PhD student Department of Health Convergence, College of Science and Industry Convergence, Ewha Womans University, Seoul, Republic of Korea Seodaemun-Gu, Republic of Korea
Background: The current recommendation for the elderly is to receive both a single dose 23-valent pneumococcal polysaccharide vaccine (PPSV-23) and an annual inactivated influenza vaccine. While concerns have been raised about the safety of the concomitant vaccination, little evidence has been found to establish safety profiles for this approach.
Objectives: To evaluate the safety of concomitant versus sequential administration of PPSV-23 and influenza vaccine.
Methods: We performed a retrospective cohort study using a linked database that combines vaccination registry from the Korea Disease Control and Prevention Agency and claims data from the National Health Insurance Service for the period between Jan 1, 2015, to Dec 31, 2021. The study population included all those aged over 65 and received PPSV-23 at least once from Jan 1 2016, to Dec 31, 2020. Concomitant vaccination was defined as receiving both PPSV-23 and influenza vaccine on the same day. For sequential vaccination, we defined it as receiving influenza vaccination during the period from 365 days to 30 days prior to the date of PPSV-23 injection. The prespecified AEs included Guillain-Barré syndrome, anaphylaxis, seizure and epilepsy, syncope, Bell’s palsy, erythema multiforme, cellulitis and infection, allergic reaction, leukocytosis, localized oedema, neuritis, paralysis, transverse myelitis, myasthenia gravis, pneumonia, all cause death identified by the ICD-10 code, which were selected based on common safety issues related to the pneumococcal and various other vaccines. Patients were followed from the date of the first administration of PPSV-23 until the earliest occurrence of AEs, death, any vaccination or the end of the follow-up period (anaphylaxis, syncope: 0-1 day; cellulitis and infection, allergic reaction, leukocytosis, localized oedema: 1-7 days; other AEs: 1-42 days following PPSV-23 vaccination). We performed 1:4 propensity score matching and estimated incidence rate ratio (IRR) with a 95% confidence interval (CI) using conditional Poisson regression, adjusted for sex, age, residence, Charlson comorbidity index (categorized as 0, 1, ≥2), and calendar month of vaccination.
Results: Among the 2,885,144 elderly patients who received PPSV-23 vaccination at least once from Jan 1, 2016, to Dec 31, 2020, a total 87,899 were included in the concomitant vaccination group and 1,200,091 were included in the sequential vaccination group. According to the initial analysis, the concomitant group exhibited a significantly higher risk of paralysis (IRR: 1.81, 95% CI: 1.20-2.73) and all-cause death (IRR: 1.11, 95% CI: 1.03-1.20), while demonstrating significantly lower risks of allergic reactions (IRR: 0.74, 95% CI: 0.61-0.90), neuritis (IRR: 0.71, 95% CI: 0.57-0.89), and pneumonia (IRR: 0.84, 95% CI: 0.79-0.89) compared to the sequential group. However, after adjusting for confounding factors, the only significantly increased risk observed in the concomitant group was for paralysis (IRR: 1.61, 95% CI: 1.04-2.48).
Conclusions: Concomitant administration of PPSV-23 and influenza vaccine in the elderly was not associated with a higher risk of most prespecified AEs compared to sequential vaccination. This study supports the safety of concomitant administration of PPSV-23 and influenza vaccine.
