Prevalence of SARS-CoV-2 variants in Italy (ISS report n. 9)

Prevalence of SARS-CoV-2 variants of concern in Italy (adapted from the ninth ISS genomic surveillance report)

Published: 29 September 2021

The I-Co-Gen platform developed by the Italian National Institute of Health (ISS), and released in April 2021, is currently the most up to date and reliable system for the analysis and collection of SARS-CoV-2 genomic sequences in Italy. Since the release of I-Co-Gen the Italian National Institute of Health (ISS), supported by the Bruno Kessler Foundation and in collaboration with the Italian Ministry of Health, the Regional administrations and the Autonomous Provinces (PPAA), have started an ongoing and coordinated effort for the accurate mapping of the spread of SARS-CoV-2 variants in Italy. Results are released periodically in the form of brief reports (further details here).
This highlight provides a brief overview of the main results presented in the most recent report (data updated to August 24th 2021). Data from the previous report (July 20th 2021) are also included to facilitate the comparison.

Prevalence of SARS-CoV-2 variants in Italy (ISS report n. 9) — The table reports the prevalence of the four Variants of Concern (VOCs) of SARS-CoV-2 currently recognized by international health authorities: Alpha (B.1.1.7)^§, Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2). Additional information concerning the nomenclature and characteristics of these variants can be found here, in a recent publication by the World Health Organization (WHO).
Prevalence data are stratified by Region/Autonomous Province, the total number of genomic sequences included in the analysis is reported as well. Aggregated data are also reported to offer an overview of the current situation in Italy.
Matched data derived from the previous report are included to facilitate the comparison (July 20th 2021).
^§We report that, with the September 3rd 2021 update, ECDC (the most important European health authority) has removed the Alpha variant from the Variants of Concern list, since this variant shows a limited circulation in the continent and has a reduced impact on the efficacy of vaccination campaigns (see the following link). However, the WHO classification remains unchanged.

Based on the most recent ISS report (data updated to August 24th 2021) the Delta variant (lineage B.1.621 and derivatives) remains the prevailing variant of SARS-CoV-2 in Italy, with an estimated prevalence of 99.7% (regional range from 95.8% to 100%).
At the same time the prevalence of the Alpha variant (lineage B.1.1.7 and derivatives) is constantly decreasing: from 3.2% in the previous update (data updated to July 20th 2021) to 0.2% for interval of time included in the current ISS report(regional range from 0% to 2.1% - data updated to August 24th 2021). Moreover, it is important to underline that Alpha variant sequences were detected exclusively in the Sicily and Marche regions.
In the present update, a single isolate of the Beta variant was observed in the national territory (in the Marche region), so the estimated prevalence of this variant equals to 0% (regional range from 0% to 2.1%).
Finally, the Gamma variant was not detected in Italy.

To obtain more information concerning the data included in the report, the methods applied and the technical limitations of the survey, please refer to the complete report and the detailed analyses available on the ISS website.
Documentation about the most recent report is available at the following link (italian only):

Documentation about the previous report is available at the following links (italian only):

Source: ISS (prevalence data).