Officials in America’s New York state announced earlier this week that two new Omicron sub-variants, named BA.2.12 and BA.2.12.1, had become dominant coronavirus strains in parts of the state.
The New York health department reported that infection rates in central New York, where these strains have become dominant, had for weeks been at least twice the state’s average.
The mutations that these two sub-variants have may help SARS-CoV-2, the virus that causes COVID-19 disease, to enter human cells faster and evade immunity from vaccines and previous infections, according to Andy Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health.
The emergence of new variants or sub-variants in itself is not an issue of concern but the presence of mutations in some of these emerging strains that would give the virus an edge is of concern.
What are variants and sub-variants of a virus?
All viruses evolve and acquire mutations, which lead to the emergence of “variants” of a virus.
These “variants” further split to form sub-lineages called “sub-variants”. The Delta variant that drove India’s deadly second wave is known to have up to 200 sub-variants.
Not all mutations these variants (and sub-variants) have are of concern. However, some mutations allow the virus to spread more effectively, such as in the case of Omicron variant, whereas some mutations lead to increased severity of disease, such as in the case of Delta variant.
It is these kinds of mutations that are of concern.
New Omicron sub-variants in New York spread faster but with no increased severity
The two new Omicron sub-variants are spreading 23-27 per cent faster than the original BA.2 Omicron variant, according to New York state officials cited by The Washington Post.
The increased transmissibility has not so far coincided with increased severity of disease.
“At this time, there is no evidence of increased disease severity by these sub-variants, though the department is closely monitoring for any changes,” said the New York health department in a statement this week.
Johns Hopkins’ Pekosz, cited above in the piece, said, “Whenever we see those mutations, we're a little bit concerned, but it's hard right now to really estimate how big of a concern those variants will be.”
As for cases, the two sub-variants in March accounted for over 70 per cent of reported infections in central New York. The number for April so far is 90 per cent.
Do you need to be worried about these new strains?
These two sub-variants have been discovered in five countries besides the US, according to NPR. These countries are – Canada, the United Kingdom, Australia, Israel and Luxembourg.
In New York, where these sub-variants are concentrated, The Post has noted that infections are approaching levels previously seen during last year’s Delta-fuelled wave.
The current spike is, however, manageable, according to experts. It is also expected as now most restrictions, such as mask requirements, have been lifted.
Earlier, another sub-variant called XE was found that had increased transmissibility.
Experts had at the time said that XE – which should apply to the two strains in New York as well – emerged very quickly after massive Omicron waves, meaning that it would face a strong wall of immunity among people – either from vaccination or from previous vaccination. This would mean that even if it spreads among the population, the severity is expected to be low.
Therefore, while experts and officials are tracking the disease trajectory, the emergence of these two strains in New York is not a subject of immediate concern as no particular rise in severity of disease is observed so far.