All blood donated in the United States and its territories should be tested for Zika virus, the US Food and Drug Administration recommended yesterday.
"There is still much uncertainty regarding the nature and extent of Zika virus transmission," said Peter Marks, director of the Food and Drug Administration's Center for Biologics Evaluation and Research. "At this time, the recommendation for testing the entire blood supply will help ensure that safe blood is available for all individuals who might need transfusion."
A previous FDA guideline issued in February that recommended active screening of donated blood only in "areas with active Zika virus transmission."
The agency's decision to expand blood screening in the United States was based on concerns about more cases of local transmission in Florida, the growing number of travel-related infections and concerns that Zika-tainted blood could unwittingly be given to a pregnant woman, putting her unborn baby at risk of severe birth defects.
"Over 8,000 travel associated and over 2,000 non-travel associated cases of Zika have been reported in the United States and US territories," Marks told reporters.
More than 2,500 people in the United States have been diagnosed with Zika, along with more than 9,000 in the US territories such as Puerto Rico, according to the US Centers for Disease Control and Prevention. Most of those cases were brought in by people who were infected while traveling abroad.
There are 584 pregnant women in the mainland United States with lab evidence of Zika infection, and 812 in the US territories.
Last month, Florida announced its first cases of locally transmitted Zika, with 42 infections.
"Testing of donated blood is already underway in Florida and Puerto Rico, as well as in other areas, and it has shown to be beneficial in identifying donations infected with Zika virus," said the FDA statement.
"About 1 percent of donations in Puerto Rico have tested positive for Zika virus," Marks said.
The expanded testing of the US blood supply "will be in effect until the risk of transfusion transmission of Zika virus is reduced," said the FDA.
FDA to roll out testing in stages
FDA's recommendations will roll out in stages. The recommendations will go into effect immediately in states and territoties with local, mosquito-borne transmission, affecting Florida and Puerto Rico.
In 11 states near areas with local transmission or high rates of travel-related infections, the guidelines must be implemented within four weeks. These states include Alabama, Arizona, California, Georgia, Hawaii, Louisiana, Mississippi, New Mexico, New York, South Carolina and Texas.
For the rest of country, the guidelines must be implemented within 12 weeks.
Marks said Hologic Inc and Roche Molecular Systems had been granted special approval for their tests to be used to screen the blood supply.
America’s Blood Centers is currently testing for Zika primarily in Florida, where local transmission has been reported. It has a network of 63 blood centres with 600 donation sites in 45 US states. It also has centers testing in areas of Texas that are considered at high risk for the spread of the virus, and an affiliate in Arizona testing high-risk donors.
Dr. Louis Katz, chief medical officer for America’s Blood Centers, said it would take a “titanic” effort to implement testing in the first-tier states expected to be online in four weeks, but stressed the organisation’s commitment to a safe blood supply.
“Testing labs and the test vendors are working feverishly to allow testing to start on time in the areas subject to the 12-week timeline,” he said in an email. “My conversations with the vendors suggest that if all goes smoothly that goal is feasible. Then, whether things go smoothly in an incredibly complex set of processes becomes critical.”
Zika is primarily spread by the bite of an Aedes aegypti mosquito, but it can also be transmitted sexually.
On Friday, US authorities announced the case of a man who passed on the virus to his female partner through unprotected sex. The man was unaware of his infection as he showed no symptoms.
Four out of five people who get Zika do not show any of the common symptoms, which may include fever, rash, joint pain and red eyes.
"As new scientific and epidemiological information regarding Zika virus has become available, it's clear that additional precautionary measures are necessary," said Luciana Borio, the FDA's acting chief scientist.
The World Health Organization says 53 countries around the world have reported Zika outbreaks since 2015.
Two US lawmakers, Congresswoman Rosa DeLauro of Connecticut and Congressman Lloyd Doggett of Texas, had recently urged the FDA to expand testing for Zika to blood banks nationwide, saying it would cost less than $10 per donor.
On Friday, DeLauro applauded to decision, calling it "a strong step forward in protecting our nation's blood supply and the American people."
(WION with inputs from agencies)