Introduction: Human respiratory syncytial virus (RSV) is one of the most frequent causes of respiratory infections in children under five years of age, but its socio-economic impact and burden in primary care settings is still little studied. Methods: During the 2022/23 winter season, 55 pediatricians from five Italian regions participated in our community-based study. They collected a nasal swab for RSV molecular test from 650 patients under the age of 5 with Acute Respiratory Infections (ARIs) and performed a baseline questionnaire. The clinical and socio-economic burden of RSV disease in primary care was evaluated by two follow-up questionnaires completed by the parents of positive children, on day 14 and 30. Results: RSV laboratory-confirmed cases were 37.8% of the total recruited ARI cases, with RSV subtype B accounting for the majority (65.4%) of RSV-positive swabs. RSV-positive children were younger than RSV-negative ones (median 12.5 vs 16.5 months). The mean duration of symptoms for all children infected by RSV was 11.47 ± 6.27 days. We did not observe substantial differences in clinical severity between the two RSV subtypes, but RSV-A positive patients required more additional pediatric examinations than RSV-B cases. The socioeconomic impact of RSV infection was considerable, causing 53% of children to be absent from school, 46% of parents to lose working days and 25% of families to incur extra costs. Conclusions: Our findings describe a baseline of the RSV disease burden in primary care in Italy before the introduction of upcoming immunization strategies.

Background: Enhanced safety surveillance (ESS) of seasonal influenza vaccines is required by the European Medicines Agency (EMA). ESS is conducted during each Northern Hemisphere (NH) influenza season and aims to monitor the reactogenicity of influenza vaccines early in the season. A cell culture-based quadrivalent influenza vaccine (QIVc; Flucelvax® Tetra), which has an advantage of avoiding egg-adaptive mutations that may reduce vaccine effectiveness, has been available in Europe since the 2019/20 influenza season. The objective of this manuscript is to summarize ESS activity across three seasons for QIVc in all age groups. Methods: As per EMA guidelines, an enhanced passive safety surveillance (EPSS) approach was adopted. The EPSS envisages near-real-time surveillance of adverse events (AEs) that are reported spontaneously by vaccinees. The EPSS was conducted in primary care setting in Genoa (Italy) during the seasons 2019/20, 2020/21 and 2021/22. All AEs registered within the first 7 days following immunization were analyzed by season, type, age group and seriousness. Results: Over three seasons, a total of 3,603 QIVc exposures were recorded within EPSS. No safety signals were identified. The overall reporting rates of individual case safety reports (ICSRs) for the seasons 2019/20, 2020/21 and 2021/22 were 1.75% (18/1030), 0.48% (5/1032) and 0.40% (4/1001), respectively. The average number of AEs per ICSR was similar (range 3.3–3.8) across the three seasons. Most AEs were reactogenic in nature. The rate of AEs was similarly low in all age groups. Conclusions: These results support the favorable safety profile of QIVc in all indicated age groups.