Background: Influenza vaccination has been suggested to be a trigger for bullous pemphigoid (BP). In our area most new patients with BP are admitted to hospital.
Objectives: To detect a difference in the rate of admissions to hospital for BP during population influenza vaccination programmes, which are mainly targeted at individuals aged 65 years or older, start in the last week of September and last for 2 months.
Methods: An ecological study in Galicia, north-west Spain (1997-2005), restricted to people aged 65 years or older. Using Poisson regression, results were controlled for mean age of admission and percentage of the population vaccinated each year.
Results: There were 29 admissions registered during 'vaccination periods' (i.e. approximately 10 weeks per year, including the period of vaccination and two further weeks), and 158 during nonvaccination periods (the rest of the year). The incidence rate ratio of admissions for BP in vaccination vs. nonvaccination periods was 0.85 (95% confidence interval 0.57-1.27, P = 0.43).
Conclusions: Our data do not support the hypothesis of influenza vaccination being an important trigger for severe BP on a population level.