People who have recovered from coronavirus are being asked to donate their plasma in South Yorkshire to help save lives.
The plasma can then be given to poorly patients who need help fighting the virus.
Plasma contains antibodies which are created by the body after fighting an infection like Covid-19.
Following a record number of infections since Christmas, more people than ever are thought to have the antibodies.
So far, 3,500 people from Barnsley have volunteered to donate their plasma to the NHS.
More people are being asked to come forward to help with new trials to help treat older people who have coronavirus.