This statement seems a big deal: "There were no hospitalised or severe cases in anyone who received the vaccine" Is that also true of the Pfizer and Moderna trials? Are the various trials measuring 'effectiveness' in the same way? Is there a standard for 'effectiveness' in these Covid-19 trials? It will take some digging and real effort to compare the risks and benefits of the various vaccines coming to market.
Maybe its chance that none of those 39 got really sick. I'm not sure what the age breakdown of trial participants was- were the people in the oxford trial younger? Did the distribution match the distribution from the mRNA trials? I have no idea.