ISS, July 30th 2021
In Italy, as at 20 July, the prevalence of the so-called 'Delta variant' of the SARS-CoV-2 virus was 94.8%, a sharp increase compared to the survey of 22 June, with values of individual Regions ranging between 80% and 100%. On the same date, the 'Alpha' variant had a prevalence of 3.2% (range between 0 and 14.7%), while the prevalence of the 'Brazilian' variant was 1.4% (0-16,7%). These figures are provided by the new flash survey carried out by the Istituto Superiore di Sanità – ISS (Italian National Institute of Health) and the Ministry of Health together with the regional laboratories and the Bruno Kessler Foundation. The flash survey integrates routine monitoring activities, and therefore does not contain all the cases of variants detected, but only those recorded on the day taken into consideration.
"The rapid spread of the Delta variant, which has now become predominant, was expected and is consistent with the European data, and it needs to be monitored with great attention”, said ISS president, Silvio Brusaferro. “It is essential to continue the systematic tracking of cases to identify the outbreaks and complete the vaccination campaign as quickly as possible, since the best protection is ensured only by vaccines".
For the flash survey, the laboratories of the Regions and Autonomous Provinces were asked to select subsamples of positive cases and to sequence the genome of the virus. The sample requested was chosen by the Regions / Autonomous Provinces at random from among the positive samples of the selected day, ensuring geographical coverage and, if possible, representation of different age groups. In total, 21 Regions / Autonomous Provinces and a total of 123 laboratories participated in the survey and 1,325 samples were sequenced.
Here are the main observations that emerged:
· the diffusion of variants with greater transmissibility may have a significant impact. The Delta variant (B.1.167.2) is to be considered predominant in this flash survey, having replaced the Alpha variant for the first time (B.1.1.7). This fact, which however was expected, is in line with what has been observed in other European countries. The Delta variant is, in fact, characterized by a
transmissibility from 40 to 60% greater than the Alpha variant, and is associated with a relatively higher risk of infection in unvaccinated or partially vaccinated individuals;
· there was an increase, albeit extremely limited, in the Beta variant (B.1.351), which is more characterized by partial immune evasion, while the prevalence of the Gamma variant (P.1) decreased dramatically throughout the Country;
· in the current European and national scenario, characterized by the circulation of different variants of the SARS-CoV-2 virus, it is necessary to continue to monitor the diffusion of the variants with great attention - in particular, those with greater transmissibility or with mutations that enhance their ability to evade the host’s immune response - in accordance with national and international recommendations and with the ministerial indications;
· moreover, in order to contain and mitigate their impact, it is important to maintain the incidence at values that allow for the systematic tracking of positive cases and, as far as possible, promote the massive sequencing of the SARS-CoV-2 variants for early detection, for curbing their evolution and for avoiding their rapid spread throughout our Country. To this end, it is absolutely important to test, trace and isolate or quarantine suspected cases and their contacts.
