Video report by ITV News Meridian's Penny Silvester
A Buckinghamshire school teacher, who is believed to be the most prolific female coronavirus blood plasma donor in the UK, has been described as a superhero.Secondary school science teacher Lizzi Wallace, who had coronavirus at the beginning of the pandemic, has donated her blood plasma 12 times - despite having a fear of needles.
Plasma from people who have recovered from Covid-19 can be transfused into people who are still unwell and struggling to develop their own immune response.
The plasma contains neutralising antibodies which could stop the virus spreading.
Lizzi says her plasma is treated like "liquid gold" as it "could save lives".
She says it is "a really tiny thing for me to do" but it has helped her get her "head around the pandemic".
Hospitals are calling for more people who have had Covid-19 to follow her example and become donors themselves.
What is blood plasma?
Blood plasma is a yellowish liquid that makes up about half of your blood volume. After a virus, your plasma contains antibodies that help fight infection.
What is the process of donating blood plasma?
Donating plasma is similar to giving blood. Instead of the liquid going into a bag, it goes into a machine that spins it and separates the plasma from the blood cells. The blood cells are then given back.