What are the pros and cons of each available COVID-19 test?
What are the pros and cons of each available COVID-19 test?
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Correction April 8, 2022: A previous version of this article incorrectly compared the sensitivity and specificity of antigen and molecular COVID-19 tests. Molecular tests have high sensitivity and high specificity, while antigen tests have moderate to high sensitivity and high specificity. The previous version incorrectly stated the opposite. The article has now been updated with the correct references. Health Desk regrets the error.
Correction April 8, 2022: A previous version of this article incorrectly compared the sensitivity and specificity of antigen and molecular COVID-19 tests. Molecular tests have high sensitivity and high specificity, while antigen tests have moderate to high sensitivity and high specificity. The previous version incorrectly stated the opposite. The article has now been updated with the correct references. Health Desk regrets the error.
There are 3 main types of COVID-19 tests. Two are diagnostic (molecular and antigen tests), which means they show active infections. One test type looks for antibodies that occur in the body following a previous infection (also known as antibody tests). 1) Molecular tests (polymerase chain reaction (PCR) tests, viral RNA tests, and nucleic acid tests) are completed using nasal swabs, throat swabs, and through testing bodily fluids like saliva. These tests look for evidence of genetic material from the virus. They have a low rate of false-positive results (when a test says you have the virus, but you do not). Using a deep nasal swab PCR test that collects viral material at the back of nose, near your throat, is the most trusted option of the molecular tests. That's because it is the most accurate, and there is a higher amount of virus in that area of the body than anywhere else. These tests are highly sensitive, which means they are able to accurately determine when a person actually has an infection. However, the method is uncomfortable, the results can take hours to days, they are the most expensive to do, and can be overly sensitive and pick up inactive virus fragments when a person no longer has an active infection. 2) Antigen tests are completed using nasal or throat swabs and they look for proteins (antigens) from the virus. Most people are familiar with this technology because it is commonly seen in pregnancy tests. These results are available in as little as 10 minutes, the test is less expensive than other forms, and uses simpler technology than PCR tests. These tests are usually mostly accurate for positive results, but might require a molecular test to confirm if a person really is negative because they can often have a high rate of false-negative results. 3) Antibody tests are different than diagnostic tests because they are blood tests that look for a former COVID-19 infection through the presence of antibodies, a protein that latches on to foreign invaders in the body - in this case, COVID-19 - neutralizes them, and then remains in a person's system after infection. A person produces COVID-19 antibodies when they are exposed to the virus, so an antibody test can show whether or not someone has been infected in the past. Antibody test results are usually available within a few days. However, these tests produce some false-negatives and we don't know enough about how long antibodies last after exposure or infections, how long any immunity might last, and how many antibodies are needed in a person who has recovered from the virus to show a positive test result. There are many different elements involved in how accurate or reliable tests may be at the time they are taken and at the stage of exposure and infection each person is presently in, and every testing type has different strengths or weaknesses. It is important to remember that the best test for each person should be chosen with their doctor on an individual basis.
There are 3 main types of COVID-19 tests. Two are diagnostic (molecular and antigen tests), which means they show active infections. One test type looks for antibodies that occur in the body following a previous infection (also known as antibody tests). 1) Molecular tests (polymerase chain reaction (PCR) tests, viral RNA tests, and nucleic acid tests) are completed using nasal swabs, throat swabs, and through testing bodily fluids like saliva. These tests look for evidence of genetic material from the virus. They have a low rate of false-positive results (when a test says you have the virus, but you do not). Using a deep nasal swab PCR test that collects viral material at the back of nose, near your throat, is the most trusted option of the molecular tests. That's because it is the most accurate, and there is a higher amount of virus in that area of the body than anywhere else. These tests are highly sensitive, which means they are able to accurately determine when a person actually has an infection. However, the method is uncomfortable, the results can take hours to days, they are the most expensive to do, and can be overly sensitive and pick up inactive virus fragments when a person no longer has an active infection. 2) Antigen tests are completed using nasal or throat swabs and they look for proteins (antigens) from the virus. Most people are familiar with this technology because it is commonly seen in pregnancy tests. These results are available in as little as 10 minutes, the test is less expensive than other forms, and uses simpler technology than PCR tests. These tests are usually mostly accurate for positive results, but might require a molecular test to confirm if a person really is negative because they can often have a high rate of false-negative results. 3) Antibody tests are different than diagnostic tests because they are blood tests that look for a former COVID-19 infection through the presence of antibodies, a protein that latches on to foreign invaders in the body - in this case, COVID-19 - neutralizes them, and then remains in a person's system after infection. A person produces COVID-19 antibodies when they are exposed to the virus, so an antibody test can show whether or not someone has been infected in the past. Antibody test results are usually available within a few days. However, these tests produce some false-negatives and we don't know enough about how long antibodies last after exposure or infections, how long any immunity might last, and how many antibodies are needed in a person who has recovered from the virus to show a positive test result. There are many different elements involved in how accurate or reliable tests may be at the time they are taken and at the stage of exposure and infection each person is presently in, and every testing type has different strengths or weaknesses. It is important to remember that the best test for each person should be chosen with their doctor on an individual basis.
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What our experts say
There are 3 main types of COVID-19 tests. Two are diagnostic (molecular and antigen tests), which means they show active infections. One test type looks for antibodies that occur in the body following a previous infection (also known as antibody tests).
1) Molecular tests (polymerase chain reaction (PCR) tests, viral RNA tests, and nucleic acid tests) are completed using nasal swabs, throat swabs, and through testing bodily fluids like saliva. These tests look for evidence of genetic material from the virus. They have a low rate of false-positive results (when a test says you have the virus, but you do not) but a higher rate of false-negative results (when a test says you do not have the virus, but you really do).
Using a deep nasal swab PCR test that collects viral material at the back of nose, near your throat, is the most trusted option of the molecular tests. That's because it is the most accurate, and there is a higher amount of virus in that area of the body than anywhere else. These tests are highly sensitive, which means they are able to accurately determine when a person actually has an infection. However, the method is uncomfortable, the results can take hours to days, they are the most expensive to do, and can be overly sensitive and pick up inactive virus fragments when a person no longer has an active infection.
2) Antigen tests are completed using nasal or throat swabs and they look for proteins (antigens) from the virus. Most people are familiar with this technology because it is commonly seen in pregnancy tests. These results are available in as little as 10 minutes, the test is less expensive than other forms, and uses simpler technology than PCR tests. These tests are usually highly accurate for positive results, but might require a molecular test to confirm if a person really is negative because they can often have a high rate of false-negative results.
3) Antibody tests are different than diagnostic tests because they are blood tests that look for a former COVID-19 infection through the presence of antibodies, a protein that latches on to foreign invaders in the body - in this case, COVID-19 - neutralizes them, and then remains in a person's system after infection. A person produces COVID-19 antibodies when they are exposed to the virus, so an antibody test can show whether or not someone has been infected in the past. Antibody test results are usually available within a few days. However, these tests produce a lot of false-negatives and we don't know enough about how long antibodies last after exposure or infections, how long any immunity might last, and how many antibodies are needed in a person who has recovered from the virus to show a positive test result.
There are many different elements involved in how accurate or reliable tests may be at the time they are taken and at the stage of exposure and infection each person is presently in, and every testing type has different strengths or weaknesses. It is important to remember that the best test for each person should be chosen with their doctor on an individual basis.
There are 3 main types of COVID-19 tests. Two are diagnostic (molecular and antigen tests), which means they show active infections. One test type looks for antibodies that occur in the body following a previous infection (also known as antibody tests).
1) Molecular tests (polymerase chain reaction (PCR) tests, viral RNA tests, and nucleic acid tests) are completed using nasal swabs, throat swabs, and through testing bodily fluids like saliva. These tests look for evidence of genetic material from the virus. They have a low rate of false-positive results (when a test says you have the virus, but you do not) but a higher rate of false-negative results (when a test says you do not have the virus, but you really do).
Using a deep nasal swab PCR test that collects viral material at the back of nose, near your throat, is the most trusted option of the molecular tests. That's because it is the most accurate, and there is a higher amount of virus in that area of the body than anywhere else. These tests are highly sensitive, which means they are able to accurately determine when a person actually has an infection. However, the method is uncomfortable, the results can take hours to days, they are the most expensive to do, and can be overly sensitive and pick up inactive virus fragments when a person no longer has an active infection.
2) Antigen tests are completed using nasal or throat swabs and they look for proteins (antigens) from the virus. Most people are familiar with this technology because it is commonly seen in pregnancy tests. These results are available in as little as 10 minutes, the test is less expensive than other forms, and uses simpler technology than PCR tests. These tests are usually highly accurate for positive results, but might require a molecular test to confirm if a person really is negative because they can often have a high rate of false-negative results.
3) Antibody tests are different than diagnostic tests because they are blood tests that look for a former COVID-19 infection through the presence of antibodies, a protein that latches on to foreign invaders in the body - in this case, COVID-19 - neutralizes them, and then remains in a person's system after infection. A person produces COVID-19 antibodies when they are exposed to the virus, so an antibody test can show whether or not someone has been infected in the past. Antibody test results are usually available within a few days. However, these tests produce a lot of false-negatives and we don't know enough about how long antibodies last after exposure or infections, how long any immunity might last, and how many antibodies are needed in a person who has recovered from the virus to show a positive test result.
There are many different elements involved in how accurate or reliable tests may be at the time they are taken and at the stage of exposure and infection each person is presently in, and every testing type has different strengths or weaknesses. It is important to remember that the best test for each person should be chosen with their doctor on an individual basis.
Context and background
Having massive testing available for large populations has been a challenge throughout the COVID-19 pandemic. We often hear about testing challenges in the news without knowing exactly what tests they are, what their results mean, and if we can trust them. Testing will continue to be a vital component of the COVID-19 response across the world and will help determine how many people in a population have been potentially infected, and if any outbreaks might be occurring. Using different tests for different people at different times in the exposure and infection process is a decision that should be made between a patient and their doctors, who can interpret the results and help them make decisions about how to proceed. Unless testing is consistently available for every person frequently, people should continue wearing masks, practicing social distancing, washing their hands often, and engaging in other prevention strategies.
Having massive testing available for large populations has been a challenge throughout the COVID-19 pandemic. We often hear about testing challenges in the news without knowing exactly what tests they are, what their results mean, and if we can trust them. Testing will continue to be a vital component of the COVID-19 response across the world and will help determine how many people in a population have been potentially infected, and if any outbreaks might be occurring. Using different tests for different people at different times in the exposure and infection process is a decision that should be made between a patient and their doctors, who can interpret the results and help them make decisions about how to proceed. Unless testing is consistently available for every person frequently, people should continue wearing masks, practicing social distancing, washing their hands often, and engaging in other prevention strategies.
Resources
- Which test is best for COVID-19? (HMS)
- Which COVID test is best? Pros and cons of coronavirus detection methods (UTS)
- Rapid tests. PCR. Antigen. Antibody. These are coronavirus test options, and what’s coming (SFC)
- A Closer Look at Coronavirus Disease 2019 (COVID-19) Diagnostic Testing (United States Food & Drug Administration)
- Which test is best for COVID-19? (HMS)
- Which COVID test is best? Pros and cons of coronavirus detection methods (UTS)
- Rapid tests. PCR. Antigen. Antibody. These are coronavirus test options, and what’s coming (SFC)
- A Closer Look at Coronavirus Disease 2019 (COVID-19) Diagnostic Testing (United States Food & Drug Administration)
