The US Food and Drug Administration said on Tuesday it may decline to review and process new emergency use authorization (EUA) requests for COVID-19 vaccines for the rest of the pandemic, if a company has not already begun discussions.

So far, vaccines from Pfizer Inc, Moderna Inc and Johnson & Johnson have been authorized for emergency use in the United States.

Novavax Inc has had discussions with regulators and said it does not expect to seek regulatory authorization for its COVID-19 shot in the United States, Britain and Europe until the third quarter of 2021.

Canadian drug developer Medicago said it was in discussions with the FDA for an EUA for its plant-based COVID-19 vaccine candidate, which is enhanced by a GlaxoSmithKline treatment.

AstraZeneca also has discussed plans for its COVID-19 vaccine with US officials. However, the Wall Street Journal earlier this month reported that it was considering skipping US emergency-use authorization and instead pursue the more time-intensive application for a full-fledged license to sell the shot.

AstraZeneca and Novavax did not immediately respond to requests for comment.