Washington, USA January 16 ANI An international team of researchers recently examined the sensitivity of Omicron to antibodies compared to the currently dominant Delta variant.
The new COVID 19 Omicron variant is more transmissible than the Delta variant. Its biological characteristics are still relatively unknown.
In South Africa, the Omicron variant replaced the other viruses within a few weeks and resulted in an increase in the number of cases diagnosed. In various countries, the doubling time for cases is approximately 2 to 4 days. Omicron was detected in dozens of countries, including France, and became dominant by the end of 2021.
In a new study supported by the European Union's Health Emergency Preparedness and Response Authority, HERA scientists from the Institut Pasteur, Belgium Orleans Regional Hospital, Hospital Europeen Georges Pompidou AP-HP and Inserm, the sensitivity of Omicron to antibodies was studied in a study by the European Union's Health Emergency Preparedness and Response Authority.
The aim of the study was to examine the efficacy of therapeutic antibodies, as well as antibodies developed by individuals previously infected with SARS-CoV- 2 or vaccine, in order to neutralize this new variant.
The KU Leuven researchers isolated the Omicron variant of SARS-CoV-2 from a nasal sample of a 32-year-old woman who developed moderate COVID 19 a few days after returning from Egypt. The isolated virus was immediately sent to researchers at the Institut Pasteur, where therapeutic monoclonal antibodies and serum samples from people who had been previously exposed to SARS-CoV-2 were used to study the sensitivity of the Omicron variant.
The researchers used rapid neutralization assays developed by the Institut Pasteur's Virus and Immunity Unit on the isolated sample of the Omicron virus. The multidisciplinary effort involved Institut Pasteur's virologists and specialists in the analysis of viral evolution and protein structure, along with teams from Orleans Regional Hospital and Hospital Europeen Georges Pompidou in Paris.
The scientists started by testing nine monoclonal antibodies used in clinical practice or currently in preclinical development. Six antibodies lost all antiviral activity, and the other three were 3 to 80 times less effective against Omicron than Delta.
A combination developed by Roche called Bamlanivimab Etesevimab, a combination developed by Lilly Casirivimab Imdevimab and known as Ronapreve and Regdanvimab developed by Celtrion, has no longer had any antiviral effect against Omicron. The Tixagevimab and Cilgavimab combination developed by AstraZeneca under the name Evusheld was 80 times less effective against Omicron than against Delta.
We demonstrate that this highly transmissible variant has a significant resistance to antibodies. Most of the therapeutic monoclonal antibodies currently available against SARS-CoV-2 are inactive, said Olivier Schwartz, the co-author of the study and head of the Virus and Immunity Unit at the Institut Pasteur.
The researchers found that the blood of patients previously infected with COVID-19, collected up to 12 months after symptoms, and that of individuals who had received two doses of the vaccine, taken five months after vaccination, barely neutralized the Omicron variant. The sera of individuals who had received a booster dose of Pfizer, analyzed one month after vaccination, remained effective against Omicron.
In cell culture assays, five to 31 times more antibodies were required to neutralize Omicron, compared with Delta. These results shed light on the effectiveness of vaccines in protecting against severe forms of the disease.
We need to study the length of protection of the booster dose. Olivier Schwartz said that vaccines might become less effective in protecting against contracting the virus, but they should continue to protect against severe forms of the disease.
This study shows that the Omicron variant hampers the effectiveness of vaccines and monoclonal antibodies, but it also shows the ability of European scientists to work together to identify challenges and potential solutions. While KU Leuven was able to describe the first case of Omicron infection in Europe using the Belgian genome surveillance system, our collaboration with the Institut Pasteur in Paris allowed us to carry out the study in record time, said Emmanuel Andre, co-founder of the National Reference Laboratory and the genome surveillance network for COVID 19 in Belgium.
There is still a lot to do but thanks to the support from the European Union's Health Emergency Preparedness and Response Authority, HERA, we have reached a point where scientists from the best centres can work together to better understand and more effective management of the pandemic, he said.