New Omicron sub-variants can escape vaccine, natural immunity; have potential to trigger new wave – Experts explain
Two new sublineages of the Omicron coronavirus variant, detected by South African scientists last month, can evade vaccine immunity and antibodies from prior infections, and may trigger a new wave, according to a study.
The World Health Organization last month added the two new Omicron's sublineages - BA.4 and BA.5 - to its monitoring list.
South African scientists from multiple institutions, who were examining the sublineages, however, noted that the two are far less able to thrive in the blood of people vaccinated against COVID-19.
"Based on neutralisation escape, BA.4 and BA.5 have potential to result in a new infection wave," the study said.
They examined blood samples of 39 participants who were previously infected by Omicron. Of 39, 15 were vaccinated - eight with Pfizer's shot; seven with J&J's -- while the other 24 were not.
"The vaccinated group showed about a 5-fold higher neutralisation capacity ... and should be better protected," said the study, a pre-print of which was released over the weekend.
In the participants who were not inoculated, there was an almost eightfold decrease in antibody production when exposed to BA.4 and BA.5, compared with the original BA.1 Omicron lineage.
New sub-variants appear to be more infectious
According to experts, the two new sub-variants of Omicron appear to be more infectious than previous strains.
The BA.4 and BA.5 sublineages appear to be more infectious than the earlier BA.2 lineage, which itself was more infectious than the original omicron variant, Tulio de Oliveira, who runs gene sequencing institutes South Africa, recently said in a series of tweets.
“Our main scenario for Omicron BA.4 and BA.5 is that it increases infections but that does not translate into large hospitalizations and deaths," he said.
So far, the sub-variants have been detected in South Africa, Botswana, Belgium, Germany, Denmark, and UK.
Last month, the WHO said that, so far, no change was seen in the severity or transmissibility of BA.4 or BA.5. "There are less than 200 sequences available so far and we expect this to change...We are tracking (the virus) very closely to see if there is any uptick in case detection, but (so far) we haven't seen any change in epidemiology or severity," WHO lead epidemiologist Dr Maria Van Kerkhove had said at a press event.
The WHO has been tracking the two sub-variants because of their "additional mutations that need to be further studied to understand their impact on immune escape potential".