Back in December, the UK said that prioritising first doses of the vaccine for as many people as possible would protect the greatest number of at-risk people in the shortest possible time. But the WHO, the European Medicines Agency and the FDA in the US have all advised against extending the time between first and second doses.
Danny Altmann, Professor of Immunology at Imperial College London. He says even though the UK started its vaccination programme well, its strategy of varying the gap between doses raises questions.
Watch Euronews' full report in the player above.