Tokyo - The Pirola variant of Covid-19, also known as BA.2.86, has been identified as one of the most "highly immune evasive" variants in a recent Japanese study published in The Lancet's November issue.

Despite its presence in India since August, the Pirola variant didn't cause a significant surge in cases. Furthermore, reported cases of this variant remained relatively low in various continents, including Europe, North America, and Africa, indicating that it might be quietly spreading worldwide. The World Health Organization (WHO) is closely monitoring this variant.

The study, titled "Transmissibility, infectivity, and immune evasion of the SARS-CoV-2 BA.2.86 variant," concluded that BA.2.86 is exceptionally proficient in evading the immune system.

Researchers from multiple institutes, including the Institute of Medical Science at the University of Tokyo, Japan, found that the blood samples from individuals who received additional vaccine doses or different types of vaccines showed limited effectiveness against the new BA.2.86 variant. Additionally, antibodies that previously fought against the virus proved ineffective against this new version.

According to the study, "The sera obtained from individuals vaccinated with third-dose monovalent, fourth-dose monovalent, BA.1 bivalent, and BA.5 bivalent mRNA vaccines exhibited very little or no antiviral effects against BA.2.86. Additionally, the three monoclonal antibodies that worked against the original BA.2 variant did not show antiviral effects against BA.2.86."

The study also indicated that BA.2.86 may possess greater fitness than the currently circulating XBB variants, including EG.5.1, making it a more stable variant.

The Pirola variant, also known as BA.2.86, differs significantly from XBB and the parental BA.2 variant, bearing over 30 mutations in the spike (S) protein, many of which are associated with immune evasion.

Researchers discovered that when they tested blood samples from individuals with XBB breakthrough infections, the antibodies were less effective at combatting the new BA.2.86 version when compared to another variant called EG.5.1. This highlights the resilience of BA.2.86 against the immune system, making it one of the most challenging variants in terms of immune evasion.