Novavax (NVAX) shares plummeted 5.02% in Thursday's pre-market trading session following news of delayed approval for its COVID-19 vaccine and growing concerns about its efficacy. The biotech company, which offers the only non-mRNA COVID-19 booster option in the United States, faces an uncertain future as its current batch of boosters is set to expire on April 30.

The U.S. Food and Drug Administration (FDA) has postponed its decision on Novavax's full approval, which was initially due by April 1. The delay comes in the wake of controversial statements made by Health Secretary Robert F. Kennedy Jr., who cast doubt on the efficacy of single-antigen vaccines like Novavax's for respiratory illnesses. However, the FDA has signaled that approval might still be possible if Novavax agrees to produce additional clinical data on the vaccine's efficacy post-approval.

Despite the setback, thousands of Americans, particularly those with long COVID and those who cannot or will not take mRNA vaccines, continue to campaign for Novavax's approval. Patient advocacy groups have mobilized, submitting written comments to the Centers for Disease Control and Prevention and reaching out to FDA officials. The uncertainty surrounding the vaccine's future availability and the ongoing debate about its effectiveness appear to have shaken investor confidence, contributing to the sharp decline in Novavax's stock price.