Gianni Rezza (Ansa)
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09 January 2021 Signed by the Director of Prevention of the Ministry of Health, Gianni Rezza, the circular "Update of the definition of the COVID-19 case and testing strategies" which underlines how the latest generation antigenic tests "seem to show comparable results to the tests of RT- PCR "(molecular tests) especially if used within the first week of infection, and on the basis of the data currently available, they appear to be a valid alternative to RT-PCR.
If the clinical conditions of the patient show discrepancies with the latest generation test, the RT-PCR remains the gold standard for the confirmation of Covid-19 ".
The circular emphasizes that "if it is necessary to adopt extremely quickly public health measures, the use of rapid antigen tests in individuals with symptoms compatible with COVID-19 in the following contexts: high prevalence situations, to test possible cases / probable; outbreaks confirmed by RT-PCR, to test symptomatic contacts,
facilitate early detection of further cases as part of contact tracing and outbreak investigation; closed communities (prisons, reception centers, etc.) and work environments to test symptomatic people when a case has already been confirmed with RT-PCR; in health and social care / socio-sanitary contexts, or for the triage of symptomatic patients / residents at the time of access to the facility or for early diagnosis in symptomatic operators ".
"The reading times of the exam are short, but the sensitivity and specificity of the first and second generation tests tend to be lower than those of the molecular test and vary significantly depending on the time of sampling - the circular clarifies -. cases in which latest generation rapid antigenic assays or molecular tests in RT-PCR are not available, or response times are excessive, precluding their clinical and / or public health usefulness, the use of rapid antigenic tests that have the following minimum performance requirements: = 80% sensitivity and = 97% specificity ".
"The rapid antigen test (preferably fluorescent reading antigen tests or even better tests based on immunofluorescence with microfluidic reading) should be performed as soon as possible and in any case within five days from the onset of symptoms. In case of a negative result, the test must be repeated with RT-PCR method or with a second rapid antigen test after 2-4 days. Even after a first negative result and waiting for the second test, the measures provided for the duration and termination of isolation and quarantine ".