But as the immediacy of the deadly events faded, the sleeves came down again, says a new study that highlights the difficulty of encouraging people in this country to become regular blood donors.
"Americans are quick to respond in times of national emergency," says study author Dr. Simone Glynn. "During the Sept. 11 events, there was a tremendous national outpouring of public support that included thousands of people wanting to donate blood."
But only about 30 percent of those people ever came back to give again. "Many first-time donors may not realize that blood is needed every day to save the lives of accident victims or patients with cancer," Glynn says.
The study, reported in the May 7 issue of the Journal of the American Medical Association, tracked blood supplies at five regional centers, which together make up about 8 percent of the nation's blood pool.
In the month before the terrorist attacks, the centers collected roughly 20,000 units of blood per week. That number hit 49,000 in the week following Sept. 11, and remained at about 27,000 or so for several weeks, or about 40 percent more than normal. Nationally, blood banks collected 572,000 units more than usual in the three-month period after the attacks, a larger spike than was seen during the first Gulf War or the 1995 Oklahoma City bombing.
First-time donors usually account for about one-fifth of all blood donated at the five sites. But in the wake of Sept. 11, that figure soared to almost half.
Compared with the month before the attacks, the number of first-time donors jumped more than fivefold in the week after Sept. 11. Repeat donations rose 50 percent, while the rate of repeat donors who had taken a 10-year or longer hiatus from giving blood tripled, from 2 percent to 6 percent of the supply at the banks. As with the San Francisco quake of 1989, the majority of new donors were women.
Despite the encouraging outpouring after the attacks, first-time donors were no more likely to become repeat givers than in the past, with this rate hovering around 30 percent.
The influx of new donors was accompanied by a tripling in the number of blood units infected with potentially serious microbes, including HIV, hepatitis C and hepatitis B. Almost all the increase was due to more detection of hepatitis C, a potentially deadly liver virus. Yet the researchers say this increase wasn't significant and didn't threaten the safety of the blood supply. Nor was it the result of a surge in risky donors, but rather reflected having so many more people willing to give blood.
Dr. Linda Chambers, senior medical officer for the American Red Cross in Washington, D.C., says the study shows the nation's blood screening system worked well both before and after Sept. 11. The Red Cross didn't see an increase in people acquiring infections from blood in the weeks and months after the terrorist attacks, she says.
Although blood banks greatly appreciated the good will and effort of the new donors, Chambers says their donations wouldn't have helped mass casualties on Sept. 11. Instead, these people would have required blood collected in the weeks before the attacks, since blood needs time to be tested and processed.
"The bottom line is that blood donation and the continuous need for blood is not something that's right in front of people day to day," she says. "They think what they give today is going to be available tomorrow."