Johnson & Johnson has finalized a deal with the European Commission for 400 million doses of its COVID-19 vaccine candidate, Ad26.COV2.S.

Ad26.COV2.S is derived from a common cold virus that is modified to carry a gene from the SARS-CoV-2 virus, which causes the immune system to develop resistance to the coronavirus. 

Dosing in a phase 3 trial of Ad26.COV2.S  was recently suspended following a reported adverse event. The late-stage trial, which began in September, aims to enroll 60,000 participants across three continents to evaluate a single vaccine dose vs. placebo.