SAN FRANCISCO (WABC) -- In a poignant and impressive show of support and solidarity in the wake of the Orlando nightclub shooting, Americans began lining up outside blood banks from the shell-shocked city to Virginia, Texas, Wisconsin and beyond.
But missing from those lines -- or eventually turned away -- were gay and bisexual men who can only donate blood if they've been celibate for a year. It is a long-standing policy that many call discriminatory and outdated, but the Food and Drug Administration has long maintained that a ban on gay blood donations helps prevent the spread of HIV. And all blood centers have to follow that mandate.
"Blood donations policy should be based on science, not stigma," said Anthony Hayes, of HIV/AIDS prevention, care and advocacy group GMHC.
On Tuesday, ironically World Blood Donor Day, LGBT activists gathered on the steps of City Hall to push for an end to the ban. The event had been previously planned, but organizers say the Orlando shooting highlighted the urgency of the issue.
HIV specialist Dr. Howard Grossman was among those calling on the FDA to come up with donor guidelines that make sense.
"The rules should be based on actual behavior, not who your having sex with," he said. "We don't blanket ban whole other groups, except for gay men, because of who they're having sex with."
At least one company is supporting the call for change by canceling its annual employee blood drive and planning to ask others to do so.
"We cannot sanction and sponsor an event that would stigmatize some of our employees, particularly that works against our common goal of increasing and safeguarding our blood supply," AppNexus' Nithya Das said.
Later in the year, the Blood Equality Campaign will bring together a panel of experts to take on the issue of blood safety, donations and a path to change. Organizers say the FDA has declined to attend.
At least 700 people showed up at the OneBlood donation center near the Pulse nightclub Sunday. In all, 5,300 gave blood throughout OneBlood's donation network in Florida and three other southern states.
Blood equality rally held at City Hall in wake of Orlando shooting
ORLANDO MASS SHOOTING