According to a recent study published in the journal Allergy, there was virtually no antibody protection against the Omicron variant in people who were double-vaccinated and those who have recovered from infection by previous strains of the SARS-CoV-2 virus. Only individuals vaccinated with a third or booster dose of the COVID-19 vaccine form antibodies that can partially block Omicron.

Researchers from the Medical University of Vienna studied and examined an Austrian subpopulation of vaccinated and recovered individuals for their antibody status and protection against the Wuhan, Delta and Omicron variants. They adapted a test developed for the previous variants for Omicron. The test detects whether the virus can bind to the receptor on human cells via its receptor-binding domain (RBD), which is used by SARS-CoV-2 to enter human cells via the ACE2 receptor on cells.

The researchers said that the RBD differed only slightly in all previously known SARS-CoV-2 variants so the currently available vaccines protected against infection by the previous variants. But Omicron was the first variant that differed to a great extent from the previous variants in RBD. So the currently available vaccines were very less effective or ineffective in protecting against Omicron.

The study showed that people with the previous infection from COVID and the twice vaccinated group developed antibody protection against Delta, but the antibodies were not able to block the receptor-binding domain against Omicron. Rudolf Valenta who led the research team said that the blockade of Omicron was better in those individuals who had received the third vaccination. Also, among 20% of the people, no protection was observed. 

Valenta further said that until a broadly effective combination vaccine is developed that could protect against both the previous variants and Omicron, only repeated vaccinations with the existing vaccines would provide some protection. He also said that the protective effect achieved by vaccination could be evaluated with special tests that could rapidly adapt to new virus variants.

Source: News Nine