'A little person in history' - teens who signed up to test Covid-19 vaccine

Two adolescent siblings in the United States who signed up for a coronavirus vaccine trial said they did it because they wanted to make their own small contribution to history.

Nathan Williams, 17, and his sister Delilah, 12, signed up for the trial after spending months in pandemic isolation. Their mother, Melanie Williams, is a nurse and hospital administrator who works in a ward dealing with Covid-19 patients...