New York CNN Business  — 

Fears about the Omicron variant of Covid-19 rattled the world’s financial markets Friday and early Monday morning. But shares of the major coronavirus vaccine makers were getting a boost from the latest pandemic jitters.

Moderna (MRNA) soared more than 20% during Black Friday’s abbreviated session of trading on Wall Street and were up another 10% Monday, too.

BioNTech (BNTX) surged 14% Friday and were up 3% Monday while the European drug maker’s vaccine partner, Big Pharma leader Pfizer (PFE), gained 6% Friday but fell a bit Monday.

Shares of Novavax (NVAX), another company that is seeking approval from the United States’ Food and Drug Administration for its Covid vaccine, were up 9% Friday but gave back a big chunk of those gains Monday, falling 8%.

The stocks of two other vaccine manufacturers — Johnson & Johnson (JNJ) and AstraZeneca (AZN) — moved only modestly Friday and Monday.

Investors are hoping that the major vaccine makers will be able to quickly update their Covid vaccines so that it can offer protection for the Omicron variant.

Moderna said Friday that it “will rapidly advance an Omicron-specific booster candidate” while Pfizer has stressed that it could hopefully have an update of its vaccine ready in 100 days if Omicron proves to be resistant to its current vaccine.