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Given the increase in traffic speeds of coronavirus how do you know if you are infected or less? To date, there are four most popular methods. But it must be said immediately that many technological innovations are coming on this front that – when validated by health authorities, in some cases within a few weeks – will make some types of controls easy and fast.
In the last days Spallanzani of Rome took a photo of the currently available instruments ranging from the now very famous buffer in saliva or saliva tests. Here are your strengths and weaknesses.
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Hyssop
It is currently the most reliable test. It is taken with a very long cotton swab that is inserted into the nose and mouth. The material collected from the sticks (which are usually produced in Italian factories) is analyzed using chemical methods that amplify the genes of the virus. It is important to know that the swabs are analyzed only in specialized laboratories that are generally public (only some regions, including Lazio and Campania, have recently been opened to individuals) indicated by the health authorities. In some cases, these labs have very expensive machinery produced in particular in the Netherlands and Germany capable of processing thousands of swabs per day. The analysis takes an average of two to six hours.
Quick test
For this type of control, a sample collection very similar to that of the normal swab is expected. For the rapids, we do not look for the genes of the virus but its proteins (antigens). Response times are very short (about 15 minutes), but the sensitivity and specificity of this test are lower than that of the molecular test. This fast buffer was recently introduced for situations, for example, in airport passenger screening, where extremely short response time is important.
The blood (or immunological) test verifies the presence in the blood of the antibodies that our body’s immune system automatically produces to fight infection, their type (IgG, IgM, IgA) and possibly their quantity. Serology makes it clear whether you have been in contact with the virus, but cannot clarify whether or not the infection continues. This test requires a blood draw and is performed in specialized laboratories. Rapid serological tests are based on the same principle as the classical ones, but they are simplified. They are not always reliable either. Britain bought a few millions from a Chinese company in the spring, but then decided to destroy them because they were ineffective in practice.
Salivary test
Recently, tests that use saliva as a sample for analysis have been proposed. As for swabs, there are also molecular tests (which detect the presence of virus RNA in the sample) and antigenic tests for saliva tests (which detect viral proteins in the sample) and give only qualitative responses. that is, they only say if there are antibodies present in the body. They are especially useful in schools to select cases to submit to the classic swab.
Swab
Finally, in the hospital of Treviso, in Veneto, a type of rapid antigenic swab validated by the US health authorities is being tested. This swab, shorter than the cotton swab attached to the classic swab, can be manipulated directly by the patient (“It’s like picking the nose,” the doctors explain) and can be analyzed by a machine that costs only a thousand euros and gives answer In ten minutes. However, the Italian validation of this solution is still ongoing.
The 4 types
1 – The swab or molecular test
It is the most reliable for virus detection. It is done by taking a sample from the nasopharyngeal tract. Detects the presence of fragments of viral RNA (the genetic signature of the coronavirus), the analysis takes 2 to 6 hours.
2 – Rapid test with swab or antigen
It is used to search for the protein components of the virus. It takes much less time (about 15 minutes) than the molecular swab, but the reliability is lower, although it is considered sufficient for a first detection.
3 – The serological or immunological test
The serological (or immunological) test detects, by analyzing a venous sample, if it has come into contact with the virus, but not if there is an ongoing infection. There are also rapid serological tests, with highly variable reliability.
4 – The saliva test
It would be enough to spit a small amount of saliva into a container and goodbye to painful tampons. But saliva testing studies are still ongoing. In the United States, the Food and Drug Administration has approved the use of two saliva tests in emergency situations.
Last updated: 09:44
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