Category: rapid antigens tests

An expert’s opinion on the use of rapid antigen tests to tackle COVID

As winter approaches and the holidays approach, the COVID-19 epidemic has reached a new concerning phase. The emergence of the omicron strain, along with rising infection rates, has left many individuals uncertain about their vacation plans.

On Dec. 2, President Joe Biden detailed a number of initiatives to address the COVID-19 epidemic, including allowing private insurance to compensate for at-home COVID-19 rapid antigen tests. Along with immunization, rapid antigen tests remain one of the most efficient methods of tracking and reducing SARS-CoV-2 transmission, the virus that causes COVID-19.

Even though COVID-19 rapid antigen tests have become ingrained in the majority of people’s daily lives, many individuals continue to have doubts regarding the distinction between antigen and PCR tests, as well as when and how to utilize them. learn more about different types of rapid antigen tests and how to use them at

I am a molecular scientist at the University of Massachusetts Chan Medical School. Since April 2020, I’ve been a member of a team working on a National Institutes of Health-funded effort called RADx Tech, which aims to assist firms in developing quick tests to diagnose COVID-19 infection.

How are fast antigen assays performed?

Rapid antigen tests are used to identify a component of SARS-CoV-2 protein known as an antigen. To begin, use a swab to collect a sample from your nose or mouth, as indicated. You combine the sample with a liquid that liquefies the virus. The liquid is then applied to a test strip that contains a narrow line of antibodies specific for SARS-CoV-2 painted on it. Antibodies are Y-shaped proteins that identify and bind to antigens. If the antibodies recognize the viral proteins or antigens, a colorful line indicates the presence of SARS-CoV-2 on the test strip.

These tests are useful since they are straightforward to administer and provide findings rapidly, generally within 15 minutes. Additionally, rapid antigen tests are quite affordable, costing between $10 and $15 for each test (though they are much cheaper in other countries). In comparison, PCR rapid antigen tests often need laboratory equipment and specialists, take 12 hours to several days to complete and cost $100 or more, but there are several free options.

Biden also mentioned plans to give 50 million free rapid antigen tests to community health care practitioners for those without insurance during his remarks. Be ready to respond swiftly: In late November, 100,000 individuals signed up for free antigen COVID rapid antigen tests in less than 24 hours in New Hampshire.

The Food and Drug Administration approved around a dozen rapid antigen tests for SARS-CoV-2 in early December 2021, indicating that these tests fulfill specific performance and accuracy requirements.

When should quick testing be used?

If you exhibit any of the symptoms of COVID-19, regardless of vaccination status, you should seek immediate rapid antigen tests using PCR or antigen.

SARS-CoV-2 is very contagious, even if you do not exhibit symptoms. The sooner you discover whether you have COVID-19, the sooner you may isolate yourself, preventing transmission to others. Early rapid antigen tests are particularly crucial since new medications, such as those developed by Merck and Pfizer, are most effective when given early in the course of an infection, just after symptoms manifest.

If you obtain a negative antigen test but continue to feel poorly, you may have gotten a false negative result. Isolate yourself from people and make an appointment with your physician to discuss your symptoms. If you get a positive test, you should remain at home and notify your health care physician immediately.

If you do not have symptoms but have been in close contact with someone who has COVID-19, the appropriate course of action is determined on your vaccination status. If you are completely vaccinated, the CDC advises waiting five to seven days following exposure to get a PCR or rapid antigen test. If you are not completely vaccinated, seek immediate medical attention. If you do not develop symptoms after exposure, you should be retested five to seven days later.

SARS-CoV-2, like many other respiratory viruses, takes many days to develop up in your body after exposure. Because the quantity of viral protein is very low at this early stage of infection, a fast test may miss your illness. This is why, for many antigen tests, serial rapid antigen tests over many days with at least 24 hours between tests are suggested. Rapid antigen tests are most accurate when an individual is infected since this is when the virus is most concentrated in the respiratory tract.

Serial antigen testing – often two to three tests per week – has been proven to be comparable to a single PCR test. Bear in mind that a test provides an estimate of your SARS-CoV-2 status at the time of the test. It is possible to test negative during the early stages of infection, particularly with antigen testing.

What is the future of COVID-19 at-home rapid antigen tests?

Despite everything we have learned, there is still much more to learn about the most effective approach to perform fast testing. Our research team is now performing many studies to bridge these gaps.

One of the questions we’re investigating via a program called STOP COVID-19 is how individuals utilize home rapid antigen tests when their infection risk is low vs high. For example, someone who wears a mask inside and avoids eating out is considered low risk, but someone who is not vaccinated and congregates with a large number of individuals without masks is considered high risk. 

Additionally, we want to know if individuals will comply with a rapid antigen tests routine after exposure and whether they will report their home test findings to their local department of public health.

Another significant subject our team is investigating is how antigen testing compares to polymerase chain reaction (PCR) tests for diagnosing COVID-19 in patients who are positive but do not exhibit symptoms. Separately, national research called Test Us at Home is gathering critical data that will assist us …

Different rapid antigen tests and how they work

For around 20-30 years, PCR has been extensively utilized in research and medicine to discover genetic information. RT-PCR is a modified form of the method that is utilized when RNA is identified, and it is currently being used to identify SARS-CoV-2, the virus that causes COVID-19. This sort of rapid antigen tests has commonly been employed as a first-line diagnostic for COVID-19 because it detects the viral RNA directly.

RT-PCR assays are relatively rapid, sensitive, and reliable, with findings available in 3-4 hours, however, this time is often extended if samples must first be forwarded to specialized external labs (6-8 hours on average).

Numerous diagnostic and research businesses manufacture RT-PCR products, tests, and equipment, ensuring widespread availability of the technique. Certain RT-PCR assays are produced as an ‘all-in-one’ kit, which minimizes laboratory handling and contamination risk.

How it operates

After collecting a sample, chemicals are employed to deplete it of proteins, lipids, and other components, leaving just RNA. This will be a combination of the individual’s genetic material and any viral RNA that may be present.

The enzymes in the rapid antigen tests kit convert the RNA to DNA, which is amplified to enable virus identification using a PCR machine that cycles the rapid antigen tests temperature in such a way that about 35 billion copies of viral DNA are produced for each viral RNA strand that was initially present.

Typically, fluorescent markers are employed to attach to amplified DNA and generate light that can be read by the machine to provide the rapid antigen tests result. A positive rapid antigen tests is one in which the intensity of the light emitted inside the sample exceeds a predetermined threshold. The number of PCR temperature cycles necessary to attain the fluorescence threshold is recorded, providing an estimate of the viral load in the patient sample.

What are rapid antigen tests designed to detect?

RT-PCR is used to determine whether or not viral RNA is present in patient samples. This is accomplished by encoding and amplifying segments of the virus’s genetic material, often the Spike protein, the N protein, or the Envelope (see picture).

To quantify viral RNA, it is transformed to DNA, duplicated several times using multiple temperature cycles in a PCR machine, and then detected using fluorescent markers. If the quantity of fluorescence increases over a specific threshold, this indicates the presence of the virus. The number of temperature cycles required for the machine to attain this threshold is recorded in order to determine the amount of virus contained in the patient sample. The fewer cycles, the greater the amount of virus present. Typically, these samples are obtained by swabbing the nose or throat with either long or short swabs, although they may also be obtained in other methods. Collecting samples from areas where the virus is shed or proliferating increases the rapid antigen tests‘ accuracy. Click here to read how to use a rapid antigen test kit.

What does the outcome imply?

When conducted on a sample from an infected area of the body during an active illness, an RT-PCR rapid antigen tests is very sensitive and moderately reliable.

A positive PCR result indicates that the individual from whom the sample was collected is presently infected with the virus.

Negative PCR result: – A negative PCR result may indicate that the individual is not presently infected with this virus, the virus is not present at the place from where the sample was collected, the sample was of low quality, or the infection is too early or late to detect the replicating virus. This is why negative test findings need the collection of fresh patient samples a few days later to eliminate the possibility of missing an infected individual.

The RT-PCR rapid antigen tests cannot determine if a person had the virus and subsequently cleared it after the end of the COVID-19 sickness, or whether a person had the disease since it detects an only active virus.

Advantages and disadvantages

  • RT-PCR is widely acknowledged by scientists and medical personnel as a reliable and well-documented technology.
  • Because RT-PCR is so widely used in research and medicine, the technology for rapid antigen tests for COVID-19 is already in place.
  • RT-PCR may identify active illness infections, enabling medical personnel to decide who is infected and who is not.


  • Because RT-PCR is based on collecting and identifying viruses, it may overlook individuals who have cleared the virus and recovered from sickness. learn more ways of recovering form sickness at
  • Because viral distribution in the respiratory tract differs across individuals, even if a person is infected, the virus may be detected only in sputum or a nasopharyngeal swab, but not always in both sites concurrently.
  • Real-time polymerase chain reaction (RT-PCR) for COVID-19 can only determine whether a person is presently infected with this specific coronavirus. It is unable to offer information on further illnesses or symptoms.

Antigen examinations

Rapid and precise rapid antigen tests is critical for the containment of a highly infectious virus such as SARS-CoV-2. While PCR tests are reliable, they might take a long time to complete. While rapid antigen tests, the second primary form of coronavirus test, are much quicker, they are also significantly less accurate.

Antigens are substances that elicit an immunological response in the body — they initiate the production of antibodies. These assays look for antigens from the SARS-CoV-2 virus using laboratory-made antibodies.

To conduct an antigen test, a sample is first treated with a solution comprising salt and soap, which dissolves cells and other particles. Then you add this liquid to a test strip that has been coated in a narrow line with antibodies specific for SARS-CoV-2.

Antibodies on the test strip, like those in your body, will bind to any antigen in the sample. If the antibodies recognize coronavirus antigens, a colored line indicates the presence of SARS-CoV-2 on the rapid antigen tests strip.

Antigen testing provides a variety of advantages. To begin, they are so simple to do and interpret that …

A critical look at rapid antigens tests

The coronavirus epidemic continues to have a significant impact on our everyday lives, infecting hundreds of thousands of individuals each week. COVID-19 rapid antigen tests are a very effective method of protecting yourself and your family. However, which exam is appropriate for you? Dr. Christopher Carpenter, a Beaumont infectious disease specialist and chair of internal medicine, has the answers.

What are the many COVID-19 test types?

There are two primary kinds of COVID-19 rapid antigen tests available at the moment.

  • Viral testing may be used to determine whether a person is currently infected with COVID-19. Nucleic acid amplification rapid antigen tests (NAATs) and antigen testing are two frequent forms of viral diagnostics. You may have heard NAATs referred to as polymerase chain reaction (PCR) testing. Vaccination will not result in a positive result on these rapid antigen tests.
  • Antibody rapid antigen tests, often called serology tests, may determine whether you have ever been infected with the coronavirus, but they cannot identify an active infection. Depending on the antibody target (i.e., those directed against the spike protein), this test may potentially detect a response to past immunization in an individual who has never been sick.

While certain viral tests may be performed on-site or even at home, others must be transported to a laboratory for processing.

“While on-site testing is convenient and produces findings quickly, it has significant limits,” Dr. Carpenter said. “In many circumstances, operators are restricted in their ability to complete a particular number of rapid antigen tests within a certain amount of time. Sensitivity and precision might sometimes be a problem.”

While laboratory tests are more precise, they may take longer to complete.

Which Examination Should You Take?

“Which test is best for you is situation-dependent,” Dr. Carpenter said. “Some rapid antigen tests are only authorized for persons who are already experiencing symptoms, and they should not be used for screening if you are feeling well. The best test is one that provides the most accurate result in the shortest amount of time.”

When time is critical, an antigen or fast test may be the best option. Numerous rapid antigen tests are now accessible as home test kits, which eliminates the need to visit a health care institution. If you have the patience to await the findings of a laboratory-based test, you will often obtain the most accurate results. learn more about rapid antigen tests by clicking here.

While no test is perfect, the ones now available are very accurate when done properly. If you choose an at-home test, it is critical to carefully follow the directions for the best results. Individuals who continue to suffer symptoms after a negative COVID-19 test may seek repeat testing.

When should you get tested for COVID-19?

COVID-19 rapid antigen tests are beneficial for confirming or ruling out an infection, particularly as we approach flu season. Not only may the outcome impact treatment choices, but it can also assist safeguard individuals in your immediate vicinity. learn more about clinical supplies at

The CDC advises that everyone who exhibits symptoms consistent with COVID-19 be tested, even those who are completely vaccinated or have been infected before. Additionally, those who have not been vaccinated but have traveled, attended big meetings, or been in poorly ventilated interior settings should be examined.

Individuals who have been completely vaccinated and have been exposed to someone who has COVID-19 should seek rapid antigen tests to confirm they have not caught the virus. While the individual may be symptom-free, they may still transmit the illness to others. If positive, rapid antigen tests assist in preventing this with adequate isolation.

  • If you feel you have been exposed to COVID-19 and are completely vaccinated, you should test 5-7 days following your original exposure. 
  • If you believe you have been exposed to COVID-19 but are not fully vaccinated, you should test immediately. If your test result is negative, be certain to retest (5-7 days after the initial exposure or immediately after symptoms develop).

Anyone wanting to go overseas or returning to the United States after an international trip may be needed to have a recent negative COVID-19 test. Because specific restrictions vary per location, it is important to verify and make the necessary preparations before visiting.

How to safeguard oneself while awaiting test results

“If you are asymptomatic and undergoing regular rapid antigen tests, such as before to travel, there are no restrictions other than the advised precautions,” Dr. Carpenter says.

Individuals who have not been vaccinated and have been exposed to COVID-19 should consider self-quarantine. Individuals who have been vaccinated may not be required to quarantine, but they should check themselves for signs and continue to take measures. The CDC advises isolation for anybody exhibiting COVID-19 symptoms while awaiting test results.

Despite extensive rapid antigen tests, Dr. Carpenter underlines that immunization remains the most effective method of preventing COVID-19.

Investigating genetic evidence

For any kind of test, the initial step is to get a sample from the patient. This might be a swab of the nose or a little amount of saliva.

For PCR rapid antigen tests, the following step is an amplification of the genetic material, which allows for detection of even a minute quantity of coronavirus genes in the patient’s sample. This is accomplished via the use of a process known as a polymerase chain reaction. A health care professional collects the sample and uses an enzyme to convert it to double-stranded DNA. 

The DNA is then heated in the presence of a solution containing an enzyme called a polymerase, causing it to split into two single-stranded DNA fragments. The temperature is dropped, and polymerase attaches to and replicates the single-stranded DNA with the assistance of a short bit of guide DNA called a primer. The primers are designed to amplify just coronavirus DNA. You have now replicated coronavirus DNA twice from the initial RNA fragment.

Laboratory machinery performs these heating and cooling cycles 30–40 times, doubling the DNA to a billion copies. …