COVID-19 TESTS AT GLANCE

WHICH TESTS ARE AVAILABLE?

There are now many different COVID-19 tests, so that it can be difficult for the patient to find their way around the always larger range. We explain the various test methods so you can find the right test for you without spending too much money or even falling for unreliable and dubious offers.

Detection of an active vs. previous infection

The most important difference is between the detection of an active and a previous infection.

Active infection can be symptomatic, i.e. the patient has symptoms of COVID-19 disease, or asymptomatic, i.e. the patient does not realize that he has contracted the virus. In either case, the infected person can spread the virus to other people.

We talk about the proof of a previous infection when we can show by detection of antibodies that a person has come into contact with the virus in the past. As explained above, the patient may have gone through the disease, or infection passed unnoticed. The person is concerned no longer contagious at this point. Depending on the quantity of antibodies, there is a high probability that the patient will be immune to re-infection.

Sample material

There are tests that need a nose or throat swab (PCR tests, rapid antigen tests) and tests that require a blood sample (venous blood sampling or capillary blood from the fingertip).

Time

Perhaps what patients are most interested in, is how long they have to wait for the test result. There are tests in which the sample has to be processed in a laboratory (PCR tests, antibody tests) and which therefore require at least 24 hours (in reality 2-4 days can elapse until the results are reported), and the, so called, rapid tests (antigen or antibody tests) that give a result within 15-30 minutes. The validity of the new rapid tests in the meantime is very high.

SWAB AND ANTIBODY TEST

Nasal or throat swab/ PCR test

What is investigated?
Evidence of an acute (contagious) infection with or without symptoms.
Which method is used?
A biomolecular method, the polymerase chain reaction (PCR). The swab contains genetic material of the virus (RNA), which will be detected.
How is it tested?
A swab from the nose or the throat is taken with a cotton swab.
How long do I have to wait for the result?
On average 1 – 4 days.
When can the test be performed?
The test can be performed at any time if an infection is suspected. The test is most reliable in the first week of infection.
What does a positive test result mean?
A positive test result means that you have an active infection and can spread the virus. It does not automatically mean that you will get the COVID-19 disease and develop symptoms. A positive result is no reason for being worried. Most of the infected persons are asymptomatic or have a light course of disease.
What does a negative result mean?
A negative result makes an active infection very unlikely but cannot exclude it. Even if it is unlikely that you can spread the virus you should be careful.
Where can I take the test in Florence?
People with an Italian health insurance card (tessera sanitaria) can ask their family doctor (medico di base).
Foreign guests without access to the public health system can take the test with costs in one of the diagnostic institutes in Florence. The swab is only possible by appointment. Depending on the demand, you may have to wait several days for it. If you wish, we can help you with the appointment free of charge.

Antibody Test

What is investigated?
Whether a person has dad contact with the virus in the past.
Which method is used?
Antibodies are detected in the blood.
How is it tested?
A blood sample is taken.
How long do I have to wait for the result?
On average 1-4 days.
When can the test be performed?
Antibodies are formed from the second week after infection. However, it can take several weeks for a person to develop sufficient antibodies that they can be detected in the blood. Every patient develops a different quantity of antibodies.
How is the reliability of the test?
It depends on how long ago a possible infection took place and how many antibodies a person developed.
What does a positive test result mean?
A positive result means that you have had an infection with the virus in the past. Currently it is assumed that the person is then at least temporarily protected from re-infection by the antibodies. How long does the protection last has not yet been adequately cleared. However, it can be assumed that the immunity varies in individual patients.
What does a negative result mean?
A negative result means that there haven’t been detected antibodies. This doesn’t exclude a past infection but makes it improbably. The person actually is not protected against an infection. A negative result does not exclude an active infection. It says nothing about if the person can transmit the virus or not.
Where can I take the test in Florence?
People with an Italian health insurance card (tessera sanitaria) can ask their family doctor (medico di base).
Foreign guests without access to the public health system can take the test with costs in one of the diagnostic institutes in Florence. If you wish, we can help you with the appointment free of charge.

RAPID TESTS

The COVID-19 rapid test are all tests for immediate diagnosis. The sample material is elaborated immediately and the test result is available within a few minutes. Here, too, we roughly differentiate between direct virus detection by the antigen rapid test, in which parts of the virus (proteins) are detected directly from the nasal or throat swab, and indirect detection of antibodies against the virus from the capillary blood by the antibody rapid test.

Rapid Antigen Test (available soon at our doctor’s office)

What is investigated?
Proteins of the virus.
Which method is used?
A nasal or throat swab will be taken.
How long do I have to wait for the result?
Depending on the test between 15 and 30 minutes.
When can the test be performed?
The test can be performed at any moment in our doctor’s office or in a home visit, whenever you suspect an infection. If you have symptoms, if you have had contact with a person with COVID-19 or have been tested positive, or if you need a test for professional reasons or for a journey. The test is appropriate for the early diagnosis of an infection with coronavirus.
How is the reliability of the test?
The test we use is certified and recognized by international health authorities. The test is highly reliable. It is applicable for the early diagnosis of an infection with coronavirus.
What does a positive test result mean?
A positive test result means that you have an active infection and can spread the virus. It does not automatically mean that you will get the COVID-19 disease and develop symptoms. A positive result is no reason for being worried. Most of the infected persons are asymptomatic or have a light course of disease.
What does a negative result mean?
A negative result makes an active infection very unlikely but cannot exclude it. Even if it is unlikely that you can spread the virus you should be careful.
Where can I take the test in Florence?
You can take the rapid antigen test anytime at Dr. Silvia Kurpanik’s office. In case of suspicion of an infection with coronavirus or, if you are not able to come to the doctor’s office for other reasons, we will perform the test directly at your home. The costs are included in the consultation or home visit fee. If you need also a certification it costs additionally €15.

Rapid antibody test

What is investigated?
Antibodies to the virus in the blood.
Which method is used?
Some capillary blood will be taken from the fingertip (as with the blood sugar test).
How long do I have to wait for the result?
15 – 30 minutes.
What does a positive test result mean?
A positive result means that you have had an infection with the virus in the past. Currently it is assumed that the person is then at least temporarily protected from re-infection by the antibodies. How long does the protection last has not yet been adequately cleared. However, it can be assumed that the immunity varies in individual patients.
What does a negative result mean?
A negative result means that there haven’t been detected antibodies. This doesn’t exclude a past infection but makes it improbably. The person actually is not protected against an infection. A negative result does not exclude an active infection. It says nothing about if the person can transmit the virus or not.
Where can I take the test in Florence?
You can take the test anytime at Dr. Silvia Kurpanik’s office.

SARS-CoV-2 RAPID TESTS AND DISEASE STAGES

After an infection, Covid-19 disease goes through several typical stages. The various phases can be demonstrated throughout different results of the different tests.

Incubation period/ asymptomatic phase (day 0-5):
The so-called incubation period, the time that elapses from the infection to the appearance of the first symptoms (if the course is symptomatic), lasts between 3 and 5 days, depending on the patient. During this period, SARS-CoV-2 RNA and antigen slowly increase and usually cannot yet be detected by the rapid antigen test. At this point no antibodies can be detected either. Beside of the asymptomatic course, this period is responsible for the spread of the virus, because the patient does not know that he is infected but can transmit the virus to other people.

The first symptoms appear around the 5th day after infection. This phase lasts on average about 10 days (5th to 15th day). During this time, virus RNA and antigen increases significantly. Therefore it is also said that this is the best time to detect a current infection by a rapid antigen test. Asymptomatic courses can go unnoticed.

Around the 7th day after infection, the immune system begins to form antibodies against the virus. These are the immunoglobulins M (IgM). The IgM titer peaks around the 14th day and then falls down again. Normally IgMs are no longer detectable three weeks after infection.

Shortly after the peak of IgM, another type of antibodies, immunoglobulins G (IgG) begins to form. IgGs remain in the blood of the patient also after the infection or disease has been overcome and give him a longer lasting protection from re-infection. The formation of IgGs usually goes hand in hand with the patient’s recovery. At this point the patient is no longer infectious. But there are also patients who don’t produce a sufficient amount of antibodies to be detected by the tests. A negative antibody test cannot therefore say certainly that a person didn’t have been in contact with the virus. A positive IgG test, on the other hand says that the patient has a protection against a re-infection and that he cannot transmit the virus to other people.

The test result:

Positive rapid antigen test: Active SARS-CoV-2 infection with or without symptoms. The patient can transmit the virus to other people.

Rapid Antibody test:

IgM negative and IgG negative: An infection is unlikely but cannot be ruled out with certainty. The patient is not immune to the virus. Since it is not possible to make a statement about a current infection, it cannot be ruled out that the patient is contagious.
IgM positive and IgG negative: indicates the early stage of an infection. The patient is contagious.
IgM positive and IgG positive: Indicates the middle phase of the infection. The patient’s infectivity decreases and is usually very low at this point.
IgM negative and IgG positive: The patient has overcome the infection or disease and is no longer contagious. The IgG gives him a long term protection to the virus.
The test results should always be interpreted in the contest with the clinical picture of the patient.