The highly contagious Omicron variant of the SARS-CoV-2 virus, the most common form of which is known as BA.1, is currently the cause of almost all coronavirus infections worldwide, although spikes in COVID-19 cases have already peaked in some countries, Reuters reported. .
Scientists are now seeing an increase in cases caused by Omicron’s close cousin known as BA.2, which is starting to overtake BA.1 in parts of Europe and Asia.
What do we know about the new stealth sub-variant?
Globally, BA.1 accounted for 98.8% of sequenced cases submitted to the Global Initiative for the Sharing of Avian Influenza Data (GISAID) as of 25 January. However, according to the World Health Organization (WHO), several countries are already reporting increases in cases of the sub-variant known as BA.2.
In addition to BA.1 and BA.2, WHO lists two other sub-options “under the hood” of Omicron: BA.1.1.529 and BA.3. All of them are closely related genetically, but are characterized by mutations that can change their behavior.
Trevor Bedford, a computer virologist at the Fred Hutchinson Cancer Research Center who tracks the evolution of SARS-CoV-2, tweeted on Friday that BA.2 accounts for approximately 82 percent of cases in Denmark, 9 percent in Denmark. UK and 8 percent in the United States, based on an analysis of GISAID data and case counts from Oxford University’s Our World in Data project.
The BA.1 option from Omicron is a bit easier to use than the previous ones. The reason is that BA.1 is missing one of the three target genes used in a conventional PCR test. By default, it is assumed that cases in which this pattern is observed are caused by BA.1.
BA.2, also known as the “invisible” subvariant, does not have the same missing target gene. Instead, scientists observe it in the same way as in previous versions, including Delta, tracking the number of viral genomes submitted to public databases such as GISAID.
As with other variants, BA.2 infection can be detected with home coronavirus tests, although they cannot determine which variant is responsible, experts say.
Some early reports suggest that BA.2 may even be more contagious than the highly contagious BA.1, but to date there is no evidence that it is more likely to evade the protection provided by vaccines.
Based on preliminary data, the Danish health authorities have calculated that BA.2 may be 1.5 times more contagious than BA.1, although it is unlikely to cause more severe illness. The question of whether people infected during the BA.1 wave will be protected from BA.2 remains a key one, American experts say.
The good news is that vaccines and booster doses still “protect people from hospitalization and death,” the US experts added.