Moderna pops, then drops after it says booster shot increases protection against Omicron

• Moderna soared as much as 9% Monday after it said its booster increased protection against Omicron.
• A third dose of Moderna's vaccine resulted in a 37-fold increase in protection against the variant.
• Moderna's authorized booster shot is half the dose of each of its first two vaccine shots.
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Moderna stock soared as much as 9% on Monday after it said its COVID-19-vaccine booster increased protection against the Omicron variant. Shares ultimately gave up those gains and fell by as much as 1% amid a broad stock-market sell-off.

A third dose, which is half the dose of each of the first two vaccine shots, resulted in a 37-fold increase in antibody protection against the fast-spreading Omicron variant, the company said.

"The dramatic increase in COVID-19 cases from the Omicron variant is concerning to all. However, these data showing that the currently authorized Moderna COVID-19 booster can boost neutralizing antibody levels 37-fold higher than pre-boost levels are reassuring," Stéphane Bancel, the CEO of Moderna, said.

The results have yet to be peer-reviewed, and Moderna added that its original two-dose vaccine regimen did not provide a strong response to the Omicron variant.

To quickly combat the rise of the Omicron variant, Moderna said it planned to quickly advance an Omicron-specific booster candidate into clinical testing, in case it becomes necessary.

"Given the long-term threat demonstrated by Omicron's immune escape, Moderna will also continue to develop an Omicron-specific variant vaccine (mRNA-1273.529) that it expects to advance into clinical trials in early 2022 and will evaluate including Omicron in its multivalent booster program," Moderna said in a press release Monday.

"We will also continue to generate and share data across our booster strategies with public health authorities to help them make evidence-based decisions on the best vaccination strategies against SARS-CoV-2," Bancel added.

The strong booster results against Omicron are welcome news for Moderna investors, who have experienced a 40% decline since the stock topped out around $497 in August. The stock reversed its gains to losses on Monday morning, falling about 1%. Still, shares of Moderna are up 187% year to date.