mRNA-based COVID-19 Vaccine Boosters Induce Neutralizing Immunity Against SARS-CoV-2 Omicron Variant

January 16, 2022/BioValleyBIOON/---The coronavirus SARS-CoV-2, which causes COVID-19, is wreaking havoc globally.In a new study, researchers from the Ragon Institute in the United States and other research institutions found that additional doses from Moderna orPfizerThe company's development of an mRNA COVID-19 vaccine booster aims to provide immunity against the SARS-CoV-2 Omicron variant. They noted that the conventional vaccination regimen of existing mRNA COVID-19 vaccines in the United States does not generate antibodies capable of recognizing and neutralizing the Omicron variant.The relevant research findings were recently published in the journal Cell, with the paper titled "mRNA-based COVID-19 vaccine boosters induce neutralizing immunity against SARS-CoV-2 Omicron variant”。

In late November 2021, health officials in South Africa reported that a previously unknown variant of SARS-CoV-2 was rapidly spreading across the country. The variant, named Omicron by the World Health Organization (WHO), was soon proven to be more transmissible than the Delta variant, which had previously been responsible for the majority of COVID-19 infections. "There is an urgent need to determine whether current vaccines can stop the Omicron variant," said Dr. Alejandro Balazs, corresponding author of the paper and head of a lab at the Ragon Institute that studies how to generate immunity against infectious diseases.

In order to find the answer,Balazs collaborated with a research team, including the first author of the paper, Dr. Wilfredo F. Garcia-Beltran, a clinical science researcher at the Ragon Institute. The first step was to construct a harmless version of Omicron called a pseudovirus, which could be used in the laboratory to evaluate the effectiveness of three existing COVID-19 vaccines in the United States. These include two doses of Pfizer's mRNA COVID-19 vaccine, two doses of Moderna's mRNA COVID-19 vaccine, and one dose of Johnson & Johnson's COVID-19 vaccine. The pseudovirus constructed by Balazs and his colleagues mimics the behavior of the Omicron variant, which has 34 mutations on the "spike" protein of the Omicron variant. Scientists believe that these mutations may be part of the reason for Omicron’s rapid spread worldwide.

Image from Cell, 2022, doi:10.1016/j.cell.2021.12.033.

Next, Garcia-Beltran collaborated with colleagues from Massachusetts General Hospital (MGH) to collect blood samples from 239 individuals who had been fully vaccinated with one of the three COVID-19 vaccines. The study participants included employees of the Brigham Comprehensive Healthcare System in Massachusetts and residents of Chelsea, Massachusetts. Garcia-Beltran stated, "It was important for us to involve a diverse population in this study. In accordance with the recommendations of the U.S. Centers for Disease Control and Prevention (CDC), the participants included 70 men and women who received a third booster dose of either the Pfizer or Moderna mRNA COVID-19 vaccine."

These blood samples were used to measure how effectively each vaccine induced protective immune responses against the Omicron pseudovirus, as well as the Delta variant and wild-type SARS-CoV-2, with these immune responses generated in the form of antibodies. Their findings were striking. Balazs said, "When we used samples taken from individuals recently vaccinated with two doses of an mRNA COVID-19 vaccine or one dose of Johnson & Johnson’s COVID-19 vaccine, we detected very little neutralization of the Omicron pseudovirus. However, people who received three doses of an mRNA COVID-19 vaccine showed a very strong neutralizing effect against the Omicron variant."

It is still unclear why booster shots of mRNA COVID-19 vaccines significantly enhance immune protection against the Omicron variant, but Garcia-Beltran said one possibility is that the additional dose generates antibodies that bind more tightly to the spike protein, increasing their effectiveness. Additionally, booster shots of mRNA COVID-19 vaccines may produce antibodies targeting regions of the spike protein common to all forms of SARS-CoV-2. Garcia-Beltran said both theories could be true.

Balazs pointed out that this three-dose mRNA vaccination regimen—two standard doses of Pfizer or Moderna mRNA COVID-19 vaccines followed by a booster dose—provides lower levels of neutralizing antibodies against Omicron compared to those against the SARS-CoV-2 wild-type strain or the Delta variant. However, the findings strongly support the CDC’s recommendation that a COVID-19 vaccine booster is suitable for individuals aged 16 and above. (Bioon.com)

References:

Wilfredo F. Garcia-Beltran et al. mRNA-based COVID-19 vaccine boosters induce neutralizing immunity against SARS-CoV-2 Omicron variant. Cell, 2022, doi:10.1016/j.cell.2021.12.033.