CDC Declines to Validate High-Volume Measles Test; Four States Urge Reconsideration

The US Centers for Disease Control and Prevention has declined to validate a new high-volume measles testing method, citing “other competing priorities”, according to state health officials. Health officials from four states have now urged the agency to reconsider.

California and Washington asked the CDC in May to validate a new way to test for measles, but after waiting two months, the CDC denied the request. The information appears in a letter from the West Coast Health Alliance to the CDC director, Erica Schwartz.

The letter, signed by health officials in California, Hawaii, Oregon and Washington, asks Schwartz to reconsider and validate a rapid, high-volume measles test in preparation for major outbreaks.

The alliance also asked the CDC to create protocols to test for other high-priority pathogens to prepare for future outbreaks. Such a test, the officials said, would “dramatically strengthen” the ability of laboratories to respond quickly, helping preparedness for known pathogens like Ebola or hantavirus as well as emerging threats.

Emily Hilliard, a spokesperson for the US Department of Health and Human Services, said the CDC is “ensuring state and local health departments have the support needed to strengthen measles detection and outbreak response” and that the agency was “prioritizing emerging technologies”.

The spokesperson did not answer questions about whether the CDC had plans to validate a high-throughput measles test, or assay, leaving the agency’s position on the states’ central request unclear.

Right now, laboratories have to rely on lower-volume tests for measles, like individual polymerase chain reaction (PCR) tests. During the Covid pandemic, most public health labs bought high-volume equipment, like the Hologic Panther Fusion, a PCR platform that can process up to 500 tests in eight hours.

But there is no high-throughput test to diagnose measles that has been validated by the CDC. Texas state laboratories developed such a test during the measles outbreak in west Texas last year, but they have not distributed or published the protocol.

ARUP Laboratories, a national, academic, non-profit reference laboratory, published their assay for measles in the Journal of Clinical Microbiology in December. The CDC could validate this or another protocol so other public health labs could run diagnostic tests.

Benjamin Bradley, an assistant professor of pathology at the University of Utah and medical director of virology at ARUP, said high-throughput tests can process a lot of samples at once, and the automated instruments can also be faster and easier than manually conducting tests, offering more flexibility.

That is especially important in a fast-moving outbreak, Bradley said. One measles patient can infect 12 to 18 other unvaccinated people, and the virus can linger in the air for two hours. Quicker tests help identify and isolate positive patients, speed up contact tracing, and allow vaccines to be offered promptly to exposed people — vaccines taken within 72 hours of exposure can prevent infection.

There are no commercially available tests for measles; the current tests are developed by laboratories. Validating and publishing the process is crucial, Bradley said, because laboratories otherwise have to do the burdensome scientific work themselves, and shared protocols help labs.

The west coast officials said in the letter that the CDC has reportedly completed studies on the assays from Texas and ARUP Laboratories, “but they were not full validations or a comprehensive comparison”. They asked Schwartz to develop an assay for measles diagnostic testing on the Panther Fusion and publish the protocol, warning: “If a large outbreak were to occur in our region, without high-throughput capacity, it would be more difficult to scale up diagnostic testing appropriately, impairing patient care and public health investigation.”