Posted on August 29, 2016 at 2:18 AM
by Craig Klugman, Ph.D.
The FDA has announced that within the next 3 months, all donated blood in the United States should be screened for Zika virus. Puerto Rico and Florida are already conducting such screening. In the next four weeks, 11 more states should be screening (Alabama, Arizona, California, Georgia, Hawaii, Louisiana, Mississippi, New Mexico, New York, South Carolina and Texas) followed by nationwide testing within the next 3 months. The goal is to have a safe and trusted blood supply.
Although on this surface this looks like a preventive public health move, it is a political one. Consider that there have been 8,000 documented cases of Zika in the U.S. with only 2,000 of them locally acquired (meaning no history of travel to a country with Zika). Most of the local cases are in Puerto Rico. Eighty percent of those infected never have symptoms.
The emphasis seems to be more on trust than it is on safety. Only 1/3 of the 15 countries that reported confirmed infections have reported transmission through sexual contact. This could mean either that other countries aren’t aware or aren’t reporting, or that such transmission is only happening among certain strains of the virus. The FDA announcement, however, is aimed at protecting the blood supply. And data for blood transmission is also lacking, whether a lack of awareness or reporting. In fact, according to the CDC, Brazil is the only country that has seen any Zika in its blood supply. During the original French Polynesian outbreak, 2.8% of blood donors tested positive. Whether people were infected through transfusions has not been reported.
The CDC theorizes that Zika can be spread via blood: “There is a strong possibility that Zika virus can be spread through blood transfusions. Because most people infected with the Zika virus don’t show any symptoms, blood donors may not know they have been infected. There have been cases of Zika transmission through blood transfusion in Brazil.”
The begged question is, “Is there a problem or potential problem with Zika in the blood supply or is testing a solution to fear?” Consider that the main tests used to detect Zika have not yet been FDA approved. Nine tests have received emergency approval but their accuracy and rates of false negatives and positives are not known. An emergency approval means “Under section 564 of the Federal Food, Drug, and Cosmetic Act (FD&C Act), the FDA Commissioner may allow unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or prevent serious or life-threatening diseases or conditions caused by CBRN threat agents when there are no adequate, approved, and available alternatives.” Emergency approval is not the same as approved and proven.
The tests vary in price with some costing as much as $500 per test. The CDC has made test kits available at no cost to some groups, but the funding for Zika work is running out and Congress has not approved more. Though it’s difficult to put a price on such things, there is a question of from where the funding to pay for this screening will come.
For anyone who lived through the 80s, the emergence of Zika may sound similar to the appearance of HIV. In that epidemic, even though the first cases emerged in 1981 and the first blood transfusion case was reported in 1982, the FDA did not recommend testing all donated blood until 1987, two years after approving an HIV detection test. Over 14,000 people have acquired HIV through transfused blood (most before the 1985 test was available). Is the FDA trying to avoid a repeat of not acting until after people were harmed?
The analogy is imperfect between HIV and Zika. HIV is the cause of AIDS which was a fatal disease in the days before modern therapies. In the U.S., HIV was found in men-who-have-sex-with-men, IV drug users, prostitutes, and people who received infected blood from a transfusion. The disease was also associated with people from Haiti, where the infection rates were high. Such groups were highly stigmatized to begin with (gay, poor, immigrant, sex workers, etc.) which may have led to slower action. If people answered honestly, then screening questionnaires given before one donated blood could be effective in weeding out inflected blood donations. In fact, even today, many of these populations are still restricted from donating blood. Infection was associated with stigmatized behavior meaning that many believed personal responsibility was in question, another reason that reaction was slow.
However, Zika is random since mosquitoes do not discriminate based on age, sexual orientation, country of origin, or stigmatized behavior. Also, the main victims of Zika are the most vulnerable and the cutest of all humans—newborns. Aesthetically, the babies with small heads evoke our pity since we are supposed to protect children. Grown men with AIDS and its associated (and often visible) diseases did not evoke the same reaction of empathy with the public. Aesthetics often dictate what we view as ethical.
The analogy also does not hold because HIV killed. Zika causes brain deformities in babies and perhaps Guillain-Barré syndrome in a very small percent of infected adults (though the causal effect has not been established). To protect cute little babies, the U.S. has moved quickly even before there is a problem.
Of course, some might say that nationwide testing should begin immediately because of the lessons learned from HIV. Zika has been reported in more states than those on the first wave list. The FDA should be applauded for these efforts: Stopping a potential means of transmission before it starts. If this is the goal, and Zika can be transmitted through the blood, then why have we not begun programs to protect other potentially at-risk populations like IV drug users and prostitutes? After all, during the last blood-borne epidemic, these were at-risk groups. And since sex is a means of transmission, then safe sex education and condom distribution at all age levels would seem to be important. Simple programs like needle exchange and condom distribution are inexpensive and would help protect these populations. Perhaps the reason is that like with HIV, the vulnerability to infection from these groups is based on behavior—drugs and sex—that are already stigmatized. Testing blood is an easy political and social sell, but giving out needles, educating people about safe sex, and giving out condoms might be seen as condoning such behavior. If our goal is truly to protect lives form potential biological threats, then more efforts are needed.
Given the cost of testing, perhaps not all blood needs to be tested, but just blood that is likely to reach vulnerable populations, pregnant women, couples trying to become pregnant and infants. After all, most people never have symptoms and have no effects from the virus. The CDC has stated that questionnaires alone are an inadequate screen because infection is not associated with behavior. Whereas everyone was at risk of death from HIV and AIDS, only a segment of the population is at risk of severe problems from Zika. If only some blood was tested (to save costs), perhaps certified Zika-free blood could be labeled and made available for at-risk populations.
My final concern about this FDA move is its effect on our behavior toward each other. With HIV, the FDA banned whole categories of people from donating. The result of this stigmatization was discrimination and fear against groups of people such as gays, Haitians, and IV drug users. Using this as an analogy, might this ban ignite discrimination against people from Latin, South America and the Caribbean? Or is the non-behavioral aspect superseding such possibilities?
On the one hand, testing blood for Zika should be applauded for trying to protect the population before blood-to-blood transmission appears. On the other hand, the tests have not been rigorously evaluated and approved through normal FDA channels, and there have been few reported cases. If the FDA is trying to learn from the past, then that is laudable. This is a political one since it is the least controversial. Acting to protect drug users, sex workers, and sexually active adults requires steps that are not politically popular. But if Zika is blood-born, then there is a moral obligation to take these hard steps to protect everyone, not just the cute.