ABSTRACT
BACKGROUND: We report 2023/2024 season interim influenza vaccine effectiveness for three studies, namely, primary care in Great Britain, hospital settings in Scotland and hospital settings in England. METHODS: A test negative design was used to estimate vaccine effectiveness. RESULTS: Estimated vaccine effectiveness against all influenzas ranged from 63% (95% confidence interval 46 to 75%) to 65% (41 to 79%) among children aged 2-17, from 36% (20 to 49%) to 55% (43 to 65%) among adults 18-64 and from 40% (29 to 50%) to 55% (32 to 70%) among adults aged 65 and over. CONCLUSIONS: During a period of co-circulation of influenza A(H1N1)pdm09 and A(H3N2) in the United Kingdom, evidence for effectiveness of the influenza vaccine in both children and adults was found.
Subject(s)
Influenza A Virus, H1N1 Subtype , Influenza A Virus, H3N2 Subtype , Influenza Vaccines , Influenza, Human , Primary Health Care , Secondary Care , Humans , Influenza Vaccines/immunology , Influenza Vaccines/administration & dosage , Influenza, Human/prevention & control , Influenza, Human/epidemiology , Adolescent , Adult , Child , Child, Preschool , Middle Aged , Young Adult , United Kingdom , Aged , Influenza A Virus, H3N2 Subtype/immunology , Influenza A Virus, H3N2 Subtype/genetics , Male , Female , Influenza A Virus, H1N1 Subtype/immunology , Seasons , Vaccine Efficacy , Vaccination/statistics & numerical dataABSTRACT
BACKGROUND: The 2022/23 influenza season in the United Kingdom saw the return of influenza to prepandemic levels following two seasons with low influenza activity. The early season was dominated by A(H3N2), with cocirculation of A(H1N1), reaching a peak late December 2022, while influenza B circulated at low levels during the latter part of the season. From September to March 2022/23, influenza vaccines were offered, free of charge, to all aged 2-13 (and 14-15 in Scotland and Wales), adults up to 49 years of age with clinical risk conditions and adults aged 50 and above across the mainland United Kingdom. METHODS: End-of-season adjusted vaccine effectiveness (VE) estimates against sentinel primary-care attendance for influenza-like illness, where influenza infection was laboratory confirmed, were calculated using the test negative design, adjusting for potential confounders. METHODS: Results In the mainland United Kingdom, end-of-season VE against all laboratory-confirmed influenza for all those > 65 years of age, most of whom received adjuvanted quadrivalent vaccines, was 30% (95% CI: -6% to 54%). VE for those aged 18-64, who largely received cell-based vaccines, was 47% (95% CI: 37%-56%). Overall VE for 2-17 year olds, predominantly receiving live attenuated vaccines, was 66% (95% CI: 53%-76%). CONCLUSION: The paper provides evidence of moderate influenza VE in 2022/23.
Subject(s)
Influenza A Virus, H3N2 Subtype , Influenza B virus , Influenza Vaccines , Influenza, Human , Primary Health Care , Vaccine Efficacy , Humans , Influenza Vaccines/immunology , Influenza Vaccines/administration & dosage , Influenza, Human/prevention & control , Influenza, Human/epidemiology , Middle Aged , Adolescent , Adult , Primary Health Care/statistics & numerical data , United Kingdom/epidemiology , Aged , Young Adult , Child , Female , Male , Child, Preschool , Influenza A Virus, H3N2 Subtype/immunology , Influenza B virus/immunology , Influenza A Virus, H1N1 Subtype/immunology , Seasons , Vaccination/statistics & numerical dataABSTRACT
OBJECTIVES: We undertook a national analysis to characterise and identify risk factors for acute respiratory infections (ARIs) resulting in hospitalisation during the winter period in Scotland. DESIGN: A population-based retrospective cohort analysis. SETTING: Scotland. PARTICIPANTS: The study involved 5.4 million residents in Scotland. MAIN OUTCOME MEASURES: Cox proportional hazard models were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for the association between risk factors and ARI hospitalisation. RESULTS: Between 1 September 2022 and 31 January 2023, there were 22,284 (10.9% of 203,549 with any emergency hospitalisation) ARI hospitalisations (1759 in children and 20,525 in adults) in Scotland. Compared with the reference group of children aged 6-17 years, the risk of ARI hospitalisation was higher in children aged 3-5 years (aHR = 4.55; 95% CI: 4.11-5.04). Compared with those aged 25-29 years, the risk of ARI hospitalisation was highest among the oldest adults aged ≥80 years (aHR = 7.86; 95% CI: 7.06-8.76). Adults from more deprived areas (most deprived vs. least deprived, aHR = 1.64; 95% CI: 1.57-1.72), with existing health conditions (≥5 vs. 0 health conditions, aHR = 4.84; 95% CI: 4.53-5.18) or with history of all-cause emergency admissions (≥6 vs. 0 previous emergency admissions, aHR = 7.53; 95% CI: 5.48-10.35) were at a higher risk of ARI hospitalisations. The risk increased by the number of existing health conditions and previous emergency admission. Similar associations were seen in children. CONCLUSIONS: Younger children, older adults, those from more deprived backgrounds and individuals with greater numbers of pre-existing conditions and previous emergency admission were at increased risk for winter hospitalisations for ARI.