The Zika virus poses a grave threat to the nation’s blood supply while also driving up the cost of blood products. And with the virus likely to spread by mosquito in much of the Sun Belt, its impact can only be expected to grow.
Blood collection is an enormous business, generating annual revenue measured in the billions of dollars nationally. The primary customers are hospitals, which pay upward of $200 for red blood cells and a good bit more for platelet units. The shelf life of blood is limited; platelets last only five days, while red blood cells will “date out” in 42. It’s too expensive to freeze blood, so the entire system operates on a just-in-time basis, a delicate balance of supply and demand in which the supply is dependent on the small share of Americans who donate, said Dr. Louis Katz, chief medical officer at America’s Blood Centers, a trade group.
Zika threatens to upset that balance. Blood collection centers are routinely screening donors to determine the likelihood of carrying the virus, asking them to defer a donation for 28 days if they have recently traveled to areas where Zika is present. But 80 percent of those infected show no symptoms, according to the Centers for Disease Control and Prevention. That means relying on such a questionnaire isn’t foolproof, because a donor positive for Zika could inadvertently donate tainted blood after a month’s time.
Meanwhile, the nation’s blood supply is enduring a 30-year low, since millennials haven’t embraced donation with the same dedication as baby boomers, said a spokesperson for the South Texas Blood and Tissue Center of San Antonio. While 38 percent of the population could donate blood, less than 10 percent of Americans actually do, according to the American Association of Blood Banks, the standard-setting body for the industry.
"We don't want to lose any"
In the past, the deferral rate has ranged from 2 percent in the summer to 4 percent in the winter, based on findings in a soon-to-be-published study Katz co-authored. Those rates were based on donors’ travel in 2014 and 2015 to countries outside the U.S. where dengue fever and the chikungunya virus exist. The geography of those tropical diseases aligns with the Zika zone. But with the emergence of mosquito-borne Zika in the U.S., and far greater rates of domestic travel, he expects those figures to increase significantly.
Even at 4 percent or less, the impact is huge.
“If we lose 2 percent, we have to replace it,” Katz said. “And that’s not easy to do.”
At Bloodworks Northwest of Seattle, the largest collection center in the Northwest, a Zika questionnaire has led to a deferral rate of 1 percent to 2 percent, according to spokesperson Dave Larsen. And that's not a negligible amount. For the Mississippi Valley Regional Blood Center, based in Davenport, Iowa, losing 2 percent of donations would translate to 60 units per week.
“That’s a good-sized blood drive for us,” said spokesperson Kirby Winn. “We don’t want to lose any.” The center’s service area includes St. Louis and Cedar Rapids, Iowa.
Miami is ground zero for Zika, having seen the first cases of transmission believed to be caused by mosquitoes. Its primary blood-collection agency, OneBlood, had to suspend collection for a few days to prevent entry of the virus into its supply. That, in turn, prompted a brief national response from other agencies to keep its stock full. The Mississippi Valley Regional Blood Center, for example, sent 50 units. Puerto Rico required a much larger and sustained resupply operation when collection was suspended there in early March and mainland blood centers were airlifting 5,000 units a week.
The halt in collections in Miami didn’t have an outsized impact on OneBlood because the impacted area had donated 304 units in the prior year, said Dr. Riga Reik, chief medical director. Like other collection centers in the South, OneBlood isn’t relying solely on questioning donors about recent travels. Reik said it is testing all donations, which total close to 1 million units per year in Florida, Georgia, Alabama and South Carolina.
But testing costs add up
The test costs $7.50 to $8 per unit, according to Martin Grable, president and CEO at the Community Blood Center of the Carolinas in Charlotte. For the Community Blood Center, the cost of testing will reach almost $1 million per year.
The American Red Cross started testing for Zika on June 20 in five Southeastern states. The organization is expanding the test to California, Texas, Arizona and Oklahoma because of the risk of mosquito-borne transmission in those states. It has tested roughly 48,000 donations; none were positive, a spokesperson said. A charge for the test is tacked on to a hospital’s tab for blood products.
One surprising snag from the paperwork aspect of donation is seen at the South Texas Blood and Tissue Center. About 20 percent of donors refuse to sign a consent form allowing Zika testing of their donation. The center, which became the second in the nation to implement testing, still distributes the blood to hospitals. It’s clearly identified as untested, and hospitals can use it for lower-risk patients and in emergencies, said spokesperson Julie Ann Vera.
Federal regulations govern how the collection agencies deal with the threat. Tony Hardiman, life cycle leader for blood screening at Roche Molecular Systems Inc. of California, said collection centers must provide donors with approved documents concerning information-sharing and how donors who test positive for Zika are handled. Collection centers must agree to the paperwork requirements when they contract with Roche for testing. The process is subject to approval by an institutional review board to make sure there are no concerns about how donors are screened.
Roche’s lab test can be completed in eight to 12 hours. The company is setting up testing laboratories in South Carolina, Florida, Texas and Louisiana to perform the assay. The last time a threat to blood safety drew a similar response was the appearance of the West Nile virus in the U.S. in 2002-03, Hardiman said.
Another biopharma company, Hologic Inc., also won approval from the Food and Drug Administration to provide Zika screening. The company designed the test used by the Red Cross.
The test hasn’t yet received full scientific confirmation of its accuracy, but the threat of the virus required its use before it was fully vetted.
“I’m highly confident the test can pick up very low levels of the virus,” said Dr. Steven Kleinman, senior medical advisor at AABB, an association for professionals in the fields of transfusion medicine and cellular therapy. “We couldn’t wait."
Winter travel could bring more Zika exposure
Nationally, about 12 million red blood cell units were collected in 2013; plasma and platelet donations added 2 million more, according to the latest figures from the U.S. Department of Health and Human Services. To what extent donations outside Southern states will be tested is not known, but domestic travel patterns suggest testing will need to expand.
New York, for example, is out of the breeding range of the mosquito species that carry the virus, but snowbirds eager to leave winter weather for South Florida may well be exposed to Zika. The Greater Miami Convention & Visitors Bureau said more than 2 million New Yorkers traveled there in 2015. And if a mosquito doesn’t infect a visitor, Zika can be spread through sexual contact.
“Over the winter, there may be more impact on the blood supply,” AABB’s Kleinman said, as travelers are asked to defer. The Blood Center of New York, for example, is studying whether to add blood testing to its Zika-screening effort because of the popularity of winter travel.
Despite the dent in donations, hospitals aren’t reporting an impact yet. John Wilgis, director of emergency management services at the Florida Hospital Association, said the organization hasn’t received any reports of shortages. The association is monitoring events and asking members for updates, but Wilgis said “it’s business as usual” during a time of “a slow-moving threat.”
That view is shared at the South Florida Hospital and Healthcare Association. Jaime Caldwell, president, credited OneBlood for “staying on top of the issue. We’re not seeing shortages.”
But hospitals “don’t know what we do to get it to them,” America’s Blood Centers’ Katz pointed out.
“It is very gratifying for them to say that they see no impact,” he said, adding, “the blood community is like a duck – calm above the surface, but paddling like hell underneath.”