Two new sublineages of the Omicron variant coronavirus can evade antibodies from previous infections well enough to trigger a new wave, but are far less able to thrive in the blood of people who have been vaccinated against Covid-19, South American scientists have found.
Scientists from multiple institutions studied Omicron sublines BA.4 and BA.5 – which the World Health Organization added to its watch list last month. They took blood samples from 39 participants who had previously been infected with Omicron when it first emerged late last year.
Fifteen were vaccinated – eight with Pfizer’s vaccine; seven with J&Js – while the other 24 were not.
“The vaccinated group showed about five times the neutralizing capacity… and should be better protected,” says the study, a preprint of which was published on Weekend.
In the unvaccinated samples, there was a nearly eight-fold decrease in antibody production when exposed to BA.4 and BA.5 compared to the original BA.1 Omicron line. The blood of those vaccinated showed a three-fold drop.
SA could enter a fifth Covid-19 wave sooner than expected, officials and scientists said on Friday, blaming a continued spike in infections that appear to indicate due to the BA.4 and BA.5 omicron subvariants.
Only about 30% of South Africa’s 60 million population is fully vaccinated.
“Based on neutralization flight, BA. 4 and BA.5 have the potential to lead to a new wave of infections,” the study said.