Omicron BA.4 and BA.5 can Dodge Immunity from Infection

Omicron sub-variants BA.4 and BA.5 can avoid immunity induced by both previous COVID infection and vaccination, and are distinct from other Omicron lineages.

Omicron sub-variants BA.4 and BA.5 can avoid immunity induced by both previous COVID infection and vaccination.

According to researchers from the Africa Health Research Institute in South Africa, the findings could signal a fresh wave of infections by the BA.4 and BA.5, Bloomberg reported.

Omicron Variant of COVID-19
Omicron variant is a mutated strain of coronavirus (SARS-CoV-2) with faster transmissibility and enhanced virulence compared to the original COVID-19 virus.

‘BA.4 and BA.5 are estimated to have originated in mid-December 2021 and early January 2022, respectively.’

Last month, scientists at Centre for Epidemic Response and Innovation (CERI) in South Africa detected the two new sub-variants of the highly contagious Omicron variant.

In a series of tweets, the Director of CERI Tulio de Oliveira revealed that "BA.4 and BA.5 are distinct from other Omicron lineages."

Omicron Sub-Variants

Besides seven provinces in South Africa, the sub-variants have also been detected in more than 20 countries including Australia, Austria, Belgium, China, Israel, Denmark, France, Germany, Pakistan, the UK, US and Switzerland, de Oliveira wrote on Twitter.

In the pre-print study, researchers at the Institute analysed blood samples from unvaccinated 24 people infected with the original Omicron variant. The team also tested the sublineages against samples from 15 vaccinated people, eight of whom had Pfizer shots and seven who had received Johnson & Johnson’s vaccines.

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The findings showed an almost eight-fold drop in neutralizing antibody production when tested against the BA.4 and BA.5 sublineages, the Bloomberg report said.

Samples from people who were vaccinated showed about a threefold decrease, according to the study.

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"The low absolute neutralization levels for BA.4 and BA.5, particularly in the unvaccinated group, are unlikely to protect well against symptomatic infection," the researchers said in the study.

"This may indicate that, based on neutralization escape, BA.4 and BA.5 have potential to result in a new infection wave," they added.

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The study comes amid a fresh surge of infections in South Africa, where Omicron was first identified in the country along with neighbouring Botswana in November last year.

On Saturday, South Africa recorded 6,527 new cases and a test positivity rate of 21.5 percent, compared with 581 cases and a positivity rate of 4.5 percent on March 28.

While hospitalizations are rising gradually, there hasn’t been a noticeable increase in deaths, Waasila Jassat, a public health specialist at South Africa’s National Institute of Communicable Diseases, was quoted as saying.

Source-IANS