Thousands of people offered to donate blood in response to an amber alert over critically low stocks, NHS Blood and Transplant has revealed.
Most appointments to donate blood this week are now fully booked, but the NHS is still appealing for people with O negative or O positive blood to come forward for priority booking.
O negative blood is the type that can be given to everyone and is used in emergencies when a person’s blood group is unknown.
As thousands of people have come forward, a lack of staff means many will not be able to book appointments despite good intentions.
NHSBT said they are quickly developing a “register your interest” form so it can work with new donors who tried to sign up and is urging all donors to come back in a few weeks to check for more appointments.
More than 10,000 appointments to donate blood over the next few weeks were booked in the past 24 hours.
On the blood website, 100,000 people queued to offer help, with some waiting up to an hour to book.
Thousands rush to donate blood as stocks plummet PA images
More than 166,000 people also visited the website overall, while 7,500 people registered as new donors on Wednesday making it the highest daily spike in new registrations in 20 years.
While appointments are limited, NHSBT are urging people to keep checking for appointments in the future, including in November and December, especially at permanent donor centres in towns and cities which have extended hours and greater capacity.
An NHSBT spokeswoman said: “This is an amazing response from the public and we have been reminded in the last 24 hours of the incredible goodwill and spirit of the public towards helping patients in times of great difficulty.
“While the amber alert isn’t a widespread donor appeal, we want to say a huge thank you to existing donors and those who came forward in their thousands yesterday to register for the first time.
“We’d like to extend a special thanks to those donors who called us to express their empathy and offering to do anything they could to help.
“Staffing and appointment availability continues to be our biggest challenge and the amber alert will remain in place for at least the next four weeks, where unfortunately limited appointment availability to donate will be commonplace due to staffing levels.
“We know this can be frustrating for donors who want book an appointment right now to help.
“Please be assured that we are doing our utmost to prioritise appointments for blood types most in demand right now and in the near future, but we only have so many appointments available in the short term, so it’s a fine balancing act.
“If you are an O neg group blood donor please call our customer contact centre to book a priority appointment – we are asking all other blood donors to help by filling the appointments available in the coming few weeks at our permanent donor centres.
People can visit blood.co.uk or use the blood app to check if there are appointments nearby.
O positive or O negative donors are being asked to call 0300 123 23 23 for a priority appointment.