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A South African study based on blood samples found that the BA.4 and BA.5 sub-lineages of Omicron were more likely to evade antibodies produced by previous Omicron infections than the immunity provided by vaccinations.
Scientists took blood samples from 39 people infected with Omicron, with 24 people not vaccinated and 15 vaccinated with the Pfizer or the Johnson & Johnson vaccines, Reuters reported.
"The vaccinated group showed about a 5-fold higher neutralisation capacity ... and should be better protected," the study said, according to Reuters.
There was an eightfold decrease in antibody protection in unvaccinated blood samples when exposed to the sub-variants compared to a threefold decrease in the blood samples from vaccinated people.
"Based on neutralisation escape, BA.4 and BA.5 have potential to result in a new infection wave," the study said.
The finding is important because health authorities say cases caused by the sub-lineages are increasing in South Africa to a degree that the nation may be entering a fifth wave of COVID, Reuters said.
Health Minister Joe Phaahla said recently that hospitalizations were increasing but that ICU admissions had not greatly gone up yet.
Reuters. "COVID's new Omicron sub-lineages can dodge immunity from past infection, study says"
Reuters. "South Africa says it may be entering fifth COVID wave"
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Cite this: Ralph Ellis. Omicron Sublineages Evade Immunity From Past Infection - Medscape - May 03, 2022.