Many new vaccines are being tested to thwart the pandemic coronavirus, which infects a human cell (brown) with deadly efficiency to produce new copies (pink).
By Jon CohenScience’s COVID-19 reporting is supported by the Pulitzer Center.As desperately as the world wants a shot that provides protection from the new coronavirus afflicting one country after another, proving that a vaccine works safely can be painfully slow.
Clinical trials start with small numbers of people and at first only look for side effects and immune responses, slowly building up to a large study that tests efficacy—a process that will take at least 1 year for the new virus.