JMIR Publications

ABSTRACT

Background:

Innovation in seasonal influenza vaccine development has resulted in a wider range of formulations becoming available. Understanding vaccine coverage across populations including the timing of administration is important when evaluating vaccine benefit-risk.

Objective:

We carried out this study to report the representativeness of the English primary care sentinel cohort (PCSC), the uptake of influenza vaccines, and the different formulations of influenza vaccine and timing of administration within this cohort.

Methods:

We used the PCSC of the Oxford-Royal College of General Practitioners Research and Surveillance Centre (RSC). We included patients of all ages registered with PCSC member general practices, reporting influenza vaccine coverage between September 1, 2019, and January 29, 2020. We identified influenza vaccination recipients and characterized them by age, clinical risk groups, and vaccine type. We reported date of influenza vaccination within the PCSC by International Standards Organization (ISO) week. The representativeness of the PCSC population was compared with population data provided by the Office for National Statistics (ONS). PCSC influenza vaccine coverage was compared with published UK Health Security Agency’s national data. We used paired t-tests to compare populations, reported with 95% confidence intervals (95% CI).

Results:

The PCSC comprised 7,010,627 people from 693 general practices. The study population included a greater proportion of people aged 18-49 years (42.5% [95% CI 42.5%–42.6%]) compared to the ONS 2019 mid-year population estimates (41.3% [4.12%–41.3%]; P<.00001). People who are more deprived were under-represented and those in the least deprived quintile over-represented. Within the study population, 1,731,062 people (24.7% [24.7%–24.7%]) of all ages received an influenza vaccine compared to 24.2% (24.2%-24.2%; P<.00001) in national data. The highest coverage was in people ≥65 years (72.3% [72.2%–72.3%]). The proportion of people in risk groups who received an influenza vaccine was also higher; for example, 69.8% (69.7%–70.0%) of people with diabetes in the PCSC received an influenza vaccine compared with 61.2% (61.1%–61.3%; P<.00001) in national data. In the PCSC, vaccine type and brand information were available for 71.8% (71.7%–72.0%) of people 16-64 years and 81.9% (81.8%–82.0%) ≥65 years, compared with 23.6% and 17.8%, respectively, of the same age groups in national data. Vaccination commenced during ISO week 35, continued until ISO week 3, and peaked during week 41. The in-week peak in vaccination administration was on Saturdays, especially for those aged ≥65 years. People aged ≥65 years also received their vaccinations earlier in the season than other groups.

Conclusions:

The PCSC’s sociodemographic profile was similar to the national population and captured more data about risk groups, vaccine brand, and batch. This may reflect higher data quality. Its capabilities included reporting precise date of administration. The PCSC is suitable for undertaking studies of influenza vaccine coverage. Clinical Trial: This study was classified as a service evaluation (measuring what standard of care this service achieved) by the Medical Research Council/Health Research Authority decision tool [38], so did not require formal ethical approval. It was approved by the RCGP Approval Committee on January 8, 2021.