Johnson & Johnson subsidiary Janssen is moving ahead with a late-stage clinical trial of its COVID-19 vaccine candidate, beginning with recruiting 6,000 participants in the United Kingdom with plans to eventually enrol 30,000 people in six countries worldwide. One source of optimism is that the vaccine delivers its protection through the same spike protein mechanism that Pfizer’s candidate, recently found to have 90% effectiveness in preliminary data, uses. Trial organizers hope to recruit a participant pool that reflects groups hit hardest by the disease, including the elderly and minority groups.