Prime Minister Boris Johnson has said a Wrexham laboratory could provide "salvation for humanity" when it starts producing coronavirus vaccines.
Mr Johnson visited Wockhardt UK Ltd on Monday, which he said would be making the Oxford/AstraZeneca vaccine if it is approved.
The PM said "if we're lucky" the vaccine could be available within weeks.
It was a very exciting and "moving moment", he added.
The Wrexham plant has the capability to produce around 300 million doses of vaccine a year and preparations to produce 150,000 vials a day of the vaccine have been under way for weeks.
As the drugs were being developed, preparations for transferring large vats of the vaccine into single-dose vials have been ramped up.
Ravi Limaye, managing director, said the company expected to start delivering the first doses of the vaccine soon.
"We are immensely proud to have been selected to partner with the UK government on this project," he said.
"We have a sophisticated sterile manufacturing facility and a highly skilled workforce."
Unite union official Dave Griffiths said the Wrexham site had taken on 40 staff to deal with the demand and planned to produce 150,000 vials a day, five days a week.