The early failure of the CDC’s very first COVID-19 test kits was due to contamination and a design flaw, agency scientists said on Wednesday. This is the CDC’s first public explanation for the high-profile misstep early in the US's troubled pandemic response, detailed recently in a BuzzFeed News investigation.
In February 2020, the CDC sent a first batch of COVID-19 test kits to public health labs nationwide, intended to aid in surveillance for the newly emerged coronavirus. Within days, most of the test kits failed to pass standard measures to verify that they worked, returning false positive results. The kits’ failure was an unwelcome surprise at that early moment in the pandemic. The debacle made headlines and embarrassed the storied public health agency for weeks, until states were allowed to run their own tests.
“It felt like we were driving blind, and we really were a little bit,” said Kelly Wroblewski, director of infectious disease programs at the Association of Public Health Laboratories, who was not involved in the report. Although the test kits’ verification failure certainly didn’t cause the initial spread of the coronavirus in the US, she added, “Those three weeks between when the initial test was rolled out and then failed and before we really had a new test available were a really, really long time.”
The new report on the test kit failure, in the journal PLOS One, a non-CDC publication, blames the false positives on contamination of the test’s “N1” component, and an unrealized design flaw in its “N3” component.
The findings follow a June 2020 summary report by the Department of Health and Human Services that blamed one CDC research lab for the problems, suggesting contamination in that lab caused the false positives in their components, rather than a design flaw.
The new study also follows last week’s BuzzFeed News investigation of the test kit failure featuring inadvertently released HHS interviews with lab personnel. The investigation uncovered emails suggesting that contamination from a manufacturing lab (not the research lab) might have instead caused the test kit problems, based on genetic evidence reported last year to HHS.
The PLOS One report agrees with the BuzzFeed News investigation that genetic evidence points to early test development materials at CDC as the source of contamination. But it also suggests there was a design flaw in the test, as well as contamination, a new suggestion that was dismissed in the early HHS investigation of the test kits. Like the 2020 HHS investigation, the study blames a research lab at CDC for the contamination. The BuzzFeed News investigation instead found that a “deep clean” of a manufacturing lab made that larger lab a leading suspect for the origin of the test kit contamination.
Because no genetic evidence of contamination turned up in assessments of the N3 part of the kit, the study results suggest that the N3 assay suffers from a design flaw that drives it to give false positive results in validation tests.
In response to a request for comment on the PLOS One study, a CDC public affairs representative replied with the statement: “Since the rollout of the initial COVID-19 test, CDC has implemented corrective measures and remains dedicated to the highest quality laboratory science and safety.” The study did not address why senior federal health officials relied on CDC labs to manufacture COVID-19 tests rather than engage with private test makers to produce them for the US.
Based on the study’s analysis, the new findings of contamination and a design flaw are plausible, University of Washington lab test expert Geoffrey Baird told BuzzFeed News by email. But the analysis doesn’t reveal exactly when the contamination was introduced, which we may never find out. “The issue of when (in what lab) the N1 contaminant got introduced is not really something that seems to be knowable based on chemical analyses,” Baird said.
For now, the N3 component of the CDC test remains on sale to testing firms; the CDC has not released any kind of warning about the suspect design flaw described in the study. An August 2020 report by CDC lab officials had simply said the N3 component had been pulled from its official test because analysis showed the test was equally effective without it, making it superfluous.
In retrospect, the problems with the CDC’s test kits are less surprising than they were at the beginning of the pandemic, Wroblewski said. Normally, diagnostic tests take months or years to design, validate, and manufacture. But, she said, it’s important to understand exactly how they failed in this case “for the sake of transparency, and perhaps restoring some faith in the agency.”