Effectiveness of influenza vaccination for preventing influenza-related complications in people with asthma: a systematic review protocol

Association between Influenza Vaccine Administration and Primary Care Consultations for Respiratory Infections: Sentinel Network Study of Five Seasons (2014/2015-2018/2019) in the UK

Influenza, a vaccine preventable disease, is a serious global public health concern which results in a considerable burden on the healthcare system. However, vaccine hesitancy is increasingly becoming a global problem. One prevalent misconception is that influenza vaccinations can cause the flu. We carried out this study to determine whether people undertaking influenza vaccination presented less with acute respiratory tract infection (ARTI) and influenza-like-illness (ILI) following vaccination. We utilised the Oxford Royal College of General Practitioners Research and Surveillance Centre sentinel database to examine English patients who received vaccination between 2014/2015 and 2018/2019. Of the 3,841,700 influenza vaccinations identified, vaccination details and primary care respiratory consultation counts were extracted to calculate the relative incidence (RI) per exposure risk period using the self-controlled case series methodology. Results showed a significant increase in the RI of respiratory consultation rates within fourteen days of vaccination across all five years. Less than 6.2% of vaccinations led to consultations for ARTI or ILI in primary care (crude consultation rate 6196 per 100,000). These findings, particularly if confirmed in further research, may reduce the risk of cross-infection between waiting patients and increase uptake of influenza vaccine.

Effectiveness of Influenza Vaccines in Asthma: A Systematic Review and Meta-Analysis

There is uncertainty about the effectiveness of influenza vaccination in persons with asthma and its impact on asthma outcomes, which may contribute to the suboptimal vaccination rates in persons with asthma. This systematic review and meta-analysis involved searching 12 international databases for randomized controlled trials (RCTs) and high-quality quasi-experimental and epidemiological studies (1970-2016). The risk of bias was low for 3 included RCTs. The quality of 3 included observational studies was moderate. The quality of evidence was very low for all study outcomes. Pooled vaccine effectiveness in 1825 persons with asthma from 2 test-negative design case-control studies was 45% (95% confidence interval [CI], 31%-56%) for laboratory-confirmed influenza. Pooled efficacy of live vaccines in reducing influenza was 81% (95% CI, 33%- 94%). Live vaccine reduced febrile illness by 72% (95% CI, 20%-90%). Influenza vaccine prevented 59%-78% of asthma attacks leading to emergency visits and/or hospitalizations. For persons with asthma, influenza vaccination may be effective in both reducing influenza infection and asthma attacks.

Evaluating the effectiveness, impact and safety of live attenuated and seasonal inactivated influenza vaccination: protocol for the Seasonal Influenza Vaccination Effectiveness II (SIVE II) study

INTRODUCTION

Seasonal (inactivated) influenza vaccination is recommended for all individuals aged 65+ and in individuals under 65 who are at an increased risk of complications of influenza infection, for example, people with asthma. Live attenuated influenza vaccine (LAIV) was recommended for children as they are thought to be responsible for much of the transmission of influenza to the populations at risk of serious complications from influenza. A phased roll-out of the LAIV pilot programme began in 2013/2014. There is limited evidence for vaccine effectiveness (VE) in the populations targeted for influenza vaccination. The aim of this study is to examine the safety and effectiveness of the live attenuated seasonal influenza vaccine programme in children and the inactivated seasonal influenza vaccination programme among different age and at-risk groups of people.

METHODS AND ANALYSIS

Test negative and cohort study designs will be used to estimate VE. A primary care database covering 1.25 million people in Scotland for the period 2000/2001 to 2015/2016 will be linked to the Scottish Immunisation Recall Service (SIRS), Health Protection Scotland virology database, admissions to Scottish hospitals and the Scottish death register. Vaccination status (including LAIV uptake) will be determined from the primary care and SIRS database. The primary outcome will be influenza-positive real-time PCR tests carried out in sentinel general practices and other healthcare settings. Secondary outcomes include influenza-like illness and asthma-related general practice consultations, hospitalisations and death. An instrumental variable analysis will be carried out to account for confounding. Self-controlled study designs will be used to estimate the risk of adverse events associated with influenza vaccination.

ETHICS AND DISSEMINATION

We obtained approval from the National Research Ethics Service Committee, West Midlands-Edgbaston. The study findings will be presented at international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN88072400; Pre-results.