CORONAVIRUS / COVID-19 PCR & ANTIBODY TEST

 What Is an Antibody Test?

An antibody test is a screening for things called antibodies in your blood. Your body makes these when it fights an infection, like COVID-19. The same thing happens when you get a vaccine, like a flu shot. That’s how you build immunity to a virus. You may also hear it called a serology test.

The antibody test isn’t checking for the virus itself. Instead, it looks to see whether your immune system -- your body’s defense against illness -- has responded to the infection.

How Does an Antibody Test Work?

A technician will take a bit of your blood, like through a finger prick. The test looks for one or both kinds of antibodies to SARS-CoV-2, the virus that causes COVID-19:

• IgM antibodies, which happen early in an infection
• IgG antibodies, which are more likely to show up later
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Most people have IgG antibodies about 14 days after symptoms start. They usually stay in your blood long after the infection goes away, but we don’t know how long that is for the new coronavirus.

What’s the Difference Between a Coronavirus Test and an Antibody Test?

A coronavirus test, sometimes called a diagnostic test, looks for signs of active virus. It’s simpler and faster than an antibody test. But it tells you only if you have the virus in your body at the moment when you’re tested.

An antibody test shows that you had the virus at some point in the past. It could be gone, or you could still be contagious.

Why Do We Need Antibody Testing?

You could have SARS-CoV-2 and not know it. Not everyone who gets it has symptoms. Experts hope antibody tests can give health officials a better idea of how common the virus is.

Once scientists know who has had the virus, they can find out how sick it makes most people. And they can study what happens if people who've had it come into contact with it again. Along with other scientific information, this can help researchers understand who might be immune to the virus.

Are Antibody Tests Accurate?

Companies make their own claims about the accuracy of their antibody tests. Some say it’s up to 100%. Government researchers are studying how well the tests are working, but it’s too early to say for sure.

The FDA says it will crack down on any manufacturer that sells a bad test.

It’s important to note that some tests can mistake IgM antibodies from other coronaviruses, such as common cold strains, for SARS-CoV-2 antibodies.

What does a Positive/Negative result mean?

Positive results are indicative of an active infection with a novel coronavirus. Results from this test should be interpreted in conjunction with patient’s medical history, clinical signs and symptoms. A negative result indicates no current COVID-19 infection at the time of testing or that your sample was collected too early in your infection. A negative result should be combined with clinical observations, patient history and epidemiological information.

How common are false positives and false negatives?

The PCR test for COVID-19 works by detecting genetic material from SARS-CoV-2, the virus that causes COVID-19. The genetic material from SARSCoV-2 cannot be confused with the genetic material from other viruses, so the COVID-19 diagnostic test is highly specific. This means it almost never gives a false positive. If you are tested for COVID-19, and the test comes back positive, you can be very sure that you are infected with this virus.

False negative results can occur. If a specimen collection is not done properly, or if you are in an early stage of infection or already partially recovered, your swab sample might not contain enough viral material to come back positive. If you have any symptoms of COVID-19, it is safest to assume you are infected and act accordingly, even if your diagnostic test comes back negative.

Priority is given to those with the following symptoms:

Fever

Cough

Shortness of breath

Chills

Repeated shaking with chills

Muscle pain

Headache

Sore throat

New loss of taste or smell

Congestion or runny nose

Nausea or vomiting

Diarrhea

People working or living in places such as skilled nursing facilities, group homes, residential care facilities, and persons experiencing homelessness.

People who were in close contact with someone with COVID-19.