The U.S. Food and Drug Administration has given its first nod to a molecular test developed by Abbott Laboratories for the Zika virus for use to test whole blood. This expands upon an existing use of the test from the Abbott Park, Ill., company; it had already received emergency use authorization for use to test serum, plasma and urine.

The whole blood test is expected to enable diagnoses over a longer period of time, up to two months after symptom onset, rather than about a week. That's important since the symptoms of Zika virus are often mild or even nonexistent, making it somewhat improbable that patients will be tested within the first week or two after infection when serum or urine tests are effective.

LONGER-LASTING RELEVANCE

"There are a couple of reports in the literature of whole blood detection lasting longer, up to two months and at higher levels. This is in contrast to serum or plasma, which are effective for the first week after symptoms begin. This could be a big advantage in terms of identifying people who could be contagious," George Schneider, director of assay development at Abbott's Diagnostics business, told Medical Device Daily.

The Abbott Zika molecular test for a serum, plasma, urine or whole blood sample is based on viral RNA detection, but serology-based tests can confuse a long-ago infection with a tropical disease, such as dengue or chikungunya, for a Zika viral infection.

Specifically, the FDA has authorized the Abbott Realtime Zika test to detect the Zika virus in whole blood under the emergency use authorization. It is requiring that a whole blood sample be collected alongside a serum or plasma sample, as well. The Abbott Zika test runs on the company's m2000 Realtime System. It provides Zika test results within five to seven hours.

According to guidelines from the Centers from Disease Control (CDC), serum and urine tests are expected to be effective within two weeks of infection; thus far, these remain the primary diagnostic specimens tested, particularly in non-pregnant patients.

"The one test can use those four sample types. What's used depends on the availability of the specimens; the preferred specimens are serum and urine. That's a conservative stance from the CDC's standpoint, but I think it's going to become more of an advantage for whole blood because of the longer ability to detect," said Schneider.

"There are different tests authorized to use the different sub-sets of samples. But I think we are the only ones with all four specimen types," he added.

WHAT'S NEXT IN ZIKA DX?

Abbott is continuing its Zika research and development on at least a couple of fronts: to develop a point-of-care diagnostic and, separately, to create a serology-based test that does not produce false Zika positives based on exposure to other tropical diseases.

The Zika test from Abbott, regardless of the sample type used, is laboratory-based. This requires a certain level of infrastructure, including reliable power, which may not be available in remote areas.

The development of a mobile platform to test for Zika, as well as multiple other tropical pathogens, is being backed by the U.S. Defense Advanced Research Projects Agency (DARPA) via a contract with Abbott. The pair is working on a Zika test as part of their ongoing Mobile Analysis Platform (MAP) development.

"The more people who know their status, hopefully they will take the kind of precautions they can to reduce the rate of transmission. By including this specimen type [whole blood] that has the advantage to detect the virus for longer periods of time, we can further that effort," summed up Schneider. The virus is sexually transmitted, as well as passed from pregnant mother to fetus, but patient efforts can help to disrupt that cycle.

There are an estimated 4,800 people infected with Zika in the U.S., with an additional roughly 35,000 in the U.S. territories – primarily in Puerto Rico. The coming summer will revive the conditions that favor mosquitoes, which transmit the Zika virus.

KEEPING PACE IN CRM

Separately, earlier this week Abbott made good on a priority for its St. Jude Medical acquisition, which closed early last month. The company reported FDA approval for St. Jude's magnetic resonance imaging conditional labeling for both its Assurity MRI pacemaker and Tendril MRI lead. St. Jude's fourth quarter sales, particularly in Cardiac Rhythm Management, weren't as strong as Wall Street had expected.

This was, in part, due to a slower-than-anticipated FDA nod for the Assurity pacemaker and Tendril. St. Jude had expected to have the approval in hand during the fourth quarter of 2016.

"We estimate that St. Jude's CRM business was weaker than expected, attributed to the absence of the MRI-safe devices (both high and low voltage) and the recent ICD (implantable cardioverter defibrillator) battery depletion warning," summed up Wells Fargo senior analyst Larry Biegelsen.

He anticipated that the new FDA approval will help Abbott's "pacemaker business to improve and recapture share in the U.S. low voltage market. For reference, we estimate that Boston Scientific's U.S. pacemaker business has grown 20 percent+ each quarter post-MRI approval."

Biegelsen said the approval also makes him more confident in an FDA nod for an MRI-compatible version of Abbott's high voltage cardiac device. That's anticipated in the fourth quarter, after being pushed out from the second quarter.