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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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

2013/14 saw the start of the introduction of a new live attenuated influenza vaccine (LAIV) programme for children in England. 2018/19 saw co-circulation of both A(H1N1)pdm09 and A(H3N2), when LAIV was offered to all healthy children 2-9 years of age. LAIV effectiveness against influenza hospitalisation is not well described. This paper presents the 2018/19 end-of-season adjusted vaccine effectiveness (aVE) against laboratory confirmed influenza related hospitalisation in children aged 2-17. The test negative case control approach was used to estimate aVE by influenza A subtype and vaccine type. Cases and controls were selected from a sentinel laboratory surveillance system which collates details of individuals tested for influenza with reverse-transcription polymerase chain reaction (RT-PCR) on respiratory samples. Vaccine and clinical history was obtained from general practitioners of study participants. There were 307 hospitalised cases and 679 hospitalised controls. End-of-season influenza aVE was 53.0% (95% CI: 33.3, 66.8) against influenza confirmed hospitalisation; 63.5% (95% CI: 34.4, 79.7) against influenza A(H1N1)pdm09 hospitalisation and 31.1% (95% CI: -53.9, 69.2) against influenza A(H3N2). LAIV aVE was 49.1% (95% CI: 25.9, 65.0) for any influenza and 70.7% (95% CI: 41.8, 85.3) for A(H1N1)pdm09, whereas for those receiving quadrivalent inactivated influenza vaccine (QIV), aVE was 64.4% (95% CI: 29.4, 82.0) and 44.4% (95% CI: -51.9, 79.6) respectively. We provide evidence of overall significant VE for both LAIV and QIV against influenza associated hospitalisation in children 2-17 years of age, most notably against influenza A(H1N1)pdm09, with non-significant protection against A(H3N2)., (Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.)

The hypothesis that hepatitis B vaccination is a risk factor for multiple sclerosis has been discussed at length. The data from an earlier case-control study were reanalyzed using the self-controlled case series method. Using the matched cases from the case-control study, we found a relative incidence of 1.68, 95% CI (0.77-3.68) for the 0-60-day post-vaccination risk period; this compares to an odds ratio of 1.8, 95% CI (0.7-4.6). When an additional 53 unmatched cases not used in the case-control study were included, the relative incidence was 1.35, 95% CI (0.66-2.79). Our results throw further light on the methodological aspects of the case series method. We recommend that, when case-control studies of vaccination and adverse events are planned, case series analyses based on the cases are also undertaken when appropriate.