 samples to GISAID
- A total of 40 countries, including India, Britain, Denmark, have reported 8,040 sequences of Omicron sublineage to GISAID.
British health authorities have identified hundreds of cases of the latest version of the Omicron variant, dubbed BA.2, amid concerns over its transmissibility. The UK Health Security Agency (UKHSA) designated the Omicron variant sub-lineage as a variant under investigation due to increasing numbers of BA.2 sequences both domestically and internationally.
Britain has so far confirmed 426 cases of Omicron BA.2 by conducting Whole Genome Sequencing (WGS), the earliest case reported on December 6, 2021. With 146 confirmed cases of BA-2. London has reported the highest number of Omicron subvariant in the UK, followed by the South East (97).
While there is still uncertainty around the significance of the changes to the viral genome, early analyses, according to UKHSA, suggest an increased growth rate compared to the original Omicron lineage BA.1.
“[H]owever, growth rates have a low level of certainty early in the emergence of a variant and further analysis is needed,” the health agency added.
A total of 40 countries have reported 8,040 sequences of Omicron sublineage to GISAID, a primary source that provides open access to genomic data of influenza viruses and the coronavirus. The first sequences were submitted from the Philippines. With 6,411 sequences, most samples of BA-.2, so far, have been uploaded from Denmark. India has reported 530 samples of Omicron subvariant, followed by Sweden with 181 and Singapore with 127.
Is it more virulent?
Dr Meera Chand, Covid-19 Incident Director at UKHSA, said the nature of viruses is to evolve and mutate so the emergence of new variants is expected as the pandemic goes on.
“So far, there is insufficient evidence to determine whether BA.2 causes more severe illness than Omicron BA.1, but data is limited and UKHSA continues to investigate,” Chand said.
French epidemiologist Antoine Flahault expressed surprise over the rapidity with which the sub-variant of Omicron has taken hold in Denmark, reported AFP.
"(France) expected a spike in contaminations in mid-January: It didn't happen and perhaps that is due to this sub-variant, which seems very transmissible but not more virulent" than BA.1, he said, stressing that countries have to be alert to the latest development as scientists ramp up surveillance.
Citing early observations from India and Denmark, Tom Peacock, a virologist at Imperial College, London, said that there is no dramatic difference in severity compared to BA.1.
In a series of tweets, he stressed that "we do not currently have a strong handle on ... how much more transmissibility BA.2 might have over BA.1. However, we can make some guesses/early observations."
He added that the latest variant should not call into question the effectiveness of existing vaccines.