The European Medicines Agency on Thursday identified severe allergic reactions as a potential side effect of Novavax Inc.'s COVID-19 vaccine.
The vaccine was authorized by U.S. regulators Wednesday, and its product label in the United States warns against administering the shot to people with a history of allergic reactions to any components of the shot.
Shares of Novavax fell 20.3% to $55.72 in morning trading, along with the broader market and other COVID-19 vaccine makers. Novavax shares are usually volatile.
The EMA said it would also update the product information for the vaccine to add unusual or decreased feeling in the skin as a new side effect.
Only 250,000 doses of Novavax's COVID vaccine, Nuvaxovid, have been administered in Europe so far since its launch in December, according to the European Centre for Disease Prevention and Control.