Another week, another set of preliminary results from a Covid-19 vaccine trial. This time it is the Moderna vaccine candidate, mRNA-1273. And, to judge by the figures put out by the company this morning, it has outdone the Pfizer vaccine in its efficacy. Out of the 30,000 people involved in the phase three trial (half of whom were given the vaccine and half of whom were given a placebo), 95 went on to contract Covid-19. Of those who became infected, 90 were in the control group and only five had been given the vaccine. Eleven participants had a severe case of Covid, all of whom were in the control group.