Steve Parsons - WPA Pool/Getty Images A major UK trial exploring the possibility of a mix-and-match approach to Covid vaccination is being expanded to include the Moderna and Novavax jabs. Scientists behind the Com-COV study, led by the University of Oxford, hope that combining vaccines could give “broader, longer-lasting immunity” against the coronavirus and new variants, reports the BBC. Using different brands of vaccination for first and second doses would also give more flexibility to the vaccine rollout. The study is looking for volunteers over 50 who have had a first dose of Pfizer or AstraZeneca. More than 800 people have already participated in the trial, but Professor Matthew Snape, from the Oxford Vaccine Group, is hoping to recruit a further 1,050 volunteers who have received one vaccine dose on the NHS in the past eight to 12 weeks.