As the world faces an impending wave of COVID cases due to omicron, scientists are racing to assess vaccine efficacy against the new variant.
In a new study from Rockefeller University, researchers reported their comprehensive analysis of omicron’s resistance to antibodies, offering insights about the levels of immunity current vaccines may provide.
The researchers found that omicron is more prone to escape antibodies produced after vaccination or infection than previous variants of SARS-CoV-2.
However, boosters fortify the antibody response sufficiently to deliver a substantial increase in protection.
To assess how well antibodies stand up against omicron, in the study, the researchers mixed 169 plasma samples with a harmless virus bearing the spike protein of the omicron variant, or the spike of the original SARS-CoV-2 for comparison.
They then measured how well the plasma samples neutralize the two variants.
The team found among unvaccinated COVID survivors, and people who had received two doses of mRNA vaccines or one dose of the Johnson & Johnson’s vaccine, the neutralizing ability of blood plasma took a substantial hit from omicron, decreasing 30 to 180-fold (in contrast, the delta variant has been found to cause only a two-fold decrease.)
Moreover, a big fraction of people in these groups showed extremely low levels of neutralizing antibodies, sometimes even below of the level of detection.
But the team found boosters make a remarkable difference. People who received an mRNA booster shot following infection or prior vaccination showed about 30 to 200-fold increases in neutralizing activity against omicron.
In line with the findings of previous studies, this improvement suggests that mRNA boosters increase the levels of antibodies and may promote their ongoing evolution to more effectively target the spike protein.
The findings add to growing evidence that people vaccinated with only two doses of the Pfizer or Moderna mRNA vaccine, or those immunized by coronavirus infection, are less protected against omicron than all previous variants.
Although scientists expect that vaccines will protect many against severe disease and death, boosters will be needed to make this protection more robust and to counter the spread of the virus.
The team says it is time to discard the notion that two doses of mRNA mean ‘fully vaccinated,’ or that people who have had COVID don’t need to be vaccinated.
For more information about COVID, please see recent studies about people with COVID-19 who recover faster with this treatment, and results showing this drug can offer much-needed COVID-19 protection.
The study was posted on medRxiv. One author of the study is virologist Paul Bieniasz.
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