SARS-Cov-2 infection symptoms are often similar to those of many other viral infections in childhood: the infection commonly proceeds in a paucisymptomatic or in a completely asymptomatic way(1, 2).
Starting from the first phase of the pandemic (February / March 2020), protective devices, spacing, contact tracing (CT )were considered useful and necessary to reduce the spread of SARS-Cov-2 infection ; from the end of the year 2020 is available the vaccination against SARS-Cov-2 infection, now also for children over 5 years of age .
In Italy, the alert status for the presence of SARS-Cov-2 infection was officially declared on January 31, 2020 (3). On February 23, 2020, at the same time with the creation of the first "red zone" in Italy (Codogno), schools were also closed in the Piacenza district, which borders the "red zone" (4).
Italy began a full lockdown on March 8, 2020 (5).
Piacenza district recorded one of the highest cumulative mortality rates (> 3 deaths per thousand inhabitants) in Italy in the first phase of the pandemic(6).
Unfortunately, despite the Chinese experience, the speed of spread of the infection in our geographical area, the severity and number of cases have catch unprepared the Public Hygiene Services (PHS) in the first phase of the pandemic between February and May 2020.
Due to the low impact of the infection in pediatric age, most of the available resources were directed elsewhere: In this emergency situation, most children with suspected SARS-Cov-2 infection were not tested due to the lack of nasal swabs and mild symptoms, which rarely required hospitalization therefore it was not even possible to apply contact tracing due to lack of swabs, health personnel to perform swabs and to carry out tests in the laboratory.. In the first phase of the pandemic, primary care pediatricians (PCP) could report suspected cases to the PHS to carry out the molecular swab if epidemiological (close contact with a positive subject or from a red zone) and clinical (7) criteria were present simultaneously. However, in a series of 175 suspected cases reported at that time by 13 PCP (unpublished data) only 46 underwent molecular swabs almost always many days after reporting and only 2 were positive The symptoms prevalent in this series (mean age 6 years) were fever, cough, gastroenterological disturbances, headache, dermatological manifestations.
For epidemiological purpose, one month after the end of lockdown (June 2020), National Health Service underwent to sierological test of Covid-19 antibodies (CMIA Abbott) about half of these children : 50% of them had significant IgG anti-Covid-19 levels. From this survay, which also involved the adult population, it was estimated that the number of subjects affected by SARS-Cov-2 infection in the first wave was 6 times higher than that diagnosed by nose-pharingeal molecolar test (8).
From May 2020, the presence of clinical criteria was considered sufficient to report a suspected case of SARS-Cov-2 infection to the PHS. (9) .Reopening of school activities in September 2020 and before the beginning of a second pandemic wave (which then occurred from October 2020) the PHS has scheduled the execution of the CT whenever there is a positive case with the aim to stem the effects of the spread of the virus. The purpose of this work is to quantify how effective the CT activity is in identifying SARS-Cov-2 positive pediatric subjects compared to the only reporting of suspected cases based of clinical elements. This type of survey was possible because the Italian National Health Service provides that children up to the age of 14 are followed by PCP and in our area about 96% of children benefit from this type of assistance.