‘Omicron also shows immune escape’

AHMEDABAD: More than two years after the pandemic peaked — vaccination doses and herd immunity notwithstanding — the Covid-19 virus is down but not out. Many are still contracting Covid despite two or three doses of vaccination or their history of the infection. That is because the virus is also adapting to changing situations and has become less lethal but more infectious. Thus, the Omicron variant of Covid has also shown immune escape like its predecessor the Delta variant, indicates the latest study by an international consortium including Gujarat Biotechnology Research Centre (GBRC) from India. Omicron has been the dominant variant in Gujarat and India since the beginning of the year.
The paper ‘Evaluation of immune evasion in SARS-CoV-2 Delta and Omicron variants’ by Armi Chaudhari, Madhvi Joshi, Dinesh Kumar, Amrutlal Patel, Kiran Lokhande, and Chaitanya Joshi from GBRC among others was published recently in Elsevier’s Computational and Structural Biotechnology Journal. Other authors are from Stanford University School of Medicine, University of Pastdam in Germany, University of Warsaw in Poland, University of California Berkeley, and Harvard Medical School.
“The molecular dynamic (MD) simulation data and virus neutralization assays revealed that Omicron also exhibits immune escape, as antigenic beta-sheets appear to be disrupted,” the study said. “The results of the present study demonstrate the higher possibility of immune escape and thereby achieved better fitness advantages by the Delta and Omicron variants.” The study stressed the fact that both Delta and Omicron variants had higher transmissibility compared to wildtype (original) strain of the virus.
“We carried out simulations on the models of Omicron and Delta to understand the mechanism of immune escape, and found that in Delta, it was N-terminal domain (NTD) on the spike protein through which the virus docks on human cells,” said a researcher. “In Omicron, the role of receptor-binding domain (RBD) is more prominent. Thus, we can say that the mechanism of immune escape has changed over time.”
The researchers said that the implications of the study are about the spread in the future. A researcher said that due to vaccination and herd immunity, the impact of Covid-19 is no more than flu today for a majority of the population. “But it will take a relatively longer time for nearly-zero cases, as the virus is constantly mutating, adapting to the host situations,” said a researcher. “While Delta had a relatively free run, Omicron had to surmount challenges of better immune system. Thus, we have seen far more variants for Omicron and will see more in the time to come before a completely new variant emerges.”