At-home rapid COVID-19 tests detect almost as many infections as lab tests, study finds

.Rapid COVID-19 antigen tests are nearly as accurate as laboratory tests at detecting infections when used twice a week, a new study suggests.

Researchers found that the quick at-home test was able to detect all 15 cases of Covid and 96 percent of samples within three days of infection   

Antigen tests look for proteins found on the surface of the virus compared to the virus's genetic genetic material, which is what lab tests detect. 

Traditionally, lab tests have been considered more precise at detecting Covid cases. 

However, samples often take two to three days to return results whereas rapid antigen tests often return results in just 15 minutes.

The team - made up of researchers from Harvard TH Chan School of Public Health and Mount Sinai School of Medicine - says the cheaper, simpler test can be used as part of screening programs at workplaces, schools and other settings.

A new study found that, when used twice a week, rapid Covid tests (above) correctly identified 15 out of 15 cases of Covid and detected 96% of cases with three days of symptoms appearing

A new study found that, when used twice a week, rapid Covid tests (above) correctly identified 15 out of 15 cases of Covid and detected 96% of cases with three days of symptoms appearing

Laboratory tests, also known as polymerase chain reaction (PCR) tests, are considered the gold standard in COVID-19 testing.

They are considered to be highly accurate because they detect genetic material of the coronavirus in a patient's mucus or saliva.

However, they are costly and have long turnaround time because the sample needs to be submitted to a lab and analyzed by a professional.

Results generally take at least two days to be returned, making it hard for PCR tests to be used for widespread surveillance.

Meanwhile, rapid tests look for antigens, or proteins found on the surface of the coronavirus.This screening method is faster, with results returning in 15 minutes, but less precise with patients more likely to have false negatives - receiving a negative result even though they're actually infected.

[However, past modeling studies have shown that, when antigen tests are used frequently, that repeated use will catch the majority of Covid cases in a community.]

For the new study, published in JAMA Network Open, the team compared PCR tests to Direct Antigen Rapid Tests (DART) made by Cambridge, Massachusetts-based biotech firm E25Bio.

Researchers has 257 individuals self-swab at home using DART twice a week for six months and then compared the results to those from PCR tests.  

Overall, DART was able to detect 15 out of 15 cases. 

When used within three days of symptoms appearing, DART correctly identified 26 out 27 samples for a sensitivity rate of 96.3 percent.

'Detection on day three is almost as effective as detection on day one for reducing the incidence of COVID-19, if 75 percent of a population is surveilled,' the authors wrote.

What's more, for one participant, DART detected COVID-19 infection one day before the PCR test. 

'Use of twice-weekly DART testing allowed the activities of the coworking sites to continue safely during the pandemic,' the researchers continued.

'Most of the positive participants reported that they did not recognize symptoms of COVID-19 until they received a positive result.  

'Frequent at-home testing with DART allows infected individuals to be identified and quarantined immediately. Such surveillance can prevent viral transmission in in-person work environments or other social settings.'

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