This study is to understand how pregnant women feel about flu vaccine and how COVID-19 is affecting their beliefs. The flu can be dangerous for pregnant women and their babies. This is why the vaccine is so important. However, less than half of pregnant women get the flu vaccine. We want to understand why and how we can help increase the number of pregnant women having the flu vaccine.
We will use anonymous health records to compare flu-like disease, pregnancy outcomes, and antibiotic prescription in vaccinated pregnant and unvaccinated pregnant women and in their infant children. The link between number of people vaccinated and health inequalities will be investigated.
This study will help us to design a factual positive message about the flu vaccine for pregnant women. The delivery and content of this message will be designed in collaboration with pregnant women. Higher acceptance of the vaccine will help protect pregnant women and their babies from flu illness and any bad effects that can come from it. We also want to increase their knowledge about the flu and its vaccine.
Aim: To describe outcomes/effects of influenza vaccination in pregnant women and their children during pregnancy and in the first 6 months after birth.
Methods: A cohort study will be conducted using routinely collected data through the Clinical Practice Research Datalink (CPRD Gold).
Population: The Pregnancy Register and Mother Baby Link data will be used to analyse family units. We will extract a cohort of pregnant women who had recorded pregnancy between January 2012 and December 2019. Following up the linked children up to 6 months of age.
Exposures and outcomes: CPRD primary care data will be used to identify influenza vaccine status during a pregnancy. We will use CPRD data and Health Episode Statistics (HES) discharge diagnosis coding to establish acute respiratory infection events including hospitalised influenza-associated illness (IAI), hospitalised severe acute respiratory infection (SARI), and influenza-like illness in primary care in pregnant women and their new-born infants up to 6 months of age. We will also assess outcome of pregnancy and antibiotic prescribing (AP) associated with acute respiratory infection consultations.
Covariates: Socioeconomic status, age, ethnicity, GP, geography, pertussis vaccination and comorbidity will be accounted for in analyses. Socioeconomic deprivation is associated with increased risk of complications from influenza infection and lower vaccine uptake. Influenza disease and complications are more common in those with certain pre-existing conditions. These are defined in the Green Book (PHE, 2018), and will be identified from CPRD patient files.
Data analysis: We will evaluate associations between influenza vaccine uptake during pregnancy and various covariates. We will use appropriate generalized linear models to consider the association between outcome (IAI, SARI, acute respiratory infection, AP, pregnancy outcome) and vaccination with appropriate adjustments for known confounders and annual vaccine/influenza subtype matching.
Primary outcome: Uptake of influenza vaccine by parity, age, geography, and socio-economic group.
Secondary outcomes: primary care acute respiratory infection consultations; hospitalised influenza-associated illness (IAI); hospitalised severe acute respiratory infection (SARI); outcome of pregnancy (e.g. miscarriage, still birth, pre-term birth, termination of pregnancy); IAI and SARI hospitalisations and acute respiratory infection consultation in infants in first 6 months of life, neonatal deaths within the first 6 months; antibiotic prescription for acute respiratory infection consultations in pregnant mothers and their infants.
Exposure for secondary outcomes: Influenza vaccination during pregnancy.
Neil French - Chief Investigator - University of Liverpool
Samantha Kilada - Corresponding Applicant - University of Liverpool
Caroline Jeffery - Collaborator - University of Liverpool
Daniel Hungerford - Collaborator - University of Liverpool
David Salac - Collaborator - University of Liverpool
David Singleton - Collaborator - University of Liverpool
Elizabeth Perkins - Collaborator - University of Liverpool
CPRD Mother-Baby Link;HES Admitted Patient Care;Patient Level Index of Multiple Deprivation;Pregnancy Register;Rural-Urban Classification