The US government's revealed computer hackers have targeted plans to distribute Covid-19 vaccines.
A number of companies that are part of the 'cold supply' chain have received emails containing malicious software since September.
The Pfizer-BionTech vaccine - which has been authorised for use in the UK - needs to be kept at minus 70 degrees.
Sky's Deborah Haynes is in Washington, where officials believe a country could be behind the attack.
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