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Safety and Efficacy of Spray Intranasal Live Attenuated Influenza Vaccine: Systematic Review and Meta-Analysis.

ABSTRACT: Although influenza is a major public health concern, little is known about the use of spray live attenuated influenza vaccine (LAIV) among adults. For this reason, we conducted a systematic review and meta-analysis to investigate the efficacy and safety of LAIV, especially in adults with/without clinical conditions and children <2 years, with the final aim of possibly extending the clinical indications. PubMed/MEDLINE and Scopus were the two databases consulted through February 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. A critical appraisal was conducted. Analyses were performed by using ProMeta3 software. Twenty-two studies were included, showing that LAIV was associated with a higher probability of seroconversion when compared with a placebo and considering the A/H1N1 serotype (pooled OR = 2.26 (95% CI = 1.12-4.54), p-value = 0.022; based on 488 participants, without heterogeneity (I2 = 0.0%)). The meta-analysis also confirmed no significant association with systemic adverse events. Only rhinorrhea, nasal congestion, and sore throat were significantly associated with LAIV compared to the placebo. Despite limited available evidence, LAIV has proved to be a safe and effective flu vaccination, also due to its very low invasiveness, and our review's results can be considered a starting point for guiding future research and shaping forthcoming vaccination campaigns.

SUBMITTER: Perego G

PROVIDER: S-EPMC8472940 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe burden of influenza is increasingly recognised in Africa. The WHO recommends introducing influenza vaccination to high-risk groups: pregnant women, children <5 years, and the elderly. The Gambia currently has no influenza vaccination policy, but the NASIMMUNE study, a clinical trial of intranasal live attenuated influenza vaccines (LAIV) in young children provided an opportunity to study maternal attitudes towards LAIV for the first time in sub-Saharan Africa. We assess acceptability of LAIV, influenza knowledge and attitudes towards influenza vaccination in Gambian women. Additionally, we investigate predictors of willingness to receive influenza vaccine (intent) in pregnancy or seasonally for children <5.MethodsA cross-sectional survey was conducted in Gambian women at two urban health facilities. To assess LAIV acceptability, the exposure group (women whose children had received LAIV during the NASIMMUNE study) were compared to a control group (women whose children were not enrolled in the NASIMMUNE study). Demographics and health belief constructs were analysed as predictors of influenza knowledge and vaccine intent.FindingsThe exposure group (n = 150) expressed a higher preference for a nasal spray vaccine than an injection compared to the control group (n = 304) (93.3% vs. 34.9%, OR = 26.15, p < 0.0001). Those in the exposure group who preferred the nasal spray found it less distressing, safer or equally safe, and easier or equally easy to give (all p < 0.001) than injections. Influenza knowledge increased with education level (p = 0.006 for higher education vs. none), and varied between sites (p = 0.0005). Vaccine intent was >98%, but no association with influenza knowledge or difference between groups was observed. Various health belief constructs were associated with vaccine intent.ConclusionLAIV acceptability was higher in those with first-hand experience. Influenza vaccine intent was also high. Incorporation of seasonal LAIV into the childhood immunisation schedule in The Gambia would be feasible, particularly if combined with community-based health education.

Project description:IntroductionFluenz Tetra is an intranasal quadrivalent live attenuated influenza vaccine (QLAIV) and is recommended as the vaccine of choice for children in the 2014/2015 influenza season vaccination programme in the UK.ObjectiveThe primary objective of the study was to estimate the crude incidence rate of adverse events of interest (AEIs) following vaccination with the nasal QLAIV early in the 2014/2015 influenza season in children and adolescents in England.MethodsA pilot non-interventional cohort post-authorisation safety study (PASS) was conducted during the 2014/2015 influenza season in England. Vaccinees were recruited via the mass vaccination programme in England. Participant outcomes, validated by a healthcare professional (general practitioner) where appropriate, were captured through questionnaires (surface mail, telephone, e-questionnaire). Data analysis comprised descriptive statistics and calculation of event risks and incidence rates, stratified by age group and selected co-morbidities.ResultsThe final evaluable cohort consisted of 385 participants; the median (interquartile range) age was 4 (3-9) years with a range of 2-17 years, and 53.2 % were female. The most frequently reported AEI was nasal congestion (n = 167; 43.4 %; 312.3 per 1000 patient-weeks [95 % CI 267.3-364.8]). Further frequently reported AEIs were malaise (n = 87; 22.6 %; 123.4 per 1000 patient-weeks [95 % CI 98.9-154.1]) and cough (n = 80; 20.8 %; 118.5 per 1000 patient-weeks [95 % CI 95.1-147.8]). Five hypersensitivity-type reactions were reported, although on follow-up none were true hypersensitivity reactions or required hospitalisation. No serious adverse events (SAEs) were reported, with no hospitalisations or deaths. No significant change in reactogenicity or other apparent safety signals was detected as part of this study.ConclusionThe pilot study showed no significant change in reactogenicity or other apparent safety signals from the data collected. Continued enhanced surveillance of seasonal influenza vaccines will ensure their ongoing safety for the prevention of serious illness from seasonal influenza outbreaks.

Project description:Influenza A and B viruses cause significant morbidity and mortality worldwide. Current influenza vaccines are composed of three or four strains: A/H1N1, A/H3N2, and B (Victoria and Yamagata lineages). It is of great interest if immunization against both type A and B influenza viruses can be combined in a single vaccine strain, thus reducing the cost of vaccine production and the possibility of strain interference within the multicomponent vaccine. In the current study, we developed an experimental live cold-adapted influenza intertype reassortant (influenza A and B) vaccine on the live attenuated influenza vaccine (LAIV) A/Leningrad/134/17/57 backbone. Hemagglutinin (HA) and neuraminidase (NA) functional domains were inherited from the influenza B/Brisbane/60/2008 strain, whereas their packaging signals were substituted with appropriate fragments of influenza A virus genes. The recombinant A/B virus efficiently replicated in eggs and Madin-Darby Canine Kidney (MDCK) cells under optimal conditions, temperature-sensitive phenotype was maintained, and its antigenic properties matched the influenza B parental virus. The chimeric vaccine was attenuated in mice: after intranasal immunization, viral replication was seen only in nasal turbinates but not in the lungs. Immunological studies demonstrated the induction of IgG antibody responses against the influenza A and B virus, whereas hemagglutination inhibition (HAI) and neutralizing antibodies were detected only against the influenza B virus, resulting in significant protection of immunized animals against influenza B virus challenge. IFN?-secreting CD8 effector memory T cells (CD44+CD62L-) were detected in mouse splenocytes after stimulation with the specific influenza A peptide (NP366); however, the T-cell response was not sufficient to protect animals against infection with a high-dose mouse-adapted A/California/07/2009 (H1N1pdm09) virus, most probably due to the mismatch of key T-cell epitopes of the H1N1 virus and the LAIV backbone. Overall, generation of the chimeric A/B LAIV virus on a licensed LAIV backbone demonstrated prospects for the development of safe and efficacious vaccine candidates that afford combined protection against both type A and type B influenza viruses; however, further optimization of the T-cell epitope content within the LAIV backbone may be required.

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Safety and Efficacy of Spray Intranasal Live Attenuated Influenza Vaccine: Systematic Review and Meta-Analysis.

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