The mother of a child who needs regular transfusions is urging donors to continue to give blood over Christmas.
Vicky Flintoft, who lives with her family in Harrogate, North Yorkshire, is backing NHS Blood and Transplant's calls for donors to make an appointment to donate.
Her son Archie, 5, has relied on donors to keep him alive since he was a baby.
Archie has Diamond Blackfan Anaemia, a rare condition which means he can't make his own red blood cells.
Mrs Flintoft said: "Archie is a typical five-year-old. He's a massive fan of superheroes and a real livewire. To look at him you'd never know there was anything wrong.
"Archie knows his bones don't make blood so he needs blood from other people. Before a transfusion he is unsettled and bad tempered, but once he has that good blood in him the happy, lively little boy who loves cuddles is back.
"Blood changes everything for Archie - It is literally his lifeline."
Many people will still need transfusions over the festive period as treatment for a blood condition or cancer, or due to surgery, childbirth or an accident.
The NHS is keen to build blood stocks ahead of the winter peak.
The only two days of the year that blood donations are not collected are Christmas Day and New Year's Day, with appointments available on Christmas Eve and Boxing Day
Mrs Flintoft continued: "Before Archie I thought blood was only needed in emergencies.
"Now I know there are many people like him with life-threatening conditions who depend on blood all year round, even at Christmas.
"I cannot put my gratitude to blood donors into words. Without them, my son wouldn't have left hospital as a baby. Donors give him life - they are superheroes in my eyes. I would especially thank those who make the extra effort to donate over Christmas to help people like Archie."
As well as existing donors, NHS Blood and Transplant is calling on people who have registered but not yet donated to make their first appointment.
Giving blood is exempt from COVID-19 travel restrictions, even during a full lockdown.
Jon Latham, assistant director of donor relationship services at NHS Blood and Transplant, said: "We know that giving blood can slip off the to-do lists over Christmas and new year. But we need our loyal donors more than ever right now so we can keep hospitals supplied with lifesaving blood.
"The demand for blood has reached near pre-pandemic levels, yet we have extra winter challenges this year with the added pressure of COVID-19. In the summer months there was less demand from hospitals for blood, but this winter could be particularly challenging for us because that is no longer the case, and we now have donors spaced out and fewer beds in use as well as the usual winter pressures like colds, flu and bad weather.
"We need anyone who is fit and healthy and who can donate to please book and make an appointment. Our sessions are open as usual with extra safety measures in place and extra appointments have been added to help us meet these winter demands."
To book appointments and check the latest guidance on COVID-19 and giving blood call 0300 123 23 23, download the NHS Give Blood app, or visit the website blood.co.uk