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So-called rapid swabs for coronavirus are being used more and more and are now also counted in official statistics. But are they really reliable enough to ensure that we do not have false negatives that can spread the contagion? Watch our video
Antigenic tests for the coronavirus are increasingly widespread, they are easy to handle, fast and inexpensive, they have many advantages and are also counted in official statistics, not only in Italy. Let’s talk about quick swabs, those that give the result in a few minutes and work more or less like a pregnancy test. But are they really reliable or do we trust tests that are not accurate? The doubt is legitimate and also arises from the experience of many. Last in time order and just to give a famous example is Elon Musk. Tesla’s inventor said he did 4 quick swabs on the same day, the same nurse, the same test, the same testing machine. Two were negative and two were positive. Are we risking sending people who have the virus because we check them with inaccurate tests?
Are there permits or can evidence be sold?
Understanding which antigen tests are used in our country is a complicated undertaking. There are dozens of tests on the market, but despite the numerous requests we made to the Ministry of Health to know what the authorization process is and if there is a list of authorized tests, we have never received a response. And the question that remains is: is there an authorization process or can some test that is on the market be used?
The rules in the US
In the United States the rules are very clear. The list of tests that have had an emergency clearance is posted and updated periodically on the Food and Drug Administration website. Only some laboratories can use them and it is specified that they can only be used in the presence of symptoms in the acute phase, that is, when it is assumed that the viral load is very high and therefore these tests, in general less sensitive than the molecular ones, can function. In any case, Americans recommend taking the positive and negative results with a grain of salt. And above all, do not use them for mass screening. A negative result given by an antigen test, in the USA, can never be considered definitive.
Negative rapid test requires no further investigation
The opposite is the case with us. A negative antigen test certifies the negativity of the subject. In case of a positive result, however, for confirmation it is necessary to repeat the swab with molecular analysis.
The proof of the announcement of the Commissioner for Emergency
Although there is no official list of tests used in our country, it is possible to trace the names of some of these through tenders. The Covid emergency commissioner has opened a contest for 5 million of these tests, but they have already bought at least twice as much, for more than 32 million euros. The manufacturer claims an accuracy of more than 90%, but a study published in the Journal of Clinical Virology certifies its reliability between 11% and 45%.
The same can be said for the tests listed in the announcement of Azienda Zero, the purchasing center for the Veneto region, which is buying tests for itself and 6 other regions for 148 million euros. Here the tests listed are dozens. For some there are scientific studies that show a lower reliability than declared. For others, there is no information other than that stated by the manufacturer.
The Veneto Trials
At Veneto they assure us that they have carried out all the necessary tests and that the sensitivity of antigenic agents is close to 100%. These are the data provided by Dr. Roberto Rigoli, director of the microbiology and virology unit of Treviso. Of 3,486 swabs tested in duplicate, that is, processed with antigen and molecular tests, 415 were positive in the molecular test and 413 in the antigen test. Only two have been lost. 3,049 were negative, 22 false positives. This data demonstrates a very high reliability of these pads, but you need to know how to use them. Rigoli specifies that samples must be analyzed on-site when they are taken. Just waiting for the time to bring them to the laboratory greatly reduces their effectiveness to the level of scientific studies published in the international medical literature.
Therefore, the problem persists. Can we be sure that this analysis timeliness is guaranteed throughout Italy or are we sending Covid patients because we test them incorrectly?
