The impact of influenza viruses and influenza vaccination coverage in Italy in the 2021-2022 season: the InfluNet integrated surveillance system and the introduced news

Introduction: In Italy, the InfluNet integrated influenza surveillance system, during the 2021-2022 season, in the middle of the SARS-CoV-2 pandemic, was adequately modified and strengthened to support the monitoring of the spread of the SARS-CoV-2 virus. The present work aims to describe the impact of the 2021-2022 flu season on the Italian population, also in the light of the changes introduced in the InfluNet surveillance system. For a complete assessment of the impact of influenza viruses, the influenza vaccination coverage achieved during the season was also evaluated. Materials and methods: InfluNet is based on a network of sentinel physicians made up of general practitioners and pediatricians, recruited by the Italian Regions, who report cases of Influenza Like Illness (ILI) observed among their patients. Sentinel physicians (sentinel flow) and other doctors working in hospitals (hospital flow) also collaborate in the collection of biological samples for the identification of circulating viruses. To evaluate the impact of ILI on the Italian population, overall incidence (per 1,000 assisted) was calculated, as well as stratified by age group. Furthermore, vaccination coverage (%) in the total Italian population and by age group were also calculated. Results: The 2021-2022 season was characterized by limited circulation of flu viruses. At the end of December 2021, the incidence of ILI reached an initial peak of 5.16 cases per 1,000 assisted. A second peak was identified, also very contained, at the end of March 2022, equal to 5.25 cases per 1,000 assisted. Virological surveillance made it possible to characterize the two waves: the first was mainly supported by the circulation of respiratory syncytial virus, especially in children under five years of age, while the second wave was characterized by the circulation of influenza viruses. 14.4% of clinical samples analyzed by InfluNet network laboratories were found to be positive for influenza viruses. Among the positive samples, 82.9% belonged to the A(H3N2) virus and 29.3% tested positive for SARS-CoV-2. Vaccination coverage in the 2021-2022 season, which decreased in all age groups, was 20.5% in the general population and 58.1% in the elderly population. Discussion and conclusions: In Italy, the 2021-2022 season marked the return of the circulation of influenza viruses after the start of the COVID-19 pandemic, though in a moderate intensity. The InfluNet surveillance system is turning into a respiratory virus monitoring system and has made it possible, this season, to characterize the trend of ILI and to attribute the increase in cases to the various respiratory viruses. Vaccination coverage decreased compared to the previous season. The adoption of preventive measures in recent seasons has profoundly changed the epidemiology of ILI and respiratory viruses in terms of intensity and seasonality. The accumulation of susceptible population, especially in the pediatric age groups, has partly allowed a greater circulation of respiratory viruses in the 2021-2022 season and will also presumably allow it in future seasons. It is therefore increasingly important to vaccinate against flu to reduce serious complications and deaths, especially in the fragile population.

Differences in the incidence and clinical outcomes of SARS-CoV-2 infection between Italian and non-Italian nationals using routine data.

OBJECTIVES: This study was to compare the incidence and clinical outcomes of SARS-CoV-2 infection between Italian and non-Italian nationals. STUDY DESIGN: We retrospectively analysed data from the COVID-19 Italian integrated surveillance system (14 September 2020 to 17 October 2021). METHODS: We used multivariable Cox proportional hazards models to estimate the hazard ratio (HR) of infection and, among cases, the HRs of death, hospitalisation and subsequent admission to intensive care unit in non-Italian nationals relative to Italian nationals. Estimates were adjusted for differences in sociodemographic characteristics and in the week and region of diagnosis. RESULTS: Of 4,111,067 notified cases, 336,265 (8.2%) were non-Italian nationals. Compared with Italian nationals, non-Italians showed a lower incidence of SARS-CoV-2 infection (HR = 0.81, 95% confidence interval [CI]: 0.80-0.81). However, once diagnosed, they were more likely to be hospitalised (HR = 1.90, 95% CI: 1.87-1.92) and then admitted to intensive care unit (HR = 1.08, 95% CI: 1.04-1.13), with differences larger in those coming from countries with a lower human development index. Compared with Italian cases, an increased rate of death was observed in non-Italian cases from low-human development index countries (HR = 1.41, 95% CI: 1.23-1.62). The HRs of SARS-CoV-2 infection and severe outcomes slightly increased after the start of the vaccination campaign. CONCLUSIONS: Underdiagnosis and delayed diagnosis in non-Italian nationals could explain their lower incidence compared with Italians and, among cases, their higher probability to present clinical conditions leading to worse outcomes. Facilitating early access to vaccination, diagnosis and treatment would improve the control of SARS-CoV-2 transmission and health outcomes in this vulnerable group.

Salivary molecular tests for the diagnosis of SARS-CoV-2 infection: an experimental monitoring approach in Italian schools throughout the 2021-2022 school year

Introduction: The widespread of SARS-CoV-2 infection has raised concerns about the potential role of schools in community transmission. In Italy, a national screening test strategy was implemented throughout the 2021-2022 school year to monitor virus circulation in schools. Materials and methods The National Plan for Monitoring the circulation of SARS-CoV-2 virus in primary and secondary schools aims at testing students attending a sample of primary and secondary schools in each Italian Region, by means of molecular salivary testing, every two weeks. We report preliminary data for the period 13/9/2021-13/2/2022 comparing them with the trend of the incidence rate in the Italian population aged 6-13 years. Results A total of 486,206 students from across the country were invited for the screening 273,738 (55.3%) underwent the test and 1086 (0.40%) came back positive. The highest participation rate (> 60%) was recorded on January 2022. Incidence rate was low (< 5 x 10,000 students tested) between September and December 2021, it increased steadily on January 2022 (20.8 x 10,000) and it began to slowly decrease on February 2022. A similar trend was recorded in general population. Of note, a national average of 10% of tests performed on saliva gave indeterminate results. Discussion and conclusions The heterogeneous adherence of Regions to the Plan, the low testing acceptance by students and the high rate of indeterminate results suggest that saliva sampling should be considered carefully when planning a screening campaign in schools. Screening tests in schools emerged as a useful strategy in detecting and contrasting the spread of SARS-CoV-2, but more research is needed on the determinants of student participation and saliva sampling methods.

Temporin G, an amphibian antimicrobial peptide against influenza and parainfluenza respiratory viruses: Insights into biological activity and mechanism of action.

Treatment of respiratory viral infections remains a global health concern, mainly due to the inefficacy of available drugs. Therefore, the discovery of novel antiviral compounds is needed; in this context, antimicrobial peptides (AMPs) like temporins hold great promise. Here, we discovered that the harmless temporin G (TG) significantly inhibited the early life-cycle phases of influenza virus. The in vitro hemagglutinating test revealed the existence of TG interaction with the viral hemagglutinin (HA) protein. Furthermore, the hemolysis inhibition assay and the molecular docking studies confirmed a TG/HA complex formation at the level of the conserved hydrophobic stem groove of HA. Remarkably, these findings highlight the ability of TG to block the conformational rearrangements of HA2 subunit, which are essential for the viral envelope fusion with intracellular endocytic vesicles, thereby neutralizing the virus entry into the host cell. In comparison, in the case of parainfluenza virus, which penetrates host cells upon a membrane-fusion process, addition of TG to infected cells provoked ~1.2 log reduction of viral titer released in the supernatant. Nevertheless, at the same condition, an immunofluorescent assay showed that the expression of viral hemagglutinin/neuraminidase protein was not significantly reduced. This suggested a peptide-mediated block of some late steps of viral replication and therefore the impairment of the extracellular release of viral particles. Overall, our results are the first demonstration of the ability of an AMP to interfere with the replication of respiratory viruses with a different mechanism of cell entry and will open a new avenue for the development of novel therapeutic approaches against a large variety of respiratory viruses, including the recent SARS-CoV2.