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VENETO – The explanation is always the same: “The largest number of tampons in Italy are processed in Veneto: the infected are, therefore, necessarily many. Too bad – says the governor of the Venetians – that in accounting the ministry does not contemplate fast buffers. So – he concludes – apart from the first most infected region of the country ”. Very different is the opinion of the Dr. Maurizio Manno from Covesap, the Veneto Public Health Coordination.
Dr. Manno, President Zaia invites you to read the data with conscience …
Of course! Too bad that in doing so you insist on counting the molecular swabs and quick swabs together, making a serious evaluation error. From what we can understand from the complicated explanation given by Dr. Russo during a recent press conference, the Veneto Region, unique in the country, calculates the incidence, or the rate of new cases in a given period of time, providing a value only for the positives, but joining the results of two completely different tests.
Molecular and fast: we explain the difference in terms of reliability and efficiency
The molecular, or genetic, elaborated with a molecular biology technique known as pcr (polymerase chain reaction), which is in practice the exact recognition of the virus RNA; the rapid, or antigenic, based on the recognition of the virus surface protein by specific antibodies deliberately induced in laboratory animals.
You can’t put them together …
It would be like putting blood pressure and heart rate together: both tests refer to the heart but, as everyone knows, they have very different meanings.
But what difference is there in practice between molecular and fast?
Both the molecular test and the rapid test have a high specificity (ability to correctly identify virus negative subjects) exceeding 95%, but very different sensitivities (ability to correctly identify positive subjects) and this is what most matters for diagnostic purposes! While the molecular ones correctly identify more than 95% of the positives, the fast ones give as negatives, and therefore “lose” up to 30-40% of the positives or even more. The serious thing is that these false negatives go around believing that they are not contagious and instead they are.
So the 8% percentage also recently reaffirmed by President Zaia is not calculated correctly?
The percentage provided by President Zaia has two problems. The first is to put together different tests and the test is provided by the Veneto Region itself, which in a recent press release explained how positive numbers are calculated for a given day.
Come?
Of the total of 16,810 molecular swabs and 35,831 rapid swabs performed that day, the 3,320 positive cases were equal to 6.3%, joining molecular and rapid. The second problem is that this percentage is not comparable with those provided by the Ministry for Italy and for the other regions, which instead only consider molecular swabs.
So, do you think Covesap rapid tests should be abolished?
Absolutely not. Rapid tests are an important, rapid and inexpensive resource, if used correctly and in large quantities (for example, to photograph the spread of infection or to perform rapid mass detection or to assess the trend over time in a large population) but very dangerous if used for improper purposes, for example, diagnosis or screening of groups of subjects at high risk (health workers) or with greater fragility (elderly, children, immunosuppressed patients, etc.).
Zaia states that the classification in different risk zones (red, orange or yellow) is based on the objective evaluation of the Ministry of Health of 21 parameters. But then why is Veneto still classified in the yellow zone?
We have been asking for weeks to know the reasons for this unfortunate decision, denouncing the inexistence of the number of intensive care beds actually available in Veneto, one of the fundamental criteria, if not the main one, on which the assignment to the yellow zone is based. In fact, we believe that precisely this erroneous narrative by President Zaia – that we have defined the “yellow zone obsession” – has contributed in a very significant way to the spread of the infections that we experience today.
What do you think of the hypothesis that the current criticalities of the pandemic in Veneto are due to the so-called “English” variant?
The new variant is more transmissive than those known so far because it reproduces more quickly. Therefore, those who become infected, including the asymptomatic, carry a higher viral load in their mouth and nose and, therefore, are more contagious. It has probably already spread since the end of September, in the London area and in the south-east of England, but it could have happened months ago, in ways still unknown. However, nothing proves its supposed greater diffusion in Veneto than in other regions. In fact, the same variant was also found in Campania, Puglia and Abruzzo, almost always in patients who came from or had a relationship with the United Kingdom. Therefore, there is currently no scientific evidence that the spread of the infection in Veneto, out of control for several weeks, is attributable to the English variant.
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