Two coronavirus vaccine have proven safe for humans and produced strong immune reactions among patients involved in separate clinical trials, doctors said Monday. The first trial among more than 1,000 adults in Britain found that the vaccine-induced “strong antibody and T cell immune responses” against the novel coronavirus. A separate trial in China involving more than 500 people showed most had developed widespread antibody immune response. The studies, published in The Lancet medical journal, constitute a major step on the road towards a COVID-19 vaccine that is effective and safe for widespread use. The authors of the studies said that they encountered a few adverse side effects from the vaccine candidates. However, they cautioned that more research was needed, particularly among older...