Is There a Test for Delta and Other COVID-19 Variants?

For a little while in the early summer of 2021, it looked like we were finally beating the COVID-19 pandemic. And then the Delta variant showed up. The highly transmissible variant quickly became not only the dominant variant in the U.S. but almost the only variant in the country. So, is there a test to detect COVID-19 variants that anyone can have access to? It's actually a little more complicated than most people think.

What Is the Delta Variant?

Delta went from causing just 2% of COVID-19 cases in mid-May 2021 to 98% of cases by mid-August 2021, according to data from the Centers for Disease Control and Prevention (CDC).

The variant—aka B.1.617.2—was originally detected in India in December 2020. It's a mutation of B.1.617, the so-called "double mutant" strain that made headlines back in April 2021.

The Delta variant had several mutations on the spike protein of SARS-CoV-2, which helped it spread more easily than the original SARS-CoV-2. The CDC specifically said that this variant was more easily spread and posed a "potential reduction" in the effectiveness of the COVID-19 vaccine. They also initially thought it may make some monoclonal antibody treatments less effective against the virus, but fortunately, that wasn't the case.

Since the Delta variant made up 98% of COVID-19 cases in the US in August 2021, if you had COVID-19 during that time, you got it from the Delta variant, William Schaffner, MD, an infectious disease specialist, and professor at the Vanderbilt University School of Medicine told Health.

Testing for Variants

This is where things get a little tricky. Technically, there is a test to differentiate between the different variants—but it isn't something you or your doctor have access to. "There is no commercial test for the Delta variant," Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security, told Health. Instead, what happens is that a "selected sample" of positive polymerase chain reaction (PCR) tests are "further studied to look for the characteristic mutations" of the variant," Dr. Adalja explained.

The CDC has a national SARS-CoV-2 genomic surveillance program that works to ID and tracks down variants of the virus that are circulating in the US. Under this program, they regularly receive samples from state health departments and other public health agencies for genetic sequencing, further characterization, and evaluation. The system processes up to 750 samples a week and then calculates a slew of information, including what percentage of cases are due to certain variants.

"This sequencing is only done at specialty labs," Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo in New York, told Health.

Basically, there's a small chance that your positive COVID-19 test could be sent off to the CDC for genomic sequencing, but you wouldn't know or find out about it anyway.

Specific Variant Testing

"At the end of the day, it doesn't matter," Dr. Russo said. "Whether you're infected with the Delta variant or another one, it's not going to affect how you manage the illness."

Dr. Schaffner agreed. "We don't have the capacity to test everyone for the Delta variant now, and we don't need to," said Dr. Schaffner.

Ultimately, knowing which positive COVID-19 tests were from the Delta variant was for public health surveillance and tracking, Dr. Russo said. "It's important from a public health point of view, but from a personal point of view…there's no significant reason that you need to know which variant you have," said Dr. Russo.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.