Public responds to NHS amber alert over donor blood stocks- PublishedThe blood-donation service has been inundated with offers of help after putting out an alert, on Wednesday, warning NHS stocks were running critically low in England.O positive is the most common and anyone can receive O negative in an emergency or if their blood type is unknown.Blood supplies have been challenging since the Covid pandemic, because of staff shortages and sickness, and a change in people's behaviour means they are less likely to visit donation centres in towns and cities, according to NHSBT.NHSBT said it was quickly developing a "register your interest" form so it can work with new donors who tried to sign up."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."