A vaccine developed by the University of Oxford and British drugmaker AstraZeneca has shown promising immune responses against COVID-19 in both young and old adults in its ongoing clinical trials in the U.K., said the pharmaceutical company on Monday. As the novel coronavirus has killed more than 1.15 million people across the globe and is predicted to kill more than 500,000 Americans before the end of February, an effective vaccine is viewed by many as a silver bullet in the fight against the unprecedented virus. “It is encouraging to see immunogenicity responses were similar between older and younger adults and that reactogenicity was lower in older adults, where the COVID-19 disease severity is higher,” an AstraZeneca spokesman reportedly said.