Massachusetts-based Moderna has released preliminary data from a trial of its COVID-19 vaccine candidate, delivered as two doses several weeks apart, that shows 94.5% effectiveness in protecting against the virus. The trial is currently following 30,000 participants who have received either the candidate or placebo. Out of 95 infections observed during the trial, only 5 infections were found in the group that had received the vaccine. No significant serious concerns were noted; fatigue, muscle aches and injection-site pain were the main side effects. Canada has a firm commitment for 20 million doses (immunizing 10 million people), with the option of an additional 36 million. While the news is encouraging, the final report is needed to determine whether the benefit is consistent among all groups (for example the elderly) and how long immunity lasts.