Two new variants of the Omicron coronavirus strain pose a danger of triggering a new wave of COVID-19as they can dodge antibodies, according to a study carried out by South African scientists.
However, they are far less able to spread in the blood of people vaccinated against COVID-19, the report also observes.
The scientists studied Omicron's BA.4 and BA.5 variants which are on the WHO's monitoring list.
They took blood samples from 39 participants previously infected by Omicron. Fifteen of them were vaccinated 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 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. Blood from the vaccinated people showed a threefold decrease.
South Africa may be entering a fifth COVID wave earlier than expected, officials and scientists said on Friday, blaming a sustained rise in infections that seems to be driven by the BA.4 and BA.5 Omicron sub-variants, according to a Reuters report from Johannesburg.
Only about 30% of South Africa's population of 60 million is fully vaccinated.
