New Omicron sublineages show an ability to evade antibodies from earlier infection, a new Covid study has found.
But the deadly virus is far less able to thrive in the blood of people vaccinated.
Experts at a South African laboratory believe it could signal a fresh wave of infections in the country in the months ahead as with only 30 per cent of the popular fully jabbed.
Blood samples from people who had been infected with the original Omicron variant saw a big drop in neutralising antibody production when tested against the BA.4 and BA.5 sublineages that were discovered this month in South Africa.
“The low absolute neutralisation levels for BA.4 and BA.5, particularly in the unvaccinated group, are unlikely to protect well against symptomatic infection,” the researchers said.
Image:
SIPA USA/PA Images)“This may indicate that, based on neutralisation escape, BA.4 and BA.5 have potential to result in a new infection wave.”
On Saturday South Africa recorded 6,527 new cases and a test positivity rate of 21.5%.
The scientists from multiple institutions were examining Omicron's BA.4 and BA.5 sublineages, which the World Health Organisation recently added to its monitoring list.
They took blood samples from 39 participants previously infected by Omicron when it first showed up at the end of last year.
Image:
Anadolu Agency via Getty Images)Fifteen were vaccinated - eight with Pfizer's shots, seven with Johnson & Johnson’s - while the other 24 were not.
"The vaccinated group showed about a 5-fold higher neutralisation capacity, and should be better protected," they added.
In the unvaccinated samples, 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.
Image:
Getty Images)Blood from the vaccinated people showed a threefold decrease.
South Africa may be entering a fifth Covid wave earlier than expected, officials and scientists announced on Friday.
They are blaming a "sustained" rise in infections that seems to be driven by the BA.4 and BA.5 Omicron sub-variants.
Only about 30% of South Africa's population of 60 million is fully vaccinated.
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