Test pcr. COVID-19 Testing: What You Need to Know
What is the difference between a PCR and antigen COVID-19 test? How do they work, and what are their strengths and weaknesses? Explore the details about COVID-19 testing options, including no-cost testing for those without insurance.
Understanding the Difference Between PCR and Antigen COVID-19 Tests
At this point in the COVID-19 pandemic, you or someone you know has likely received at least one type of COVID-19 test. But do you know the difference between a PCR test and an antigen test, and the strengths and weaknesses of each?
As a molecular biologist who has been part of a team working on the National Institutes of Health-funded RADx program to help develop rapid tests for SARS-CoV-2 detection, I can provide some insights into the two major types of COVID-19 tests: molecular tests (better known as PCR tests) and antigen tests.
How PCR Tests Work
PCR tests are extremely accurate, but they require specialized laboratory equipment and trained personnel to process the samples. The test works by detecting the genetic material of the SARS-CoV-2 virus, known as RNA, and amplifying it so that it can be detected. This process is called reverse transcription-polymerase chain reaction (RT-PCR).
PCR tests are considered the gold standard for COVID-19 diagnosis because they can detect even very small amounts of the virus, making them highly sensitive. However, this sensitivity also means that PCR tests can sometimes detect remnants of the virus even after a person has recovered and is no longer infectious.
How Antigen Tests Work
Antigen tests, on the other hand, detect specific proteins on the surface of the SARS-CoV-2 virus. These tests are simpler and faster to perform than PCR tests, often providing results in just 15-30 minutes. They do not require specialized laboratory equipment, making them more accessible and convenient for widespread testing.
However, antigen tests are generally less sensitive than PCR tests, meaning they are more likely to miss a positive case, especially in individuals with low viral loads. This can result in false-negative results, where the test indicates the person is not infected when they actually are.
Strengths and Weaknesses of Each Test
The choice between a PCR test and an antigen test depends on the specific situation and needs. PCR tests are more accurate and sensitive, making them the preferred choice for diagnosis, especially in the early stages of infection. Antigen tests, while less accurate, are faster and more accessible, making them useful for screening and quick turnaround situations, such as before events or travel.
Accessing No-Cost COVID-19 Testing
If you do not have health insurance, you can still access no-cost COVID-19 testing through the Increasing Community Access to Testing (ICATT) program. This program provides free testing for people without insurance who are experiencing COVID-19 symptoms or have been exposed to someone with the virus.
To find an ICATT testing location near you, visit the website and enter your zip code. You can then schedule an appointment directly with the provider. Some ICATT locations also offer the “Test to Treat” option, where you can receive a prescription for COVID-19 treatment on-site if you test positive.
Additional COVID-19 Testing Resources
For more information on COVID-19 testing, including the different types of tests, when to get tested, and where to find community-based testing sites, visit the following resources:
- CDC Testing for COVID-19 webpage
- HHS Community-Based Testing Sites for COVID-19 website
- CDC Symptoms of COVID-19 page
- CDC What to Do If You Were Exposed to COVID-19 page
Staying Informed and Protected
Understanding the differences between PCR and antigen COVID-19 tests, as well as accessing no-cost testing options, can help you make informed decisions about your health and safety during the ongoing pandemic. Stay informed, get tested when necessary, and continue to follow recommended safety measures to protect yourself and your community.
No-Cost COVID-19 Testing
Search for No-Cost COVID-19 Testing
After the Public Health Emergency expires on May 11, 2023: The CDC ICATT program will likely continue with a smaller site network that supports testing and disease surveillance needs at non-emergency levels. ICATT will continue to provide no-cost COVID-19 testing for people without health insurance with symptoms related to COVID-19 or who were exposed to someone with COVID-19.
Search for a location that offers no-cost COVID-19 testing
Search for a location convenient for you, then visit the provider’s website to make an appointment.
COVID-19 tests found through this site are available at no cost for people without health insurance
Visit one of these locations to get a test at no cost to you. People without health insurance do not have to pay for COVID-19 testing at Increasing Community Access to Testing (ICATT) locations.
Types of COVID-19 tests offered at these locations
The types of COVID-19 tests offered vary by location and provider but include laboratory-based nucleic acid amplification tests (NAATs) and rapid point-of-care (POC) testing.
How to schedule an appointment for a COVID-19 test
This website helps you find ICATT COVID-19 testing locations and contact information for the providers. Because every provider handles appointments differently, schedule your appointment directly with the provider you choose.
Test to Treat locations
If you test positive at one of these sites and certain treatments are appropriate for you, you can receive a prescription from a healthcare provider and have that prescription filled all in one location. Visit the HHS Test to Treat webpage and the Test to Treat locator for more information.
COVID-19 vaccines near you
Visit vaccines.gov to find a COVID-19 vaccine location near you.
Who should get tested at these locations?
Get a test at one of these locations if you do not have health insurance and:
- Are experiencing symptoms of COVID-19
- Have been in close contact with someone who has recently tested positive for COVID-19
Other COVID-19 testing options in your community
This site does not display all the locations in the United States where COVID-19 testing is available.
Visit the Department of Health and Human Services’ (HHS’s) Community-Based Testing Sites for COVID-19 website to find out about other community-based testing sites for COVID-19. You can visit your state, tribal, local, and territorial health department’s website to find the latest local information on testing.
Information from CDC about COVID-19 testing
Continue visiting the CDC Testing for COVID-19 webpage for information about testing, types of tests, when to get tested, and more.
For additional information about ICATT or the COVID-19 testing locator, visit the ICATT website.
Additional Resources:
-
COVID.gov – Find COVID-19 guidance for your community -
Test to Treat | HHS/ASPR -
Your Health | COVID-19 | CDC -
COVID-19 Testing: What You Need to Know | CDC -
Symptoms of COVID-19 | CDC -
What to Do If You Were Exposed to COVID-19 | CDC -
Nucleic Acid Amplification Tests (NAATs) | CDC -
Guidance for SARS-CoV-2 Rapid Testing Performed in Point-of-Care Settings | CDC
What’s the difference between a PCR and antigen COVID-19 test?
All COVID-19 tests start with a sample, but the scientific process goes very differently after that.
Morsa Images/Digital Vision via Getty Images
(Spanish language version: https://theconversation.com/pruebas-covid-de-pcr-o-antigenos-conoce-cuales-son-las-diferencias-173483)
At this point in the pandemic, you or someone you know has probably received at least one COVID-19 test. But do you know which kind of test you got and the strengths and weaknesses of these different tests?
I’m a molecular biologist, and since April 2020 I’ve been part of a team working on a National Institutes of Health-funded program called RADx that is helping innovators develop rapid tests to detect when a person is infected with SARS-CoV-2, the virus that causes COVID-19.
Two major types of tests are used to diagnose infection with SARS-CoV-2: molecular tests – better known as PCR tests – and antigen tests. Each detects a different part of the virus, and how it works influences the test’s speed and relative accuracy. So what are the differences between these types of tests?
PCR tests are extremely accurate but require special lab equipment – like the PCR heating machine seen here – and can take hours or days to perform.
Karl Mumm via Wikimedia Commons, CC BY-SA
Looking for genetic evidence
The first step for either kind of test is to get a sample from the patient. This can be a nasal swab or a bit of saliva.
For PCR tests, the next step is amplification of genetic material so that even a small amount of coronavirus genes in the patient’s sample can be detected. This is done using a technique called a polymerase chain reaction. A health care worker takes the sample and treats it with an enzyme that converts RNA into double-stranded DNA. Then, the DNA is mixed with a solution containing an enzyme called a polymerase and heated, causing the DNA to separate into two single-stranded DNA pieces. The temperature is lowered, and polymerase, with the help of a small piece of guide DNA called a primer, binds to the single-stranded DNA and copies it. The primers ensure that only coronavirus DNA is amplified. You’ve now created two copies of coronavirus DNA from the original one piece of RNA.
Laboratory machines repeat these heating and cooling cycles 30 to 40 times, doubling the DNA until there are a billion copies of the original piece.
The amplified sequence contains fluorescent dye that is read by a machine.
The amplifying property of PCR allows the test to successfully detect even the smallest amount of coronavirus genetic material in a sample. This makes it a highly sensitive and accurate test. With accuracy that approaches 100%, it is the gold standard for diagnosing SARS–CoV–2.
However, PCR tests have some weaknesses too. They require a skilled laboratory technician and special equipment to run them, and the amplification process can take an hour or more from start to finish. Usually only large, centralized testing facilities – like hospital labs – can conduct many PCR tests at a time. Between sample collection, transportation, amplification, detection and reporting, it can take from 12 hours to five days for a person to get results back. And finally, they aren’t cheap at $100 or more per test.
Rapid antigen tests – like the two seen here showing negative results – are much faster and easier to perform but are less sensitive than PCR tests.
Lennardywlee via Wikimedia Commons, CC BY-SA
Antigen tests
Rapid, accurate tests are essential to contain a highly contagious virus like SARS-CoV-2. PCR tests are accurate but can take a long time to produce results. Antigen tests, the other major type of coronavirus test, while much faster, are less accurate.
Antigens are substances that cause the body to produce an immune response – they trigger the generation of antibodies. These tests use lab-made antibodies to search for antigens from the SARS-CoV-2 virus.
To run an antigen test, you first treat a sample with a liquid containing salt and soap that breaks apart cells and other particles. Then you apply this liquid to a test strip that has antibodies specific to SARS-CoV-2 painted on it in a thin line.
Just like antibodies in your body, the ones on the test strip will bind to any antigen in the sample. If the antibodies bind to coronavirus antigens, a colored line appears on the test strip indicating the presence of SARS-CoV-2.
Antigen tests have a number of strengths. First, they are so easy to use that people with no special training can perform them and interpret the results – even at home. They also produce results quickly, typically in less than 15 minutes. Another benefit is that these tests can be relatively inexpensive at around $10-$15 per test.
Antigen tests do have some drawbacks. Depending on the situation, they can be less accurate than PCR tests. When a person is symptomatic or has a lot of virus in their system, antigen tests are very accurate. However, unlike molecular PCR tests, antigen tests don’t amplify the thing they are looking for. This means there needs to be enough viral antigen in the sample for the antibodies on the test strip to generate a signal. When a person is in the early stages of infection, not a lot of virus is in the nose and throat, from which the samples are taken. So, antigen tests can miss early cases of COVID-19. It’s also during this stage that a person has no symptoms, so they are more likely to be unaware they’re infected.
More tests, better knowledge
A few antigen tests are already available over the counter, and on Oct. 4, 2021, the Food and Drug Administration granted emergency use authorization to another at-home antigen test. The U.S. government is also pushing to make these tests more available to the public.
At RADx, the project I am a part of, we are currently conducting clinical studies to get a better understanding of how antigen tests perform at various stages of infection. The more data scientists have on how accuracy changes over time, the more effectively these tests can be used.
Understanding the strengths and limitations of both PCR and antigen tests, and when to use them, can help to bring the COVID-19 pandemic under control. So the next time you get a COVID-19 test, choose the one that is right for you.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Take a PCR test for coronavirus Covid-19 in Samara
Method of determination
PCR with real-time detection.
Vector-Best test system, Russia.
Determination of SARS-CoV-2 virus RNA (all types of known strains, including Delta, Omicron and its variants Stealth-Omicron, Centaur, Arcturus, etc.)
Test material
Swab from the mucous membrane of the nasopharynx and/or oropharynx
For testing at medical offices, you must present SNILS and an identity document.
In the event of a positive or doubtful result for COVID-19 and , if necessary, confirmatory testing, a biomaterial sample can be sent to an authorized reference laboratory in accordance with SP 3.1.3597-20, in connection with which the established deadline for the study can be increased to .
Synonyms : Covid-19; New coronavirus infection; RNA of the new coronavirus; SARS-CoV-2 RNA in a smear from the nasopharyngeal and/or oropharyngeal mucosa.
Comprehensive laboratory diagnosis of coronavirus COVID-19; New Coronavirus RNA in nasopharyngeal and/or oropharyngeal smear.
Brief information about SARS-CoV-2 (COVID-19) infection
SARS-CoV-2 belongs to a large family of RNA viruses called coronaviruses (lat. Coronaviridae) that cause respiratory diseases. Currently, four types of coronaviruses (HCoV-229) are known to circulate among the population.E, -OC43, -NL63 and -HKU1), which are present all year round in the structure of SARS and, as a rule, cause mild to moderate damage to the upper respiratory tract. The coronavirus family also includes the dangerous SARS-CoV and MERS-CoV viruses that cause Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome, respectively.
The main source of infection with the SARS-CoV-2 virus is a sick person, including those in the incubation period of the disease. Currently, it is believed that the infection is transmitted by airborne droplets (when coughing, sneezing, talking), airborne and contact routes. At the same time, air, food products and household items contaminated with SARS-CoV-2 can be transmission factors.
The incubation period is 2 to 14 days.
In most people (up to 80% of cases), the infection is asymptomatic or mild, in 10-15% – in a moderate form, an extremely severe course is observed in 2-5% of those infected.
The disease, named COVID-19 and caused by the SARS-CoV-2 virus, is diagnosed based on clinical examination, epidemiological history and laboratory results.
The disease is characterized by the presence of clinical manifestations of an acute respiratory viral infection. The main symptoms are fever, dry cough or with a small amount of sputum, shortness of breath, myalgia and fatigue, a feeling of congestion in the chest. Diarrhea, nausea, and vomiting are possible early on with COVID-19. There are mild, moderate and severe forms of SARS-CoV-2 infection. The severe form of the disease occurs as pneumonia with acute respiratory failure, acute respiratory distress syndrome (ARDS), sepsis.
Real-time PCR testing is used for specific laboratory diagnosis confirming SARS-CoV-2 infection.
Analytical characteristics of the PCR test for “SARS-CoV-2 Coronavirus, determination of RNA, quality, in a swab from the mucosa of the nasopharynx and / or oropharynx”
Analytical sensitivity
1 × 10 3 copies/ml of original sample .
Analytical specificity
Cross reactions with viruses ( influenza A and B, parainfluenza, adenovirus infection, respiratory syncytial infection, metapneumovirus infection, rhinovirus infection and human coronavirus infection caused by HCoV-NL63, HCoV-OC43, HCoV-229E, HCoV-HKU1 ) and microorganisms ( Streptococcus pneumoniae , Haemophilus influenzae, Streptococcus pyogenes, Staphylococcus aureus ) was not found.
Pass the test for coronavirus COVID-19 in Samara
- INVITRO
- COVID-19
org/ListItem”> Tests- Screening program for office workers
- Household screening
- Cardiovascular risk assessment
- Antiphospholipid syndrome (APS) diagnosis
- COVID-1 9
- Assessment of liver function
- Diagnosis of kidney and genitourinary system
- Diagnosis of the gastrointestinal tract
- Diagnosis of connective tissue diseases
- Diagnosis of diabetes mellitus
- Diagnosis of anemia
- Oncology
- Diagnosis and management of osteoporosis therapy
- Biochemistry of blood
- Diagnosis of thyroid gland condition
900 71 Hospital profiles
- Healthy you – healthy country
- Gynecology, reproduction
- Healthy child: for children from 0 to 14 years
- Sexually transmitted infections (STIs)
- Weight problems
- VIP examinations
- Respiratory diseases
- Allergies
- Determination of trace elements in the body
- Beauty
- Vitamins
- Diets
- Laboratory tests before dieting
- Hormonal tests for men
- Depression
- Laboratory tests for medical references
900 71 Sports profiles
- Biochemical studies
- Glucose and metabolites of carbohydrate metabolism
- Proteins and amino acids
- Bile pigments and acids
- Lipids
- Enzymes
- Renal function markers
- Inorganic substances/electrolytes:
- Vitamins
9 0071 Proteins involved in iron metabolism
- Cardiospecific proteins
- Markers of inflammation
- Markers of bone metabolism and osteoporosis
- Determination of drugs and psychoactive substances
- Biogenic amines
- Specific proteins
- Biochemical studies
- Hormonal studies
- Laboratory assessment of the pituitary-adrenal system
- Laboratory assessment of the somatotropic function of the pituitary gland
- Laboratory assessment of thyroid function
- Parathyroid function assessment
- Pituitary gonadotropic hormones and prolactin
- Estrogens and progestins
- Assessment of androgenic function
- Non-steroidal regulatory factors of the sex glands
- Pregnancy monitoring, biochemical markers of fetal condition
- Laboratory assessment of pancreatic endocrine function and diagnosis of diabetes
- Biogenic amines
- Laboratory assessment of the renin-angiotensin-aldosterone system
- Factors involved in the regulation of appetite and fat metabolism
- Laboratory evaluation endocrine function of the gastrointestinal tract
- Laboratory assessment of hormonal regulation of erythropoiesis
- Laboratory evaluation of pineal gland function
- Healthy lifestyle tests
- Hematological tests
- Clinical blood test
- Immunohematological tests
- Coagulological tests (coagulus gram)
- Immunological studies
- Comprehensive immunological studies
- Lymphocytes, subpopulations
- Phagocytosis assessment
- Immunoglobulins
- Complement components
- Regulators and mediators of immunity
- Interferon status, assessment of sensitivity to immunotherapeutic drugs:
- Allergological studies
- IgE – allergen-specific (allergotests), mixtures, panels, total IgE.
- IgE – allergen-specific (allergotests), mixtures, panels, total IgE.
