Nasal spray live attenuated influenza vaccine: the first experience in Italy in children and adolescents during the 2020-21 season.

BACKGROUND: In Italy only recently, for the 2020-21 season, has the flu vaccination been extended to all children. A quadrivalent live attenuated influenza vaccine (qLAIV) was administered to children aged 2-17 years for the first time. We registered the number and severity of adverse reactions to (Fluenz Tetra™) and the factors influencing them, evaluated uniformity of access to care and assessed the degree of satisfaction with the vaccination of both parents and health care providers, in order to improve the 2021-22 vaccination program. METHODS: On vaccination day, a questionnaire was given out to collect information about the children and their parents. Between 1 and 3 months later, the parents were contacted to record any adverse reactions following (Fluenz Tetra™) and rate the degree of satisfaction. RESULTS: We received data of 3226 children from 2152 families. Adverse events were reported in 24.8% of children: 80.6% mild, 18.1% moderate and 1.3% significant. The most common were rhinitis (52.5%) and fever (24.4%). Statistical analysis performed with a multiple regression model, showed that children aged 2-5 years have an increased risk of adverse events compared to both 6-10 years old (aRR 1.7, 95% CI 1.5-1.9, p < 0. 001) and 11-17 years old (aRR 1.5, 95% CI 1-2.2, p = 0.051). Most families chose to vaccinate their children to protect them and because they were concerned about Covid19. The main channel through which parents became aware of a new flu vaccination was word-of-mouth (39.8%), which occurred mostly among parents of the same school group, followed by information from the child's doctor (30.6%), the Internet (26.9%), personal research (15%), newspapers (4%), telecommunications (7.5%) and other (2.6%). Most parents (83.3%) were very satisfied and intend to vaccinate their children with qLAIV again (83.8%). The majority of operators (93%) considered the experience as excellent and are willing to repeat it (94.6%). CONCLUSION: (Fluenz Tetra™) proved to be easy to administer and the degree of satisfaction was high among both health workers and parents. Considering its substantial safety profile especially in school-age children and adolescents, all these aspects make the nasal qLAIV optimal for widespread immunization. Schools offer the best setting to reach more families and physicians should be actively involved.

The virosomal adjuvanted influenza vaccine.

IMPORTANCE OF THE FIELD: The protection conferred by influenza vaccines varies for several reasons, for example the age or degree of immune depression of the recipient. All currently available seasonal influenza vaccines are safe and substantially effective in preventing influenza in healthy people. However, elderly people and patients with chronic diseases or immune system defects need a more effective vaccine to avoid serious risks from influenza and its complications. Research has been undertaken to improve the efficacy of vaccination. Recent research includes the use of new adjuvants or antigen-presenting strategies. AREAS COVERED IN THIS REVIEW: The virosomal adjuvanted subunit influenza vaccine has been studied in groups for whom vaccination is recommended. We describe virosomal technology, including production and mode of action, as well as the available efficacy, immunogenicity and safety data, with the aim of understanding the benefits of this vaccine's use. WHAT THE READER WILL GAIN: A review of published data on efficacy, immunogenicity and safety from sponsor- and investigator- driven studies, focusing on recent publications. TAKE HOME MESSAGE: The vaccine was generally very immunogenic and safe in all investigated populations. Its ability to induce protective antibody titers has been shown to exceed that of conventional influenza vaccines in elderly people and individuals with little or no prior exposure to the viral strains.