Johnson & Johnson’s experimental one-shot Covid-19 vaccine has generated a long-lasting immune response, as per results of an early safety study, which were made public on Thursday. Neutralising antibodies were produced in more than 90% of participants, within 29 days after receiving the shot, according to the report, and all participants formed antibodies within 57 days. The immune response lasted for the full 71 days of the trial. The one-shot vaccine generates more antibodies than a single dose of other front-runner Covid-19 vaccine, all of which are two-shot regimens. J&J’s progress is being closely watched by top infectious disease experts because the vaccine has the potential to become the first that can protect people after just one shot, making mass-vaccination campaigns much easier.