BA.2: What we know about the new Omicron sub-variant

Over the last two months, cases of the SARS-CoV-2 variation Omicron have grown substantially, with several nations witnessing spikes that are higher than earlier forms.

Cases of a sub-variant of Omicron identified as BA.2 are now appearing.

It is more useful to think of BA.2 as Omicron’s sibling rather than as a child of the Omicron variant BA.1 (or B.1.1.529).

What exactly is a variant?

When viruses replicate, they make so many mistakes, especially RNA viruses like SARS-CoV-2. Because they are unable to rectify their faults, they have a tremendous rate of errors, or mutations, and they are continually developing.

A variation is associated with changes in the genetic code of a virus as a consequence of these mutations.

Omicron has amassed more than 30 mutations in the spiking protein, making it a “highly divergent” variation. This has diminished antibody resistance from prior infection and inoculation as well as enhanced the mode of transmission.

Sorting out variations

It will be considered a “variant of interest” if mutations in the genetic code are judged to have the ability to affect features of the virus that make it more hazardous, and there is significant transmission in many nations.

It is labelled a “variant of concern” if a variant of interest is later demonstrated to be more contagious, defy protection from vaccine or past infection, and/or influence the performance of testing or therapies.

Because of its potential to generate increased reinfection frequencies, heightened transmissibility, and lower vaccination protection, the World Health Organization classified Omicron as a variation of concern on November 26.

Lineage of Omicron

A lineage, also known as a sub-variant, is a group of virus variations that are genetically related and descend from a common origin.

B.1.1.529 or BA.1, BA.2, and BA.3 are the three sub-lineages of the Omicron variation.

While the WHO has not classified BA.2, the United Kingdom has classified it as a variation “under investigation.” So, according to WHO standards, it is not yet a variety of concern or alarm, but it is being attentively monitored.

This isn’t the first time that a variation has sub-lineages. The Delta “plus” or AY.4.2, was widely publicised late last year, and then Omicron appeared.

BA.2 is different from BA.1

While the first sequences of BA.2 were presented from the Philippines, the virus’s origin is still unclear. We’ve seen countless cases, including in the United States, the United Kingdom, and Australia.

The precise qualities of BA.2 are still being researched. While there is no proof that it causes more serious disease, scientists are concerned about a few things.

1.It is more hard to distinguish.

The absence of the S gene, often known as “S gene target failure,” helped distinguish Omicron (BA.1) from other variants on PCR tests. In the instance of BA.2, however, that’s not the case.

Some have dubbed this lineage the “stealth sub-variant” due to its inability to be detected in this manner. However, this does not rule out the possibility of using PCR tests to diagnose BA.2. It simply means that when someone’s results are positive for SARS-CoV-2, genome sequencing will take a bit longer to figure out which variant is to blame. As with prior variations, this was the case.

 2. It could be more contagious.

Perhaps most alarming is evidence that BA.2 is more contagious than BA.1, the original Omicron.

According to a preliminary study from Denmark, where BA.2 has fully replaced BA.1, BA.2 increases the susceptibility of the unvaccinated to disease by just over two times when contrasted with BA.1.

According to the researchers, people who have been fully vaccinated are 2.5 times more vulnerable to BA.2 than those who have been booster immunized, and those who have been booster immunised are approximately three times more vulnerable.

The researchers looked at over 2,000 main home cases of BA.2 to see how many instances developed during a seven-day follow-up period.

The secondary attack rate (basically, the likelihood of infection) for households infected with BA.1 was estimated to be 29% versus 39% for those infected with BA.2.This Danish study is currently a draft, which means it hasn’t been peer-reviewed yet, so further research is needed to determine whether BA.2 is indeed more contagious than BA.1.

Variants in the future

New variations, sub-variants, and lineages are likely to emerge in the future. With such high levels of infection, the virus has a lot of opportunities to proliferate and make mistakes or mutations.

Of course, one method to deal with this is to try to delay transmission and reduce the number of susceptible hosts in which the virus can easily proliferate.

The establishment of new varieties and lineages will be slowed by strategies such as social separation and mask-wearing, as well as growing global vaccination rates.