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Are At-Home COVID-19 Tests Worth it?

In the fight to bring the coronavirus under control, our primary care doctors at Cohen Medical Associates in Delray Beach continue to emphasize universal vaccinations as the primary weapon in our arsenal. But rapid at-home test kits for COVID-19 also have a place.

Free walk-up testing sites are readily available here in South Florida. Click here or here to find testing sites. There may be times when you can’t get to a testing site, or you’d like something that can give you faster results. This is where rapid at-home tests can be useful.

Think of times, for instance, when your workplace or child’s school suspects a sniffle or cough might be something more than seasonal allergies and says you can’t return until you have a negative coronavirus test.

While they aren’t a replacement for vaccinations, and they have some issues with reliability, as we’ll explain below, they can help cut down chances for transmission. Especially because testing can occur more regularly.

The good news is that earlier this month, the Biden administration announced that it will buy $1 billion worth of rapid, at-home tests, which are currently in short supply. They expect the number of tests to quadruple by December because of this.

Testing has a place

As we’ll explain in a moment, different tests can produce different results depending on:

  • type of test
  • test sensitivity
  • whether the testing procedure was followed precisely
  • when it’s administered
  • or other factors

But that doesn’t mean they’re useless.

One study published last month in the journal Mayo Clinic Proceedings found that mandatory PCR tests for coronavirus administered within three days of flying, coupled with rapid antigen tests just before boarding, drastically reduced the number of passengers later found to have COVID-19.

The study, conducted by the Mayo Clinic, Delta Air Lines, and the Georgia Department of Health, looked at 9,853 flyers who were tested between December 2020 and May 2021 within 72 hours of departure from New York to Italy.

Of those, only five people had a current infection and were barred from their flight. The rest flew and avoided quarantine on arrival in Italy.

Four types of at-home COVID-19 tests

Let’s briefly recap the various types of coronavirus testing available.

Currently, there are four main types of tests on the market. Medical professionals administer two, while two are available for home use.

PCR tests

This is the gold standard of COVID-19 testing. If performed correctly by trained personnel, polymerase chain reaction (PCR) tests are highly accurate because they can detect the signature pieces of RNA from the virus in the sample. Nevertheless, some studies have suggested that as many as 30 percent of PCR test results are inaccurate (about the same percentage as the standard flu test).

Antibody blood tests

These tests cannot determine whether an individual has an active infection. Instead, they use blood samples to look for antibodies that the body has already produced to fight off an infection of COVID-19. The test indicates whether the person was infected with the virus (or has recently been vaccinated), but cannot tell whether the virus is still active.

Because it takes from 10 to 12 days following infection for your body to begin producing antibodies to the virus, antibody blood tests can’t be used to screen for the virus.

Antigen tests

Most of the rapid tests available on the market are antigen tests. As with the PCR test, antigen tests use a nasal swab to detect traces of the coronavirus’ distinctive protein cover. These are even more dependent on timing than the PCR test. If it’s too early in the course of infection, the virus may not have started shedding detectable pieces of protein.

The results of antigen tests are available sooner than the PCR test—within 10 to 15 minutes—but are also up to 50 percent less accurate, especially if someone is asymptomatic or early in their infection and thus has a lower viral load.

The CDC advises those who test negative on an antigen test to have a PCR test to confirm the results.

Saliva tests

The U.S. Food and Drug Administration (FDA) has approved several saliva-based tests for at-home use. You spit into a vial then send it off for analysis. Results are available in as little as 24 hours.

They are more popular with the general public because they are easier and cheaper. Studies have shown they are at least as accurate as of the PCR test.

Testing limitations

Medical tests are rarely 100 percent accurate, and the coronavirus tests are no exception, as we explained above.

And even if a test result is accurate, the moment you come into contact with an infected person you can become infected, making the test meaningless.

So if you do not have the vaccine, please do so as soon as possible. This is the best way to protect yourself and others.

Meanwhile, the government promises we’ll have 200 million rapid antigen tests a month available beginning in December. Always beware of fake tests. Check the FDA’s website for a list of antigen tests that have received Emergency Use Authorization (EAU).

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