Moderna Rapidly Works Vaccine Upgrade to Target Variants

With the news of COVID-19 variants popping up worldwide, Moderna is actively working to upgrade its vaccine to address them, in particular the recent South African strain.

While Moderna believes its vaccine will be effective against that variant and others, CEO Stephane Bancel told CNBC's "Squawk Box" on Monday, it is "unknowable what will happen in six months, in 12 months."

"Immunity may go down over time," he said, adding the work to address variants is out of an "abundance of caution."

"We cannot be behind — we cannot fall behind this virus."

Moderna has confidence in its data finding its vaccine remains effective against the U.K. variant, but it has also reported antibody levels are "diminished sixfold," the company said.

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