A study looking into alternating Covid-19 vaccine doses launched in the UK. The clinical trial will be the first in the world to determine the effects of using different vaccines for the first and second jab – for example, using Oxford University/AstraZeneca's vaccine for the first dose, followed by Pfizer/BioNTech's vaccine for the second. The innovative research, which is backed by £7 million of government funding, will recruit more than 800 volunteers aged 50 and above. However, the current programme of two doses of the same vaccine over 12 weeks remains unchanged. If the study shows promising results, the government may consider reviewing the vaccine regimen. The trial will last 13 months, but preliminary results are expected around June 2021.