As more and more countries in Europe suspend the rollout of the AstraZeneca vaccine, fears have been raised over the jab and a potential link to dangerous blood clots. As it stands the European Medicines Agency and World Health Organisation have stated that there is no link between the vaccine and blood clots. But how did these fears arise, and what could a delay in the vaccine rollout mean in the fight against Covid-19? The Independent's science correspondent Samuel Lovett explains exactly what is going on with the AstraZeneca vaccine.