Tuscany one step away from zero infections. But goodbye to flock immunity – Chronicle


Florence, 29 May 2020 – In Tuscany we are at 110 thousand test serological carried out on workers who have not stopped their activity during the lockdown period: about 250 thousand people. A start, because then the screening will be extended and everyone can already do it for free in the private laboratories that have joined the project Region, upon presentation of a request from the family doctor. Of the first 105,000 tests analyzed (50,647 performed with lancing device and 54,353 with venous sampling), only the 3.04% of the Tuscans tested positive for antibodies and therefore came into contact with the new coronavirus.

Data in hand, at least in Tuscany, it is not possible to hope forherd immunity to protect us from any new epidemic waves. But to prevent the improvement of the data of these days (also yesterday there have been only 4 new cases in our region and, unfortunately, two deaths) results in an easing of attention, and the virus returns to spread more massively, is it is necessary to insist with measures of social distancing and individual protection.

Out of 105 thousand tests, 1,639 revealed the presence of immunoglobulins G, which appear later and remain longer, indicating that the immune system has developed defenses against the virus. While 1,560 tested positive for immunoglobulins M, antibodies that appear earlier and indicate an ongoing infection. The majority who tested positive, 3,154 people, are in the 50 to 59 age group: 528 cases; followed by the 40-year-olds, with 372 cases, thirty-year-old with 204, twenty-year-old with 146. Between the ages of 10 and 19 22 children and youngsters were positive, 2 under the age of ten, 200 people tested positive between the ages of 60 and 69, between 70 and 79 the number drops to 88. There are also 26 over 80 and 6 over ninety. All HIV-positive people, i.e. 3,154 people, were subjected to diagnostic confirmation swab, highlighting the small number of 69 cases currently positive to the virus, that is 0.07%.

The figure of the currently positive has drastically decreased compared to three weeks ago, when the percentage was around 0.7% (it had also reached 1%), while among the 51,500 people tested in the health population the positive percentage of the swab was it was 1.1%. Data confirming that the virus is circulating less. Although few, the 69 cases identified with the serological test, confirm the strategic value of screening in support of epidemiological surveillance, especially in this phase 2.

Without screening, that asymptomatic population, positive at the time of the test, would not have been traced as it had no symptoms and would not have been isolated, together with close contacts, and could have continued to infect without its knowledge. At this time, the symptomatic ones represent more or less 80% of the coronavirus positive cases. A second important finding regards immunity, even if unfortunately both for the significant number of false positives (given by a high sensitivity of the tests which, on the other hand, produce very few false negatives), and for the uncertainty on the duration and protection of the antibodies produced, cannot have the value of a health passport. The test is also used to measure the spread of the virus, however if the antibodies were to disappear within a few months, especially in the asymptomatic, they would still not provide an exhaustive picture of how many people were infected during the epidemic.

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