The EU has introduced controls on the export of COVID-19 vaccines from the bloc to Northern Ireland - sparking an angry response from First Minister Arlene Foster.
The EU is accusing pharmaceutical companies of prioritising vaccine supplies to the UK.
A low-cost, widely used anti-inflammatory drug improved survival in patients with Covid-19, the first treatment to show life-saving promise months into the pandemic.
Professor Peter Horby, Professor of Emerging Infectious Diseases and Global Health, has said that dexamethasone is the 'only drug shown to reduce mortality'.
Around 90% of experimental vaccines never reach the clinic because of problems in development or manufacture.