STUDY: Pfizer Vaccine Loses Significant Effectiveness Against Omicron

Pfizer said that a booster dose of their vaccine neutralized the Omicron variant in lab testing, but that the two-dose regimen was significantly less effective.

A third dose increased antibodies 25 times compared to the two doses, the Wall Street Journal reports. Still, two doses may be effective in preventing severe symptoms because immune cells can recognize 80 percent of parts of the spike protein that the vaccine targets.

The findings suggest that three doses will be necessary to produce a similar immune response against Omicron as was given by the first two doses in earlier strains.

“This is very positive news that should make everyone even more motivated to get vaccinated,” Pfizer Chief Scientific Officer Mikael Dolsten said.

Pfizer and BioNTech are working on an Omicron-specific vaccine that they hope to have readily available by March of 2022.

Dolsten said that regardless of how widespread Omicron becomes, booster shots will likely be needed in the future to provide utmost protection. A fourth booster is likely to be needed in the spring or fall of 2022.

“It’s increasingly clear that you need to have a long-term perspective, with continued boosting to have strong, durable immunity,” he said. “If the landscape looks similar to today, we will likely continue to boost with the current vaccine.”