Confirmed cases of two new Omicron sub-variants — known as BA.4 and BA.5 — have emerged in several countries, according to the World Health Organisation (WHO).
The agency’s experts, working alongside infectious disease researchers around the world, are currently tracking these two sub-strains closely to figure out whether they are more infectious or pathogenic.
WHO has added BA.4 and BA.5, the newer siblings of the original BA.1, BA.2, BA.1.1 and BA.3 Omicron variants, to its list for monitoring.
What do we know about BA.4 and BA.5?
There are a few things already established by researchers about the two new strains.
Ankara University virologist Abdulkadir Yilmaz stated in a tweet: "BA.4 and BA.5 are 63-84 per cent more contagious than BA.2, the most contagious virus in human history, and have the L452R mutation, which is associated with high pathogenicity. They are more likely to be pathogenic than BA2. They seem much more contagious."
VIRULENCE is the disease-producing power of an organism, the degree of pathogenicity within a group or species.
Will BA.4 and BA.5 lead to more trouble?
Another expert pointed out the specific "L452R" mutation found in both BA.4 and BA.5 strains, which was also present in Delta, Kappa and Epsilon variants.
Harvard University epidemioligst Dr Eric Feigl-Ding stated in a thread: "The L452R is a known troublemaker mutation shared by both BA.4 and BA.5.
Pointing to data from South Africa, Feigl-Ding added: "The good thing is that you can find BA.4 and BA.5 indirectly again using a PCR S gene dropout shortcut test again (you couldn’t with BA.2). To be clear, these are just very early detections in SA which has good sequencing. Cases hasn’t gone up yet, but then again, these two variants haven’t hit 60% or more yet. Wait & see. But I did warn L452R variants on the rise last week — here it was. Now we know it’s BA4 and BA5."
What is the current dominant strain?
BA.2, a sub-variant of Omicron and known as the most contagious virus in human history (before BA.4 and BA.5), is currently the dominant strain globally, representing nearly 94 per cent of all sequenced samples from PCR-positive patients.
The WHO is also tracking BA.1.1 and BA.3, due to their “additional mutations that need to be further studied to understand their impact on immune escape potential".
How many cases of BA.4 and BA.5 have been monitored?
So far, only “a few dozen” cases of BA.4 and BA.5 have been reported to the global GISAID database, according to WHO.
What countries have confirmed BA.4 cases?
From January 10 to March 30, the UK's Health Security Agency said last week that BA.4 had been found in the following countries/territories:
- South Africa
These sublineages are responsible for an increasing share of sequenced cases in South AFrica from early March, according to mutation detectives using open-source biology databases to track them.
Despite the increase in the percentage of genomes, BA.4 and BA.5 are not causing a spike in infections in SA (South Africa). The same is seem for hospitalisation and deaths, which SA is at a record low.
A genomics expert noted there has been no increase in the number of new COVID-19 cases in the country. “Despite the increase in the percentage of genomes, BA.4 and BA.5 are not causing a spike in infections in SA. The same is seem for hospitalisation and deaths, which SA is at a record low,” said Tulio de Oliveira, a bio-informatics professor who runs gene-sequencing institutions at two South African universities, in a tweet.
What countries have confirmed BA.5 cases?
All the BA.5 cases were in South Africa as of last week.
On Monday (April 11, 2022) Botswana's health ministry said it had identified four cases of BA.4 and BA.5 — all among people aged 30 to 50 who were fully vaccinated and experiencing mild symptoms.
What do we know about BA.2?
WHO said it’s now the dominant strain. BA.2 now represents nearly 94 per cent all sequenced cases and is more transmissible than its siblings, according to the agency.
There has been no increase in the number of COVID-19 infections in South Africa, a genomics expert noted. “Despite the increase in the percentage of genomes, BA.4 and BA.5 are not causing a spike in infections in SA. The same is seem for hospitalisation and deaths, which SA is at a record low,” said Tulio de Oliveira, a bio-informatics professor who runs gene-sequencing institutions at two South African universities, in a tweet.
Does BA.2 cause severe disease?
Since it was first identified in November 2021, BA.2 has been spreading around the globe.
While it’s an extra-contagious version of the Omicron variant — virologists say it doesn't seem to cause more severe disease. The evidence so far suggests it is no more likely to cause severe COVID than other Omicron sub-variants.
Where is BA.2 now dominant?
In many countries across Asia and Europe, BA.2 has proven its dominance. Moreover, in the US and more than 60 other countries, BA.2 has almost completely overtaken other coronavirus sub-variants.
Why was BA.2 given the “stealth” nickname?
It was given the “stealth" nickname because it looks like the earlier Delta variant on certain PCR tests, according to Kristen Coleman at the University of Maryland School of Public Health. On the other hand, the original Omicron, is easy to differentiate from Delta because of a genetic quirk.
In rare cases, early research indicates BA.2 can infect people even if they've already had an omicron infection.
Do vaccines work against Omicron BA.1 and BA.2?
COVID-19 vaccines appear just as effective against both BA.1 and BA.2, offering strong protection against severe illness and death.
COVID-19 vaccines appear just as effective against both
What about XE?
Health officials also are tracking other variants including XE — a combination of BA.2 and BA.1, the original Omicron — that was first identified in January 2022 in the United Kingdom. The WHO is keeping tabs on XE but has not yet deemed it a “variant of concern” or "variant of interest”.
Do vaccines work against Omicron BA.3, BA.4 and BA.5?
Since only a few dozen cases of these sub-strains had been reported, there’s no data on the ability of new sub-strains to “escape” immunity conferred by WHO-approved vaccines.