AstraZeneca and Oxford University’s final clinical trials for a coronavirus vaccine were put on hold after a participant had a suspected adverse reaction. AstraZeneca described it as a ‘routine’ pause in the case of ‘an unexplained illness’. The AstraZeneca-Oxford University vaccine is seen as a strong contender among dozens being developed globally. Hopes have been high that the vaccine might be one of the first to come on the market, following successful phase 1 and 2 testing. Phase 3 vaccine trials often involve thousands of participants and can last several years. Although the cause of the illness has not been confirmed, the New York Times reported the volunteer was diagnosed with transverse myelitis, an inflammatory syndrome that affects the spinal cord and can be caused by viral infections.