If it’s not one thing then its another…now some blood centers are reporting an unusual drop in collections because too many potential donors are sick with the H1N1 virus. Blood drives in some high schools and corporate offices have had to be scaled back or canceled because of high levels of absenteeism.  And to make the situation even a bit worse some centers say a growing number of donors are calling a day or two after giving blood to say they’ve come down with flu-like symptoms, forcing the centers to dispose of the blood as part of government regulations. Researchers in a government-funded study are testing samples of these donors’ blood for viremia, the medical term for virus in the blood.

Blood Bag
Unlike infectious diseases such as HIV/AIDS, hepatitis C and West Nile virus, colds and flu aren't believed to be transmitted by blood. But some studies indicate that more virulent strains can be present in the blood before flu symptoms show up. "When you get into strains that are pandemic, the rules don't necessarily apply," says Matthew Kuehnert, director of the Office of Blood, Organ and other Tissue Safety at the Centers for Disease Control and Prevention.

Medical officials say there is enough blood to comfortably supply the 15 million units used annually in trauma units, operating rooms and elsewhere. But blood centers have begun working with the federal government and hospitals to put emergency planning measures in place, such as allocating blood only to the sickest patients, should the pandemic worsen or return in a more virulent form next spring.

Once blood is collected, it is separated into red blood cells, platelets and plasma, and then undergoes 14 different tests, including 11 for infectious agents such as HIV to ensure its safety. Blood is then labeled by type, stored at appropriate temperatures, and distributed to hospitals as needed. Centers are concerned that the supply they keep on hand—typically three to five days’ worth of blood—could quickly become stretched if more donors fall ill.

America's Blood Centers, an association of independent facilities that collects about half of the U.S. blood supply, says that 27% of its member centers are reporting a decrease in overall collections due to swine flu.

Nearly a quarter of the centers reported that collections have dropped at high schools, which have been one of the fastest-growing sources of blood donations in recent years as more states allow students as young as 16 to donate. And more than 15% of centers reported declines in blood collections from colleges and from corporations, where layoffs and plant closings have hurt blood drives.

Partly offsetting the reduced collections is lower blood demand as more people put off costly elective surgeries due to the tough economy, says Richard Benjamin, medical director of the Red Cross, which supplies about 43% of the nation’s blood. But a looming worry is the upcoming holiday season, when it is traditionally harder to recruit donors.

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Medical experts generally don't believe colds and flu can be transmitted by blood, and no case of seasonal influenza transmitted by blood has ever been reported in the U.S. But there also has been little active surveillance for flu in the blood supply.

The National Institutes of Health since the late 1980s has funded studies of blood safety through a program known as the Retrovirus Epidemiology Donor Study, or Reds, to determine the prevalence of HIV among blood donors and the risks of transmitting HIV and other viruses via transfusions. As part of a second phase of that study, researchers in 2006 began examining whether influenza virus could be detected in blood. Philip Norris, associate director of the Blood Systems Research Institute in San Francisco, and a lead investigator on the project, says testing of hundreds of blood donors at risk for seasonal influenza hasn’t revealed any evidence of influenza virus in the blood. He says his group is repeating the study with new blood samples “in case our assumption that H1N1 will behave like seasonal influenza is wrong.”

Food and Drug Administration regulations require blood centers to turn away would-be donors who have any symptoms of illness. And any donor who falls ill shortly after giving blood is asked to notify the center where they donated so their blood can be removed from inventory. So far, the swine flu has turned out to be less infectious than medical experts at first feared. Still, because many patients who get blood transfusions have weak immune systems, a flu infection transmitted through the blood could be extremely dangerous, increasing their risk of death.