The U.S. FDA moved the goal posts for other companies with its expansion of the emergency use authorization for Helix Opco LLC’s COVID-19 test to include both unsupervised self-collection of samples and testing of asymptomatic individuals. The new indications promise to make the Helix test the preferred tool for schools, universities, and work settings by reducing costs and increasing flexibility.
“This expansion of our EUA to enable on-site unsupervised self-collection helps our government, education, and employer partners significantly streamline their operations, decrease their collection costs, and more rapidly expand access to COVID-19 testing,” said Helix CEO Marc Stapley.
The Helix real-time RT-PCR test uses self-administered midnasal swab collection with samples sent overnight to the company for processing.
Without the need for a health care professional to oversee testing, organizations have more options for when, where and how they set up testing. Unsupervised testing could help groups trying to track population-level spread of the SARS-CoV-2 virus in the rural areas with few health care workers currently seeing an explosive rise in cases.
Employers and schools focused on quickly identifying cases to limit spread so they can reopen or remain open will also benefit from elimination of the supervision requirement and the ability to test asymptomatic individuals. Despite well-established community spread across much of the U.S., most real-time RT-PCR tests remain restricted to individuals with symptoms or known exposure to someone with COVID-19. That’s of limited use when about half of COVID-19 transmissions in the U.S. come from people who are asymptomatic or presymptomatic, according to the CDC. Worse, recent research indicates that individuals are most contagious in the two days before symptom onset and one day after symptoms first appear.
“Being able to broadly test individuals irrespective of symptoms is critical to ensure we’re able to prevent and mitigate outbreaks and identify people as early as possible in the course of infection,” said James Lu, co-founder and president of San Mateo, Calif.-based Helix. “Further, reducing the barriers to testing enables us to reach some of the most vulnerable and underserved populations in the U.S.”
But is it accurate?
Many organizations eager to implement frequent testing have turned to less expensive and faster processing antigen tests that detect the presence of viral proteins from either nasal swabs or saliva samples. While they may work well enough for population-level studies, the false-negative rate – as high as 50% in some cases – make them less useful for limiting spread of the coronavirus in situations with high degrees of interaction or close quarters as seen on factory floors or dormitories.
RT-PCR tests like the one Helix provides are considered the “gold standard” for infection detection. As caseloads climbed this summer, however, many experts and anxious patients decried the time required to obtain results, which took up to two weeks in some locations and made the results largely useless for contact tracing and other critical steps for controlling spread. Helix processes samples in its CLIA-certified, CAP-accredited high complexity laboratory and has been able to turn around results in 14 hours from sample receipt since it received the initial EUA for the test in July.
Two other concerns could limit adoption of the Helix test. Both unsupervised collection and the use of midnasal as opposed to nasopharyngeal samples have raised questions about reduced accuracy in PCR tests. A research study published in JAMA Network Open in July may have put some of those concerns to rest, at least for symptomatic patients.
Researchers at the University of Washington compared results from midnasal, self-administered swabs to nasopharyngeal swabs by health care workers. In a study of 185 people, the team found that “Unsupervised home midnasal swab collection was comparable to clinician-collected nasopharyngeal swab collection for detection of SARS-CoV-2 in symptomatic patients, particularly those with higher viral loads.” Overall, the home swabs had an 80% sensitivity and 97.9% specificity compared to the clinician swabs. False negatives occurred most often in samples with low initial viral loads and occurred at a median of six days after symptom onset compared to four days for true positive tests.
Evaluation of the Helix test appears to demonstrate that the company has overcome this final challenge, getting reliable results in asymptomatic individuals.
“Testing asymptomatic individuals is an important part of any strategy to reopen schools, workplaces, and communities safely – but this requires a highly sensitive and highly specific test to accurately identify asymptomatic individuals,” Lu told Bioworld. “This lowers the risk of both false negatives and false positives, which can be equally disruptive. The FDA’s authorization of our test for this purpose demonstrates that our test meets these requirements to accomplish this strategy.”
Helix’s clinical performance studies demonstrated the test had sensitivity of 100% (95% CI: 89.9%-100%) and specificity of 100% (95% CI: 93.1%-100%).
Lu said that, with support from the National Institute of Health’s RADx program, the company is close to reaching its capacity target of producing 100,000 tests daily.