United Blood Services, the area’s nonprofit blood provider, has a third line of defense to safeguard the blood supply from Zika virus.

In addition to following the two standard recommendations of the AABB (formerly the American Association of Blood Banks), United Blood Services will use its computer system to defer blood donors who provide information about travel within the past 28 days to the Caribbean, Mexico or Central or South America.

In line with the AABB recommendations, United Blood Services advises donors to alert the blood center if they develop symptoms that might indicate a viral infection, like Zika, within 14 days of their donation. The CDC lists the most common Zika symptoms as fever, rash, joint pain and conjunctivitis (red eyes). The blood center also has posted signs instructing people to delay their donation if they’ve recently traveled to areas where the mosquito-borne Zika virus is spreading.

“The situation is complex and it’s changing rapidly,” said Dr. Hany Kamel, vice president and corporate medical director for Blood Systems, the national office of United Blood Services. “As we ask every donor our standard questions about travel, we will identify those who should wait. Our computer system will allow us to flag them so they will not be able to donate with us until they’ve been back in the U.S. for 28 days.”

The travel waiting period is expected to reduce the number of eligible donors across the U.S. by an estimated 2 percent, according to a recent survey of community blood centers. Blood centers in states along the border with Mexico will be particularly affected.