More than 1,000 blood donors are still needed in Sheffield to take part in a medical research project.
In the UK, the current waiting period between blood donations is 12 weeks for men, and 16 weeks for women.
During the two-year study men will be asked to donate every eight, 10 or 12 weeks and women every 12, 14 or 16 weeks.
The study aims to find the best time period between donations, to allow people to give more regularly and increase the supply of blood.
Researchers hope to get 50,000 people from around the country involved. Sheffield’s Blood Centre is nearly two-thirds of the way to meeting its target.
Anyone who wishes to be in the study must be able to give blood, be aged 18 or over, and have access to the internet with a valid email address.
The study is being led by researchers from Oxford and Cambridge universities alongside NHS Blood and Transplant.
Call 0300 123 2323 to take part.
More information is available at: http://www.bbc.co.uk/news/uk-england-25404797
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