Sensitive Test Takes Only 10 Minutes To Detect Coronavirus Infection

Health experts believe that mass testing for COVID-19 could play a very important role in the fight against the disease. Identifying people that recovered from the disease may guide efforts to isolate at-risk communities and allow the reopening of areas with lower risk of transmissions. 

There are now more than 3.7 million cases of COVID-19 worldwide. To help public health officials determine the actual number of people infected, researchers have developed a new "sensitive" tool that works like a pregnancy test to find traces of the disease in the blood. 

“Because COVID-19 symptoms range from mild to severe, with some people apparently having no symptoms, the number of people who have been infected with the SARS-CoV-2 virus at some point is likely much higher than the number of confirmed cases,” the American Chemical Society said in a press release. “As U.S. states begin to ease lockdown restrictions, widespread testing of the general population will be important to identify people at early stages of disease, or people who lack symptoms but can still infect others.” 

The tool, described in the journal Analytical Chemistry, looks for antibodies left in the blood after the immune system fought the novel coronavirus. Researchers said it could also help confirm infection in people who tested negative by other methods but showed symptoms of COVID-19.

Researchers developed the antibody test based on the technique called a lateral flow immunoassay (LFA), which is also used for home pregnancy test. To trace COVID-19, the team added a viral coat protein to a strip of nitrocellulose and added blood samples. 

As the sample flows from one end of the strip to the other, the antibodies against the coronavirus should stay on the part that contains the viral protein. A fluorescent like glow appears if antibodies are present. 

Researchers said using fluorescence makes the blood test more sensitive than some other LFAs, like pregnancy tests, which leads to faster results. The team tested the new COVID-19 detecting tool with infected people and those who tested negative for the disease.

Results showed the fluorescence-based blood test correctly diagnosed all samples as positive and confirmed a "negative" case that showed symptoms of the coronavirus disease. The process took only 10 minutes per sample to deliver results. 

“We expect this assay to be highly useful for helping to contain the COVID-19 outbreak by allowing timely diagnosis through early detection of [the novel coronavirus],” researchers said in the study. 

Doctors may also use the blood test to identify recovered people with high levels of antibodies, which could make them possible donors of plasma for patients still fighting COVID-19.

COVID-19 Antibody Test A new lateral flow immunoassay can detect antibodies against SARS-CoV-2, which appear as a bright orange line when placed on a fluorescence reader (right). Guanfeng Lin/American Chemical Society