FDA Provides Assistance for Regulatory Evaluation of Serological Tests to Detect Recent Zika Infection

Although prevalence of Zika virus continues to decline, researchers around the world have been channeling all of their efforts into promoting awareness of the virus and stressing preventive measures that individuals can take to protect themselves from infection.

One area of opportunity is in the realm of diagnostics—there is a need for diagnostic tests that are accessible, can be easily interpreted, and can effectively differentiate between Zika virus and other flaviviruses.

Luckily, more tools have been added to the arsenal, as the US Food and Drug Administration (FDA) report that they have made a panel of human plasma samples available to help diagnostic developers and public health officials evaluate serological tests designed to detect recent infection.

“At the onset of the Zika virus outbreak, when little was known about the disease or how to diagnose it, the FDA worked quickly with manufacturers to encourage the development of diagnostic tests and ensure they were available using its Emergency Use Authorization (EUA) authorities,” FDA Commissioner Scott Gottlieb, MD, commented in the official press release. “By providing manufacturers of these tests with standardized patient samples to use in properly validating these diagnostics, we will be able to better assess how well their test perform. This is part of our effort to ultimately bring these tests through the FDA’s formal review process to better ensure their reliability, and to enable broader access to Zika diagnostic testing.”

Currently, there are 2 diagnostic tests available: nucleic acid tests and serological tests. Nucleic acid tests are able to detect infection by confirming Zika RNA presence, while serological tests detect antibodies that are produced by an individual’s immune system when Zika virus is detected in the blood.

The FDA notes that serological tests “are especially important because there is often a small window when the virus’ genetic material is detectable.” Unfortunately, researchers have been having trouble creating this kind of test “because antibodies produced by the body to fight Zika virus are difficult to differentiate from antibodies produced to fight related viruses, such as dengue and West Nile virus.”

FDA officials hope that the sample panel—containing plasma samples from unidentified individuals infected with either Zika, West Nile or dengue virus—will help fill the gap. Diagnostic developers can use these samples to assess if the tests they are designing are capable of differentiating between Zika and the other 2 mosquito-borne viruses. Health officials will also be able to utilize this panel to compare the performance of the different diagnostic devices available under EUA.

“The FDA panel is available to developers who have interacted with the FDA through the pre-EUA process and have devices that are in the final stages of validation,” the announcement reads.