RESUMO
We present England 2021/22 end-of-season adjusted vaccine effectiveness (aVE) against laboratory confirmed influenza related emergency care use in children aged 1-17 and in adults aged 50+, and serological findings in vaccinated vs unvaccinated adults by hemagglutination inhibition assay. Influenza vaccination has been routinely offered to all children aged 2-10 years and adults aged 65 years + in England. In 2021/22, the offer was extended to children to age 15 years, and adults aged 50-64 years. Influenza activity rose during the latter half of the 2021/22 season, while remaining comparatively low due to COVID-19 pandemic control measures. Influenza A(H3N2) strains predominated. A test negative design was used to estimate aVE by vaccine type. Cases and controls were identified within a sentinel laboratory surveillance system. Vaccine histories were obtained from the National Immunisation Management Service (NIMS), an influenza and COVID-19 vaccine registry. These were linked to emergency department presentations (excluding accidents) with respiratory swabbing ≤ 14 days before or ≤ 7 days after presentation. Amongst adults, 423 positive and 32,917 negative samples were eligible for inclusion, and 145 positive and 6,438 negative samples among children. Those admitted to hospital were further identified. In serology against the circulating A(H3N2) A/Bangladesh/4005/2020-like strain, 61 % of current season adult vaccinees had titres ≥ 1:40 compared to 17 % of those unvaccinated in 2020/21 or 2021/22 (p < 0.001). We found good protection from influenza vaccination against influenza requiring emergency care in children (72.7 % [95 % CI 52.7, 84.3 %]) and modest effectiveness in adults (26.1 % [95 % CI 4.5, 42.8 %]). Adult VE was higher for A(H1N1) (81 % [95 % CI 50, 93 %]) than A(H3N2) (33 % [95 % CI 6, 53 %]). Consistent protection was observable across preschool, primary and secondary school aged children. Imperfect test specificity combined with very low prevalence may have biased estimates towards null. With limited influenza circulation, the study could not determine differences by vaccine types.
Assuntos
Serviços Médicos de Emergência , Vírus da Influenza A Subtipo H1N1 , Vacinas contra Influenza , Influenza Humana , Adulto , Criança , Pré-Escolar , Humanos , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Estudos de Casos e Controles , Estações do Ano , Vírus da Influenza A Subtipo H3N2 , Vacinas contra COVID-19 , Pandemias/prevenção & controle , Vacinas contra Influenza/uso terapêutico , Inglaterra/epidemiologia , Vacinação , Atenção Primária à SaúdeRESUMO
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.
Assuntos
Vírus da Influenza A Subtipo H3N2 , Vírus da Influenza B , Vacinas contra Influenza , Influenza Humana , Atenção Primária à Saúde , Eficácia de Vacinas , Humanos , Vacinas contra Influenza/imunologia , Vacinas contra Influenza/administração & dosagem , Influenza Humana/prevenção & controle , Influenza Humana/epidemiologia , Pessoa de Meia-Idade , Adolescente , Adulto , Atenção Primária à Saúde/estatística & dados numéricos , Reino Unido/epidemiologia , Idoso , Adulto Jovem , Criança , Feminino , Masculino , Pré-Escolar , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza B/imunologia , Vírus da Influenza A Subtipo H1N1/imunologia , Estações do Ano , Vacinação/estatística & dados numéricosRESUMO
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.