This story was last updated September 2 at 5:19 p.m.

Local officials and medical experts have repeatedly touted reliable rapid antigen testing as a vital tool in slowing the spread of the coronavirus in our region and nationwide.

But the availability of rapid coronavirus antigen testing — particularly for those who are asymptomatic — remains limited in the D.C. area.

DCist/WAMU has reached out to a number of urgent care clinics, and medical facilities. Many either don’t have rapid testing or provide it only if patients meet strict criteria. The facilities cited either a lack of availability of supplies needed for the tests, and concerns over the performance of the rapid tests.

However, medical experts – like Dr. Monica Lypson of George Washington University – believe that rapid antigen testing should also be available for those who may be asymptomatic. In July, the Centers for Disease Control and Prevention estimated that as high as 40% of those who are infected with COVID-19 are asymptomatic.

“Rapid testing can become a critical tool… to continue to manage community spread, particularly as a screening tool,” says Lypson. “But it’s just not ubiquitous in our environment quite yet.”

The rapid antigen tests are generally considered to be less sensitive and less accurate than the PCR tests, which the CDC calls the “golden standard.”

Four rapid antigen tests are currently approved for use by the FDA under an emergency authorization, including one from Abbott Labs that just got approved last week.

Antigen tests, which can also be used for other respiratory viruses, look for specific proteins on the surface of the virus which will lead to the production of antibodies. They are done via nasal or throat swab. However, as the CDC cautions, they are most accurate when viral load is the highest, which often means in the early stages of an infection. A negative result doesn’t guarantee that the patient doesn’t have the coronavirus, only that those markers aren’t being detected.

Due to this, accuracy of these tests remains a debated topic. The CDC recently updated its guidance for the use of antigen tests, writing that the specificity (the ability to detect a negative case correctly) of the rapid antigen tests is “generally as high” as PCR tests and that “false positive results are unlikely.”

But according to Science Magazine, the test’s accuracy could be as low as 50% – meaning half of infected people could incorrectly be told they don’t have COVID-19.

However, experts believe that there is still immense value in deploying rapid tests. They can provide results in as little as 15 minutes, allowing for more frequent testing that can provide a wider picture of infections. They can be cheaper than PCR tests, less time-intensive, and can provide results at the testing site. If a rapid test is cheap enough and fast enough, it can be run multiple times ensuring that one false result can become part of a larger data set as opposed to a singular data point — making any outliers more clear. It’s thought that this what happened with the Washington Nationals’ Juan Soto when he received one positive COVID-19test result and a number of negatives in July.

Rapid tests are also invaluable tools for testing in congregate settings where the detection of an infection in its early stage can prevent a facility-wide breakout.

Some issues and delays remain in getting PCR test results back in a timely manner, as was the case earlier in the summer.

Lypson of George Washington University says when we start talking about going back to school or work in-person, rapid testing can be a good initial step in an overall testing strategy.

“The sensitivity of the [antigen] test is not as good as PCR, but if you’re using it for screening in a population that has low community spread, it is a good tool,” says Lypson. “I think we feel comfortable in medicine using tests that don’t have a 95% to 99% sensitivity as the PCR when we know we’re using it for screening protocols.”

To this end, local jurisdictions are working to secure as many rapid antigen tests as possible. In early August, Maryland and Virginia joined other states in an agreement to purchase a half million rapid antigen tests per state with the assistance of the Rockefeller Foundation. “With severe shortages and delays in testing and the federal administration attempting to cut funding for testing, the states are banding together to acquire millions of faster tests to help save lives and slow the spread of COVID-19,” Maryland Gov. Larry Hogan said in a press release announcing the agreement.

As of publication of this story, however, those rapid tests have not yet been purchased, much less deployed. “Virginia is still a few weeks away from purchasing, receiving, and activating those 500,000 rapid tests,” a spokesperson for the Virginia Department of Health wrote to DCist/WAMU in an email.

The Maryland Health Department confirmed a similar circumstance. “The state has not yet purchased [point-of-care] tests yet, but is working with the Rockefeller Foundation on a procurement process to acquire the point-of-care tests,” wrote a spokesperson. The spokesperson also said no state-supported testing sites are currently utilizing rapid tests, though a number of private providers are.

A review of Maryland testing sites reveals that the handful that are offering rapid testing are doing it “only when symptoms present.”

D.C. does offer rapid testing (specifically Abbott ID Now), but not to the general public. Currently, the city is only providing tests to vulnerable populations and congregate settings like homeless shelters, jails, long-term care facilities, and public hospitals, a spokesperson for D.C.’s Department of Forensic Sciences confirms.

They also have a mobile testing unit with rapid antigen tests that can test up to 50 people every four hours for “vulnerable populations,” those who have limited mobility or other conditions that would make it hard for them to access the public sites, according to the spokesperson.

D.C.’s community testing sites, like those in firehouses, Anacostia, and Judiciary Square, are all PCR tests and are being conducted by LabCorp.

There are no plans to provide rapid testing to the general public, says D.C.’s Department of Forensic Sciences.

Only a few private providers are offering rapid tests at all, with DCist/WAMU finding only one making it available to those who do not meet a strict criteria and are asymptomatic.

MedStar has more than a dozen clinics and hospitals across the region in D.C., Maryland, and Virginia. Nearly all of these locations do offer rapid antigen testing, but only to those who met “testing criteria” due to a supply “national shortage.” MedStar has not provided information about the testing criteria, and if it plans on expanding availability of rapid antigen tests as of publication time.

Both Children’s National Hospital in D.C. and Patient First (a chain of urgent cares with several locations in the region) are not providing rapid testing nor have any plans of using them. They both cite performance-related issues in correspondence with DCist/WAMU.

Inova hospitals, which has six hospitals in Northern Virginia, only provides rapid testing in emergency situations but also has not yet clarified what an example of that would be. Virginia Hospital Center was providing rapid testing to confirm previous COVID-19 diagnoses for inpatients and staff in April, but hasn’t confirmed if they have continued this.

George Washington Medical Faculty Associations (at which Lypson is a physician), with three immediate and primary facilities in D.C., are currently only using PCR tests but are “evaluating the market” and considering adding rapid antigen tests.

Urgent Care of Arlington, a privately-owned urgent care, is the only one offering rapid antigen testing to anyone who makes an appointment. Using Quidel (one of the four currently approved by the FDA), the urgent care says that these tests are “almost as accurate as the PCR tests.” Quidel says its tests have a 96.7% accuracy rate.

Lypson says it’s true that testing resources have been limited and that rapid antigen tests are not as accurate as PCR tests, but in order to the slow the spread of the virus, we need every tool available.

“We still don’t have good community control of the spread of the virus,” says Lypson. “Rapid testing [is] a critical tool because it allows you more flexibility in terms of screening and implementing changes.”

This story has been update with further clarification about D.C.’s mobile testing units.