Novavax Inc.’s stock tumbled 16% early Wednesday after the company said the FDA has placed a clinical hold on its COVID-19-and-flu combination and stand-alone flu vaccine candidates, following a case of motor neuropathy in a participant in a mid-stage trial.

The so-called clinical hold is due to a single report of nerve damage in a patient who received the combination shot in a phase two trial.

Novavax said federal regulators put a clinical hold on its application for a combination Covid-19 and influenza vaccine and standalone flu inoculation, sending shares down sharply.