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Can COVID tests detect the rapidly spreading Delta variant?

June 30, 2021, 8:00 PM UTC

The Delta variant is wreaking havoc across the globe. The highly transmissible and rapidly spreading coronavirus mutation (which may in turn be creating even more variants) is battering Europe and India and contributing to a growing share of new COVID cases in the U.S.

Tackling COVID has always necessitated a multipronged strategy involving coronavirus testing, contact tracing, distancing, and masking procedures, and ultimately an unprecedented vaccination campaign. On the immunization front, initial evidence suggests that Pfizer’s, AstraZeneca’s, and Moderna’s COVID vaccines are all remarkably effective in preventing serious illness, hospitalization, and death among patients who contract the Delta variant. Moderna’s shot has even shown promise in producing antibodies that protect against this strain. But can the actual COVID tests on the market detect the Delta variant?

To put it simply: not always. While the Delta variant (otherwise known as B.1.617.2) may be the pathogenic offspring of the novel coronavirus, it carries distinctive biological markers that some among the dozens of commercially available COVID tests from academic institutes and medical giants may not be able to sense.

Testing for the Delta variant usually has to be done on a more precise level involving polymerase chain reaction (PCR) testing platforms, which tend to be more accurate and sensitive to genetic variations within the coronavirus. But that level of testing also takes more time than a rapid response test which may return results within a half-hour but miss out on some of the biological details. Those faster diagnostics may be able to sense whether or not you’re generally infected with COVID, but not necessarily whether it’s the Delta strain specifically that’s afflicting you.

For instance, in South Carolina, Delta variants aren’t regularly screened for by the state’s public health department. That means that just a handful of Delta-variant linked cases have been specifically identified even though the true number is likely much higher given how quickly this strain is spreading in the U.S., particularly in the South and the Midwest.

An initial COVID test would then have to receive additional screening that involves more intricate genomic sequencing of a patient’s sample in order to home in on whether or not it’s a Delta variant case, and that process is reliant on a mishmash of private, state, and federal laboratories that are carrying out the screening, according to South Carolina’s public health department.

In the meantime, companies are already going to work on creating rapid tests which can detect the Delta variant without requiring all the bells and whistles of an intensive PCR test. One firm, Avacta, says its own antigen test can detect the variant. In the U.K., which has been hit hard by the Delta variant, more sophisticated PCR technology is being developed in order to keep tabs on the strain.

Regardless of whether a test can tell you if you have one COVID strain or another, the overall message from clinical studies is clear: Getting vaccinated is the best way to prevent serious illness and to protect others, no matter what new avatar the coronavirus takes.

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