Unvaccinated people who have recovered from COVID-19 are at a higher risk of contracting the new BA.4 and BA.5 subvariants of Omicron than their vaccinated counterparts, a new study from South Africa claims.
According to the findings, the two new COVID strains can effectively evade antibodies in convalescent patients.
The study further found that the reproduction rate of BA.4 and BA.5 — cases of which have already been detected in Israel — is diminished among fully vaccinated individuals.
Scientists examined blood samples from 39 people who had previously been infected with Omicron, of which 15 were vaccinated — eight with Pfizer's shot and seven with Johnson & Johnson's vaccine — while the other 24 were not vaccinated at all.
The vaccinated were 5 times more likely to evade reinfection with the newer substrains compared to their unvaccinated counterparts.
Scientists also found that antibody production crashed nearly eightfold in those who only had natural immunity after being exposed BA.4 and BA.5 compared to the original BA.1 Omicron variant, whereas antibody levels fell threefold in those who had both natural immunity and vaccine protection.
The study further stated that BA.4 and BA.5 have the potential to stoke “a fresh wave of infections,” which some fear might hit South Africa sooner than previously expected, owing to gradually clambering daily COVID cases and the country's low vaccine turnout.
And while South Africa reports rising hospitalizations, there is still no data available on the mortality rate of the new strains.
While Omicron and its offshoots effectively supplanted the Delta variant's spot as the primary and most common coronavirus strain, a new Israeli study hinging on wastewater samples claims that "Omicron levels will decrease until eliminated, while Delta variant will maintain its cryptic circulation."