Booster dose inactivates the Omicron variant, study finds

Five to 31 times more antibodies were needed to neutralize Omicron, the study said (Representational)


An international team of researchers recently studied the sensitivity of Omicron to antibodies in comparison to the currently dominant delta variant. The study about this edition has been published in the ‘Journal of Nature’.

The new COVID-19 Omicron variant is more transmissible than the Delta variant. However, its biological characteristics are still relatively unknown.

In South Africa, the Omicron version replaced other viruses within a few weeks and there was a sharp increase in the number of diagnosed cases. Analysis in different countries indicates that the doubling time of cases is around 2 to 4 days. Omicron has been detected in dozens of countries, including France, and becomes effective 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 and the Vaccine Research Institute, KU Leuven (Leuven, Belgium), Orléans Regional Hospital, in collaboration with the Hospital European Georges Pompidou (AP- HP) and Inserm studied the sensitivity of Omicron to antibodies in comparison to the currently dominant delta variant.

The aim of the study was to characterize the efficacy of the therapeutic antibody in neutralizing this new variant, as well as antibodies developed by individuals previously infected or vaccinated with SARS-CoV-2.

Scientists at KU Leuven isolated the Omicron version of SARS-CoV-2 from a nasal sample of a 32-year-old woman who developed moderate COVID-19 days after her return from Egypt. The isolated virus was immediately sent to scientists at the Institut Pasteur, where therapeutic monoclonal antibodies and serum samples from people who had been vaccinated or who had been previously exposed to SARS-CoV-2 were used to study the susceptibility of the Omicron variant. was done to.

The scientists used rapid neutralization assays developed by the Institute Pasteur Virus and Immunity Unit on isolated samples of Omicron virus. This collaborative multidisciplinary effort included teams from the Orléans Regional Hospital and Hospital European Georges Pompidou in Paris, as well as virologists and experts from the Institut Pasteur in viral evolution and analysis of protein structure.

The scientists began testing nine monoclonal antibodies used in clinical practice or currently in preclinical development. Six antibodies all lost antiviral activity, and the other three were between 3 and 80 times less effective against Omicron than Delta.

The antibodies bamlanivimab/etacevimab (a combination developed by Lilly), casirivimab/imdevimab (a combination developed by Roche and known as Ronaprev), and regdanvimab (developed by Celtrion) no longer had any antiviral effect against Omicron. The Tixagevimab/Cilgavimab combination (developed by AstraZeneca under the name Evusheld) was 80 times less effective against Omicron than Delta.

Olivier Schwartz, co-final author of the study and head of the virus, commented, “We showed that this highly permeable variant acquired significant resistance to antibodies. Most currently available therapeutic monoclonal antibodies against SARS-CoV-2 are neutralizing.” Huh.” Immunity Unit at Institut Pasteur.

The scientists observed that blood from patients previously infected with COVID-19, collected up to 12 months after symptoms appeared, and that individuals who received two doses of the vaccine five months after vaccination barely neutralized the Omicron variant. But those who received a booster dose of Pfizer had their sera taken a month after the vaccination, which was effective against Omicron.

In cell culture assays, five to 31 times more antibodies are required for neutralizing Omicron than for Delta. These results help to shed light on the continued efficacy of vaccines in protecting against severe forms of the disease.

Olivier Schwartz explained, “We now need to study the length of protection of booster doses. Vaccines probably become less effective in providing protection against contracting the virus, but they should continue to protect against severe forms.” “

“This study shows that the Omicron variant impairs the effectiveness of vaccines and monoclonal antibodies, but it also demonstrates the challenges and the ability of European scientists to work together to identify potential solutions. While at KU Leuven Omicron was able to describe the first case of infection. Europe is using the Belgian Genome Surveillance System, our collaboration with the Institut Pasteur in Paris has enabled us to carry out this study in record time,” said study co-author Commented end author Emmanuel André, Professor of Medicine at KU Leuven (Catholice Universitt Leuven) and head of the National Reference Laboratory for COVID-19 and the Genome Surveillance Network in Belgium.

“There is still much work to be done, but thanks to the support of the EU Health Emergency Preparedness and Response Authority (HERA), we have clearly reached the point where scientists from the best centers can work in synergy And we can move forward towards a better understanding of the pandemic and more effective management,” Emmanuel said.

The scientists concluded that multiple mutations in the Omicron variant’s spike protein enabled it to largely evade the immune response. Ongoing research is being done to determine why this variant is more transmissible from person to person and to analyze the long-term effectiveness of booster doses.

(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)