Multicenter epidemiological investigation and genetic characterization of respiratory syncytial virus and metapneumovirus infections in the pre-pandemic 2018-2019 season in northern and central Italy

A Model-Based Estimation of RSV-Attributable Incidence of Hospitalizations and Deaths in Italy Between 2015 and 2019

INTRODUCTION

Respiratory syncytial virus (RSV) incidence is known to be underestimated in adults due to its infrequent diagnostic testing and lower sensitivity of single nasal/nasopharyngeal swab PCR testing outside of the early childhood period. RSV can trigger acute cardiac events as well as cause respiratory disease. Consequently, we used a model-based study to estimate RSV-attributable hospitalization and mortality incidence among adults in Italy between 2015 and 2019.

METHODS

Through a database predisposed by CREA Sanità, by extracting monthly data from the Italian hospitalization collection data of the Ministry of Health and the Italian National Institute of Statistics (ISTAT) data (mortality), we estimated yearly RSV-attributable incidence of events for different cardiorespiratory outcomes. We used a quasi-Poisson regression model, which accounted for periodic and aperiodic time trends and viral activity proxies.

RESULTS

The yearly RSV-attributable cardiorespiratory hospitalization incidence increased with age and was highest among adults aged ≥ 75 years (1064-1527 cases per 100,000 person-years). Similarly, the RSV-attributable cardiorespiratory mortality rate was highest among persons aged ≥ 75 years (59-85 deaths per 100,000 person-years). Incidence rates for RSV-attributable hospitalizations and RSV-attributable mortality were on average 2-3 times higher for cardiorespiratory than respiratory disease alone. Incidence rate based on RSV-specific ICD codes only were 405-1729 times lower than modeled estimates accounting for untested events.

CONCLUSION

RSV causes a substantial disease burden among adults in Italy and contributes to both respiratory and cardiovascular conditions. Our results emphasize the need for effective RSV prevention strategies, particularly among older adults.

Circulation and Seasonality of Respiratory Viruses in Hospitalized Patients during Five Consecutive Years (2019-2023) in Perugia, Italy

The emergence of SARS-CoV-2 and the non-pharmacological interventions adopted to counter its spread appear to have led to changes in the normal circulation and seasonality of respiratory viruses. Our study aims to investigate changes related to the circulation of respiratory viruses, not SARS-CoV-2, among hospitalized patients in Perugia, Central Italy, between 2019 and 2023. The samples were collected from individuals who went to the emergency room (ER) or were hospitalized and analyzed using a molecular multiplex test. The results underline that non-pharmaceutical interventions altered the typical seasonal circulation patterns of different respiratory viruses. Those mostly affected were enveloped viruses like influenza viruses that disappeared in 2021; the least impact was recorded for Rhinovirus, which was detected during the pandemic period, maintaining the same seasonality observed in the pre-pandemic period although with a reduction in the number of positive samples. Our data underline the importance of the continuous monitoring of these viruses, especially to understand the timing with which prevention measures, not only non-pharmacological interventions but also the equipment of vaccine doses and monoclonal antibodies, should be adopted to reduce their circulation, particularly in the population at risk of developing severe forms of lower respiratory tract infection.

Presence and Significance of Multiple Respiratory Viral Infections in Children Admitted to a Tertiary Pediatric Hospital in Italy

Viral co-infections are frequently observed among children, but whether specific viral interactions enhance or diminish the severity of respiratory disease is still controversial. This study aimed to investigate the type of viral mono- and co-infections by also evaluating viral correlations in 3525 respiratory samples from 3525 pediatric in/outpatients screened by the Allplex Respiratory Panel Assays and with a Severe Acute Respiratory Syndrome-COronaVirus 2 (SARS-CoV-2) test available. Overall, viral co-infections were detected in 37.8% of patients and were more frequently observed in specimens from children with lower respiratory tract infections compared to those with upper respiratory tract infections (47.1% vs. 36.0%, p = 0.003). SARS-CoV-2 and influenza A were more commonly detected in mono-infections, whereas human bocavirus showed the highest co-infection rate (87.8% in co-infection). After analyzing viral pairings using Spearman's correlation test, it was noted that SARS-CoV-2 was negatively associated with all other respiratory viruses, whereas a markedly significant positive correlation (p < 0.001) was observed for five viral pairings (involving adenovirus/human bocavirus/human enterovirus/metapneumoviruses/rhinovirus). The correlation between co-infection and clinical outcome may be linked to the type of virus(es) involved in the co-infection rather than simple co-presence. Further studies dedicated to this important point are needed, since it has obvious implications from a diagnostic and clinical point of view.

Respiratory syncytial virus-associated hospitalizations among children: an Italian retrospective observational study

BACKGROUND

Respiratory syncytial virus (RSV), a single-stranded RNA virus, is a leading cause of hospitalization in infants, especially ≤ 2 months of life. In the light new immunization strategies adoption, we described epidemiological and clinical characteristics of RSV-associated hospitalizations in pediatric and neonatal intensive care units of the Policlinico Foggia Hospital, Apulia Region, Italy.

METHODS

Hospitalized children with a laboratory-confirmed RSV infection from 2011 to 2023 were retrospectively evaluated. Clinical information was collected from Hospital Discharge Registry in the period 2011-2020. The proportion of the hospitalization for acute respiratory infections (ARIs) associated to RSV was calculated and the hospitalization cost was analyzed by using the diagnosis-related group reimbursement rate. The anticipated impact of immunization either with monoclonal antibodies or maternal immunization on the number of hospitalizations was estimated. All analyses and quality assessment were performed using STATA/SE15.0.

RESULTS

A total of 1,005 RSV-cases were included in the study, of which 86.3% occurred between December-March. In the period 2011-2020, 832 RSV-cases were matched with the corresponding hospital admissions; 75.2% were aged < 1 year (49.6% 0-2 months). Bronchiolitis was the most frequent admission diagnosis occurring in 63.3% of patients; 25% of children were affected by a very severe RSV-disease. Younger age ≤ 2 months (OR:14.8, 95%CI:8.30-26.31, p = 0.000), higher length-of-hospital-stay (OR:1.01, 95%CI:1.0-1.02, p = 0.030) and history of prematurity (OR:4.4, 95%CI:1.57-12.11, p = 0.005) were associated with a higher disease severity. RSV caused 48.9% of ARIs among children < 1 year. The mean cost of an RSV-associated hospitalization was 3,036 euros/year, with the higher cost in the 0-2 months age group (4,225 euros/year). Immunization programs with nirsevimab could prevent 51.4 RSV hospitalizations/year and 18.1 very severe RSV disease/year in infants < 1 year of age. RSV vaccine could prevent 46.1 of hospitalizations/year caused by RSV within 180 days after birth.

CONCLUSIONS

Our study contributes to outlining the baseline profile of RSV-associated hospitalizations among Italian children by providing epidemiological/clinical/economic estimates. While awaiting new recommendations on immunization, healthcare-workers should persist in implementing public health measures and appropriate case management to control RSV seasonal epidemics. Strengthened laboratory RSV surveillance is needed to inform the implementation of the new immunization strategies.

Epidemiology and burden of respiratory syncytial virus in Italian adults: A systematic review and meta-analysis

OBJECTIVE

Respiratory syncytial virus (RSV) is a common respiratory pathogen not only in children, but also in adults. In view of a recent authorization of adult RSV vaccines in Italy, our research question was to quantify the epidemiology and burden of RSV in Italian adults.

METHODS

Observational studies on the epidemiology and clinical burden of laboratory-confirmed or record-coded RSV infection in Italian adults of any age were eligible. Studies with no separate data for Italian adults, modeling and other secondary publications were excluded. A literature search was performed in MEDLINE, Biological Abstracts, Global Health, Scopus and Web of Science on 22 November 2023. Critical appraisal was performed by means of a Joanna Briggs Institute checklist. Random-effects (RE) meta-analysis was performed to obtain pooled estimates and the observed heterogeneity was investigated by subgroup and meta-regression analyses. The protocol was prospectively registered (doi.org/10.17504/protocols.io.5qpvo32odv4o/v1).

RESULTS

Thirty-five studies were identified, most of which had at least one possible quality concern. RSV seasonal attack rates ranged from 0.8 ‰ in community-dwelling older adults to 10.9% in hematological outpatients. In the RE model, 4.5% (95% CI: 3.2-5.9%) of respiratory samples tested positive for RSV. This positivity prevalence was higher in older adults (4.4%) than in working-age adults (3.5%) and in outpatient (4.9%) than inpatient (2.9%) settings. According to the meta-regression, study location and sample size were also significant predictors of RSV detection frequency. The pooled estimate of in-hospital mortality was as high as 7.2% (95% CI: 4.7-10.3%). Data on other indicators of the diseases burden, such as complication and hospitalization rates, were unavailable.

CONCLUSION

RSV poses a measurable burden on Italian adults, especially those of older age and with some co-morbidities. However, several data on the natural history of RSV disease are missing and should be established by future large-scale studies.

Surveillance of Influenza and Other Airborne Transmission Viruses during the 2021/2022 Season in Hospitalized Subjects in Tuscany, Italy

Winter in the northern hemisphere is characterized by the circulation of influenza viruses, which cause seasonal epidemics, generally from October to April. Each influenza season has its own pattern, which differs from one year to the next in terms of the first influenza case notification, the period of highest incidence, and the predominant influenza virus subtypes. After the total absence of influenza viruses in the 2020/2021 season, cases of influenza were again recorded in the 2021/2022 season, although they remained below the seasonal average. Moreover, the co-circulation of the influenza virus and the SARS-CoV-2 pandemic virus was also reported. In the context of the DRIVE study, oropharyngeal swabs were collected from 129 Tuscan adults hospitalized for severe acute respiratory infection (SARI) and analyzed by means of real-time polymerase chain reaction (RT-PCR) for SARS-CoV-2 and 21 different airborne pathogens, including influenza viruses. In total, 55 subjects tested positive for COVID-19, 9 tested positive for influenza, and 3 tested positive for both SARS-CoV-2 and the A/H3N2 influenza virus. The co-circulation of different viruses in the population requires strengthened surveillance that is no longer restricted to the winter months. Indeed, constant, year-long monitoring of the trends of these viruses is needed, especially in at-risk groups and elderly people.