Technology

We checked three Covid tests at home. The results were mixed.

we-checked-three-covid-tests-at-home-the-results-were-mixed

Because of this, I don’t think home testing is as useful as some have hoped. If used on a large scale to screen for Covid, they could send millions of anxious people looking for laboratory tests and medical care that they don’t need.

Still relevant?

As the Covid-19 pandemic spread around the world last year, economists and scientists called for a massive expansion of testing and contact tracing in the United States to find and isolate infected people. However, according to the Covid Tracking Project, the number of daily tests in the US never significantly exceeded 2 million, and most of them were performed in laboratories or with specialized instruments.

Home tests are now in the tens of millions, their makers say, but some experts aren’t sure how important they will be at this point. “The real value of those tests was six months ago,” says Amitabh Chandra, a professor at Harvard University’s Kennedy School. “I think the move to over-the-counter products is great, but it has limited value in a world where vaccines are becoming more widely available.” Evidence of vaccinations might be more important than test results for travel and eating.

Companies that sell the tests say they are still a relevant strategy for getting back to normal, especially given the fact that children are yet to be vaccinated. For employers looking to keep an office or factory open, self-directed consumer testing could be a good option. An Abbott spokesperson told me that they could also help people “think about whether to coordinate more covid-conscious bridal showers, baby showers, or birthday parties.”

The UK government started giving away free Covid antigen tests in the mail and on street corners on April 9th. She wants people to “get into the habit” of testing themselves twice a week as social distancing restrictions are relaxed. In addition to vaccines, free testing is part of this nation’s plan to fight the virus. However, a leaked government memo later said health officials were privately concerned about a false alarm tsunami.

There is still no national campaign for home testing or subsidies for them in the US, and as an expense they are still too expensive for most people to use on any frequency. That may be the best in my experience.

Types of tests

The three tests we tried included two antigen tests, BinaxNow from Abbott Laboratories and a kit from Ellume, as well as a molecular test called Lucira. In general, molecular tests that detect the genes of the coronavirus are more reliable than antigen tests that determine the presence of the virus’s outer shell.

Everything you need is in one box, except in the case of the Ellume test, which has to be paired with an app. Overall, the Lucira test had the best combination of advertised accuracy and simplicity, but was also the most expensive at $ 55.

We haven’t tried Quidel QuickVue, any other antigen test, or any molecular test from Cue Health. While these tests are approved for home use, they are not yet sold directly to the public.

After trying all of the tests, I don’t intend to invest in using them regularly. I work from home and don’t socialize so I don’t really have to. Instead, I plan to keep at least one test in my closet so I can quickly find out if it’s Covid-19 if I feel sick or lose my sense of smell. The ability to test at home could become more important next winter when the cold and flu season returns.

ABBOTT LABS

BinaxNow from Abbott

Required time: about 20 minutes
Price: $ 23.99 for two
Availability: In some CVS branches from April. Abbott says tens of millions of BinaxNow tests are performed every month.
Accuracy: 84.6% for the detection of Covid-19 infections, 98.5% for the correct identification of Covid-19 negatives

This is the home version of the quick 15-minute test the White House used to screen employees and visitors last year. It’s an antigen test that examines a sample from a nasal swab to detect a protein in the virus’s envelope. It went on sale in the US last week and I was able to purchase a two-test kit from CVS for $ 23.99 plus tax.

The technology used is called “Lateral Flow Immunoassay”. In simple terms, it means that it works like a pregnancy test. It’s basically a paper card with a test strip on it. As the sample flows through it, it encounters antibodies attached to the virus protein and then to a colored marker. If the virus is present, a pink bar will appear on the strip.

I found the test to be pretty easy to perform. Using a pipette, put six drops of the chemical into a small hole in the card. Then insert a swab after passing it around in both nostrils. Rotate the swab counterclockwise, fold the card to bring the test strip into contact with the swab, and that’s it. A quarter of an hour later, a positive result is shown as a faint pink line.

The disadvantage of the test is that it can have two different types of user error. It is difficult to tell when the drops are coming out of the pipette and using too few drops can result in a false negative. So could wipe your nose the wrong way. Unlike the other tests, this one cannot tell if you made a mistake.

In addition to the prospect of user error, the test itself has problems with accuracy. BinaxNow is the cheapest test on the market, but it’s also the most likely bug, as about one in seven true infections is missing. Abbott warns that results “should be treated as suspected” and “do not rule out SARS-Cov-2”.

But a buyer won’t find the accuracy rate without digging into the fine print. The company also buries a critical requirement made by regulators: to compensate for the lower accuracy, consider using both tests in the kit at least 36 hours apart. I doubt a casual buyer will realize this. The two-test requirement is hardly mentioned in the instructions.

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Steven Gregory