Many countries don’t have enough donated blood to meet their needs, a recent study suggests.The World Health Organization (WHO) recommends that for every 1,000 people in any country, 10 to 20 blood donations are needed to provide adequate supplies. Blood transfusions save lives and improve health, and the WHO says ensuring a safe and adequate supply of blood should be an integral part of every country’s national healthcare policy.But the study of the blood supply and demands for transfusions based on common health issues in 195 countries found that 119 of them may not have enough blood to meet the population’s needs.“As more people are able to access care in low and middle income countries, the demand for blood transfusions will increase further, and – without financial, structural and regulatory support – will widen the gap we’ve uncovered between global supply and demand of blood,” said Dr. Meghan Delaney, a co-author of the study and a researcher at Children’s National Hospital in Washington, DC.The study is the first to estimate the gap between global supply and demand of blood based on country-specific medical needs, her team writes in The Lancet Haematology.“Other studies have focused on blood safety, such as the risk of transmitting infections such as HIV, but ours is the first to identify where the most critical shortages lie, and therefore where the most work needs to be done by governments to increase donation, scale-up transfusion services and develop alternatives,” said co-author Christina Fitzmaurice from the University of Washington.To calculate the availability of blood worldwide, the researchers used data from a WHO survey on transfusion practices between 2011 and 2013, to which 180 of 195 countries responded.To estimate how this compared to each country’s needs, they calculated the amount of blood needed for 20 different medical conditions based on US data from 2000 to 2014. They also calculated the prevalence of these conditions in each country and then estimated how much blood would be needed to provide a transfusion to every patient in need.The total global blood supply was estimated to be around 272 million units. However, the total global demand in 2017 was approximately 303 million units – a shortfall of around 30 million units. Across the 119 countries with insufficient supply, the shortfall totaled more than 100 million units, which was equal to around 1,849 units per 100,000 people.In most high-income countries, supply could meet demand, but not in many low-income countries.Lower income countries had relatively low demand compared to high-income countries, which can be attributed to a lower disease burden from injuries and chronic diseases. However, these countries also had the greatest estimated shortfalls in supply. The supply of whole blood and of the three components derived from it – red blood cells, platelets and plasma – therefore varied sharply between countries.To meet demand in 2017, assuming that around 1.5 units of blood components can be derived from a donation, 40 countries would require more than 30 donations per 1,000 of the population, rather than the WHO target of 10-20, researchers estimated.One limitation of the study is that researchers based their estimates on ideal blood transfusion practices in the US, which might not reflect what would happen elsewhere, particularly in countries where neglected tropical diseases, malaria and pregnancy and childbirth complications are more severe, researchers note.Still, the results underscore the importance of a safe and secure blood supply and the unmet needs in many parts of the world, Thierry Burnouf of Taipei Medical University in Taiwan, writes in an editorial accompanying the study.“Substantial differences in the availability, safety and quality of blood still exist around the world,” Burnouf writes.