A study from the Karolinska Institutet shows that the coronavirus variant BA.2.75.2, a subvariant of omicron, more easily bypasses neutralizing antibodies in the blood and is resistant to several monoclonal antibody treatments. This means an increased risk of sars-cov-2 infection this winter, unless the new updated bivalent vaccines can strengthen the immunity of the population. The results have been published in the journal The Lancet Infectious Diseases.
– Although antibody immunity is not completely gone, BA.2.75.2 showed a much more dramatic resistance than previous variants we studied, which was largely driven by two mutations in the surface protein’s receptor-binding domain, says the study’s corresponding author Ben Murrell , assistant professor at the department of microbiology, tumor and cell biology at Karolinska Institutet.
The study shows that antibodies in 75 randomly selected blood donors in Stockholm were only about one-sixth as effective at neutralizing BA.2.75.2 compared to the now dominant variant BA.5. The blood samples were taken on three occasions: In November last year before omicron was discovered, in April after a large wave of infections in the country and in late August to early September after BA.5 became dominant.
Only one of the clinically available monoclonal antibody treatments tested, bebtelovimab, was able to effectively neutralize the new variant, according to the study. Monoclonal antibodies are used as antiviral drugs to treat people at high risk of severe covid-19.
BA.2.75.2 is a mutated version of another omicron variant, BA.2.75. Since it was discovered earlier this fall, it has spread to several countries but so far still represents a minority of registered cases.
Risk of more infections
– We now know that this is just one of several new variants with similar mutations that are likely to dominate in the near future. This means that we can expect the number of infections to increase this winter, says Ben Murrell.
Some uncertainties remain. It is unclear whether the new variants will lead to an increase in hospitalizations. And while current vaccines generally had a protective effect against severe disease in the case of omicron infection, there is still a lack of data on how well the updated covid vaccines protect against the very latest variants.
– We expect they will help, but we don’t know how much, says Ben Murrell.
The study was carried out in collaboration with researchers at ETH Zurich in Switzerland and Imperial College London in the UK.
The research was funded by SciLifeLab, the Erling-Persson Foundation and the EU’s Horizon 2020 research and innovation programme. Daniel J. Sheward, Gunilla B. Karlsson Hedestam, and Ben Murrell hold intellectual property rights associated with antibodies that neutralize omicron variants.
“ Omicron sublineage BA.2.75.2 exhibits extensive escape from neutralizing antibodies .” Daniel J. Sheward, Changil Kim, Julian Fischbach, Kenta Sato, Sandra Muschiol, Roy A. Ehling, Niklas K. Björkström, Gunilla B. Karlsson Hedestam, Sai T. Reddy, Jan Albert, Thomas P. Peacock, Ben Murrell, The Lancet Infectious Diseases , correspondence, online October 13, 2022, doi: 10.1016/S1473-3099(22)00663-6