Written By: Longjam Dineshwori | Updated : March 5, 2022 11:50 AM IST
Omicron, the highly transmissible variant of SARS-CoV-2, was responsible for the biggest surge in Covid-19 cases in many countries. So far, three Omicron subvariants have been identified: namely BA.1, BA.1.1 and BA.2. Several studies have indicated reduction in Covid-19 vaccine effectiveness against Omicron and its variants. A new study by scientists at Columbia University and the University of Hong Kong has also revealed that mRNA vaccines and antibody therapies are less effective against all identified Omicron subvariants.
The study, published in the journal Nature, mentioned that only one currently authorised antibody treatment could retain its activity against all Omicron subvariants, i.e. adequately treat all Omicron subvariants. It's bebtelovimab, which is the latest monoclonal antibody to receive FDA Emergency Use Authorisation.
In laboratory experiments, the researchers found that all three subvariants of Omicron exhibited a strong resistance to most monoclonal antibodies tested. Out of 19 antibodies tested, 17 were found ineffective against the BA.2 subvariant.
For the study, the team collected sera samples from individuals immunised with one of two available mRNA vaccines. Then then tested the efficacy of these vaccines and 19 monoclonal antibodies against the known Omicron subvariants.
They observed a loss of neutralisation activity against BA.1.1 and BA.2 in blood samples from those who had received two mRNA shots. However, the decline in neutralisation was less prominent in blood samples from individuals who had received three mRNA shots, the researcher said, emphasising the importance of booster shots for sustaining immunity.
David D. Ho, Professor of Medicine at Columbia University Vagelos College of Physicians and Surgeons, noted that new variants of coronavirus are challenging the effectiveness of current vaccines, and narrowing our treatment options. He underscored the need to devise novel strategies to contain this ever-evolving pathogen and "don't relax prematurely."
The Omicron variant of SARS-CoV-2 was first identified in November 2021. Among the three Omicron subvariants, BA1.1 is currently the dominant one, making up around 40 per cent of all Omicron cases sequenced globally.
BA.1 cases have declined since December, while BA.2 subvariant currently represents only 10 per cent of all Omicron cases globally.
With inputs from agencies
