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Frequently asked questions2022-10-18T17:21:11+02:00

FREQUENTLY ASKED QUESTIONS

Frequently asked questions about our tests

How much does it cost and where can I get a Cellular Immunity Test?2022-06-08T12:33:47+02:00

The price of the COVID Cellular Immunity Test (ELISPOT) for individuals is €199 per person. The price of the ELISA test from Monday to Friday is €55 and the post-vaccine and post-COVID IgG ELISA is €35 with a supplement of €5 plus weekends and holidays. The tests can be carried out in Madrid, in our clinic at Paseo del General Martínez Campos number 46.

*Macrophages, dendritic cells and NK cells, in addition to creating and presenting antigens, also synthesize activating cytokines of other T lymphocytes.

How long does it take to know the results? What does the test require?2022-06-08T12:37:46+02:00

The results are delivered on Fridays after 8:00 p.m. regardless of the day of the test. The results will be in English and Spanish.

To carry out the test, only an intravenous blood sample (4mL) is needed and it is advisable for the person undergoing the test to come hydrated, it being essential to have drunk plenty of water or other liquid before your appointment. The latter is essential for babies and minors.

It is not necessary for the person to come fasting.

Are your results reliable?2022-06-08T12:40:27+02:00

Totally. These tests are very specific.Moreover, the cytokines released in response to an antigen can be detected at the level of a single cell through the ELISPOT technique, so it is possible to calculate the frequency of T cells capable of recognizing the pathogen and, therefore, detecting it. whether or not there is cellular immunity.

Is it better to have an ELISA test or a Cellular Immunity test?2022-06-08T12:41:31+02:00

These tests are complementary because each one identifies a different type of immune response against SARS-CoV-2.

How is it different from the ELISA test?2022-06-08T12:44:36+02:00

The ELISA test identifies the antibodies, and the Cellular Immunity test detects the cytokines released by T Lymphocytes. Because antibodies eventually disappear from the body, an ELISA test can give a negative result if it is performed on a person who overcame the disease months ago. However, that same person may still have cellular immunity, which will be detectable using a Cellular Immunity test.

What is cellular immunity? And humoral immunity?2022-06-08T12:53:50+02:00

There are two types of immunity against pathogens in our body; the innate (natural) and the adaptive (acquired).

The innate response is the one that occurs quickly and nonspecifically. In addition, it does not increase with exposure to the pathogen. It is the first barrier in our body, among which are: physical barriers such as the skin or mucous membranes, chemical barriers such as the pH of fluids, lipids, biochemical barriers such as enzymes or acute phase proteins, and cellular barriers such as macrophages. , dendritic cells or NK cells (all of them are different types of lymphocytes), among others.

The adaptive response is the slowest, much more specific one, and it does increase with exposure to the pathogen. This response is mediated by T and B lymphocytes.

Within the adaptive immune response, two types can also be differentiated:

  • Humoral immunity acts against extracellular pathogens through B lymphocytes, which, upon encountering them, transform into antibody-producing plasma cells. Once the disease has passed, it is most likely that we will develop memory B lymphocytes and that the next time we come into contact with the virus, the response to it will be faster.
  • Cellular immunity is mainly specialized in fighting intracellular pathogens (such as viruses). Macrophages, NK cells and dendritic cells* come into contact with the pathogen, produce antigens and present them to other classes of T lymphocytes, mainly cytotoxic and helper cells. These helper T cells are responsible for activating other immune cells by secreting cytokines and more antigens.

As the disease passes, some T lymphocytes will have differentiated into memory T lymphocytes, which, like memory B lymphocytes, will manage a faster immune response the next time they come into contact with the pathogen.

What does a COVID-19 Immunity Test (ELISPOT) mean, what is it and what does it consist of?2022-06-08T12:57:20+02:00

The COVID Cellular Immunity Test is performed through the ELISPOT test. This test is based on enzyme-linked immunosorbent assay (ELISA) and designed for the study of the cellular immune response.

At Life Length we measure this cellular immune response by detecting two types of cytokines.

Cytokines are small proteins that are crucial for controlling the growth and activity of other cells of the immune system (T lymphocytes), causing the response to be amplified.

The two cytokines that we quantify in Life Length are:

  • Interferon-gamma (IFN-γ): is a cytokine that participates in multiple processes and at different points of activation of the immune system, which makes it essential in the response to pathogens, especially viruses. It is secreted mainly by activated T lymphocytes and Natural Killer (NK) cells.
  • Interleukin 2 (IL-2):this cytokine induces the proliferation and activation of other immune cells, launching an effective response against pathogens. In addition, it is essential in the differentiation of memory T lymphocytes, helping the body to respond quickly when it comes into contact with a certain antigen again. It is secreted by activated T lymphocytes, NK cells and dendritic cells.
How much does it cost and where can I do the rapid antigen test in Madrid?2022-08-08T08:44:29+02:00

The price of the antigen test for individuals is €39 per person. The price of the PCR test is €89 from Monday to Friday (supplement of €15+ on weekends and holidays) and the ELISA test, €55 from Monday to Friday. The combination of two tests carries a small discount of €10.

You and your family can take the tests in Madrid from Monday to Friday from 8:00 a.m. to 7:00 p.m. and on Saturdays and Sundays from 9:00 a.m. to 3:00 p.m., at our office at Calle Miguel Ángel 11, on the second floor. And it is necessary to book an appointment.

Should I combine it with another test for COVID-19?2022-06-08T13:12:55+02:00

When a person decides to get tested, especially if they are asymptomatic, it is advisable to do both types of tests, the antigen test (or the PCR test) together with another serology test that detects antibodies, either the ELISA test or the rapid test of antibodies. The combination will tell us what phase of the disease we are in. In the first days after infection, the antigen test will be positive and the serology could be negative; later it will be the other way around: the serologies will be positive and the antigen test or the PCR test will be negative.

On the other hand, if the antigen test is negative but the person has clear symptoms of COVID-19, they should be contrasted with a PCR test immediately.

The negative result, is it valid to travel by plane?2022-06-08T13:14:48+02:00

The rapid antigen test is valid for travel to any country that accepts this type of test. At Life Length we deliver the results report in English and Spanish, automatically, including the extraction date as required by some countries to cross their borders. See here an example of the PCR test report.

How is the test done and when should it be done?2022-06-08T13:18:37+02:00

To carry out this immunochromatographic test, it is necessary to collect a nasopharyngeal sample, that is, from the nasal portion of the pharynx, with a sterile rayon swab, which will be later analyzed in the rapid detection kits for SARS-CoV- 2.

The Rapid Antigen Test is indicated for people with symptoms in the first days of evolution of COVID-19, and for those asymptomatic who have had recent direct contact with a person who has tested positive.

What are antigens?2022-06-08T13:20:30+02:00

Definition of antigen: “substance that triggers the formation of antibodies and can cause an immune response”.

An “antigen” is also defined as any molecule that penetrates our body and that the defense mechanisms identify as foreign or unknown. Therefore, in this definition the types of antigens include any element that is part of a pathogen (a virus, a bacterium, a fungus), or any toxin, allergen, etc.

These molecular structures found on the surface of viruses are recognized by the immune system which triggers the production of antibodies. Antigen tests, therefore, detect these structures that are part of the outer envelope of the virus, that is, the proteins of the virus. However, when we perform a PCR test we are detecting the presence of the genetic material of the SARS-CoV-2 virus, RNA in this case.

 

What is the sensitivity and specificity of your antigen test?2022-06-08T13:23:59+02:00

The sensitivity of our antigen tests is 87.25% and the specificity is 100%. The confidence intervals are: Sensitivity 79.2% – 93%; Specificity 97.2% – 100%. The test results are usually lower in asymptomatic people and, therefore, if in doubt, a PCR test should be performed.

Sensitivity is the ability of the antigen test to detect the disease and is calculated as the percentage of true positives over the total number of patients. For example, a sensitivity of 97% means that only 3 out of 100 samples have been diagnosed as negative (healthy people) when, in fact, they were from infected individuals (positive). This 3% indicates the percentage of so-called “false negatives”.

Specificity is the ability of the antigen test to detect healthy individuals and is calculated as the percentage of true negatives over the total number of healthy individuals. For example, a sensitivity of 98% means that only 2 out of 100 samples have been diagnosed as positive (infected) when, in fact, they were from healthy people (negative). This 2% indicates the percentage of so-called “false positives”.

Why have they taken so long to be offered in Spain?2022-06-09T10:50:46+02:00

The first antigen tests for COVID-19 that some American and European countries, including Spain, bought had a sensitivity of less than 30%, something completely unacceptable. The European and United States public health regulatory agencies became serious about regulating its distribution and only now can we have highly reliable antigen tests, with sensitivities and specificities greater than 90%. Although not all tests are equally reliable, at Life Length laboratories we have evaluated 13 different manufacturers before choosing the test we offer.

What are its advantages over the PCR test?2022-06-09T10:57:54+02:00

Speed: although we deliver the results of the PCR tests on the same day they are performed, undoubtedly the time to know the result of these tests is their greatest advantage. The results of the antigen tests are known after 15 minutes.

Simplicity: Antigen tests do not require expensive reagents, robots, or qualified technical personnel for their results and although they can be performed in the same place of patient care, the World Health Organization does not recommend that they be done in places where they do not comply with the necessary biosafety measures, both for the safety of the person performing the test and for the risk of contamination of the sample.

Price: they are notably cheaper than the PCR test, 99 euros compared to 45 euros for the antigen test. So it looks like they could be done more frequently than PCRs, and on a larger scale.

Are antigen tests really reliable?2022-06-09T12:17:06+02:00

Without reaching the reliability of the best test to detect COVID-19 so far with 99.9% reliability, the PCR test, our tests that detect the presence of antigens offer more than acceptable results. With 87.25% sensitivity and 100% specificity, our tests become almost as reliable as PCR, if they are performed during the first days of the onset of symptoms.

How much does it cost and where can I do an ELISA test?2022-06-09T12:13:55+02:00

The price of the ELISA test for individuals is 55 euros per person from Monday to Friday and €5 more on weekends and holidays, the price of PCR test is 110 euros (Monday to Friday, weekend or holiday supplement +€15) and the antigen test is 50 euros. The tests can be carried out in Madrid, in our clinic at Paseo del General Martínez Campos number 46.

 

Should I combine an ELISA test with a PCR test?2022-06-09T12:15:44+02:00

When a person decides to take a COVID-19 test, especially if they have recently been in contact with someone infected, it is advisable to carry out both types of tests, PCR and another serology test, either the ELISA test or the rapid test. The combination of these two types of tests will tell us what phase of the infection we are in: in the first 2 weeks after infection, the PCR test will be positive and the serology will be negative; later, it will be the other way around: the serologies will be positive and the PCR test negative.

How long does it take to know the results?2022-06-09T12:17:55+02:00

The results of the ELISA test are delivered on Fridays from 8:00 p.m. and will arrive by e-mail.

When do IgA, IgM and IgG antibodies appear and what do they indicate?2022-06-09T12:20:10+02:00

Immunoglobulins A (IgA) are the first to appear, 4-5 days after infection and are one of the body’s main antibodies and are found both in the mucous membranes of the respiratory tract and the digestive system and in saliva, in tears and breast milk.

Immunoglobulins M (IgM) are the following antibodies that our body makes to fight an infection, they are detected around 10-15 days and are found mainly in the blood and lymphatic fluid. A positive IgM against SARS-Cov-2 would indicate that we are probably going through the acute or central stage of the infection.

Immunoglobulins G (IgG) are the most frequent antibodies in our body, they are detectable after 15-20 days and are found in the blood and other fluids. They provide protection against bacterial and viral infections and take time to form after an infection or after receiving a vaccine. A positive in IgG against SARS-Cov-2 would indicate that we have completed the last stage of a viral infection and that we are in the resolution phase.

Are the results of the ELISA test reliable?2022-06-09T12:23:23+02:00

Very high percentages in these two metrics are mandatory to be able to trust their results. Our laboratory performs the most complete test, which quantifies and measures the 3 types of IgA, IgM and IgG antibodies, using S (spike) and N (nucleocapsid) protein antigens to improve the sensitivity, specificity and robustness of the assay.

What are the sensitivity and specificity of a test?2022-06-09T12:31:19+02:00

Sensitivity is the ability of the test to detect disease. It is calculated as the percentage of true positives over the total number of patients. For example, a sensitivity of 98% means that only 2 out of 100 samples have been diagnosed as negative (healthy) when, in fact, they were from infected individuals (positive). That 2% indicates the percentage of so-called false negatives.

Specificity is the ability of the test to detect healthy individuals. It is calculated as the percentage of true negatives over the total number of healthy individuals. For example, a sensitivity of 99% means that only 1 in 100 samples have been diagnosed as positive (infected) when, in fact, they were from healthy individuals (negative). That 1% indicates the percentage of so-called false positives.

What is a quantitative type antibody test?2022-06-09T12:31:56+02:00

In addition to knowing if we have (or not) IgA, IgM and IgG antibodies against SARS-CoV-2, this test will measure the amount of antibodies in the blood sample, also known as the count.

What are antibodies and which ones are looked for in this test?2022-06-09T12:33:09+02:00

Antibodies, also known as immunoglobulins and abbreviated with the acronym “Ig”, are glycoproteins of the gamma globulin type or better said, and to understand us, antibodies are defense proteins that the immune system manufactures and are used to identify and combat foreign elements such as such as viruses, bacteria and toxins.

IgA and IgM appear first, but it is the presence of IgG antibodies against the virus, which appear approximately from day 15 from the start of the infection, which provide probable immunity. Although it is currently unknown for how long, it is usual that over the months or years, depending on the case, the IgG antibodies weaken until they disappear or cease to be effective.

What does an ELISA test mean, what is it and what does it consist of?2022-06-09T12:35:34+02:00

From the acronym Enzyme Linked Immuno Sorbent Assay, which means “enzyme-linked immunosorbent assay”,the ELISA test is a quantitative test that indicates the amount of antibodies, or immunoglobulins, that we have in the blood against a virus. In this case, against the SARS-CoV-2 coronavirus. This laboratory test is also one of the most used to detect patients who have been infected with HIV.

The test only consists of a small blood draw (4 milliliters) and it is not necessary to come on an empty stomach.

 

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