Abstract
BACKGROUND: Pneumococcal carriage is associated with increased acquisition and duration of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among adults. While pneumococcal conjugate vaccines (PCVs) prevent carriage of vaccine-serotype pneumococci, their potential impact on coronavirus disease 2019 (COVID-19)-related outcomes remains poorly understood in populations with prevalent immunity against SARS-CoV-2. METHODS: We undertook a retrospective cohort study of adults aged ≥65 years in the Kaiser Permanente Southern California healthcare system who had received ≥2 COVID-19 vaccine doses, comparing risk of SARS-CoV-2 infection between 1 January 2021 and 31 December 2022 among recipients and nonrecipients of 13-valent PCV (PCV13) employing multiple strategies to mitigate bias from differential test-seeking behavior. RESULTS: The ajusted hazard ratio of confirmed SARS-CoV-2 infection comparing PCV13 recipients to nonrecipients was 0.92 (95% confidence interval [CI], .90-.95), corresponding to prevention of 3.9 (95% CI, 2.6-5.3) infections per 100 person-years. Following receipt of 2, 3, and ≥4 COVID-19 vaccine doses, aHRs (95% CI) were 0.85 (.81-.89), 0.94 (.90-.97), and 0.99 (.93-1.04), respectively. The aHR (95% CI) for persons who had not received COVID-19 vaccination in the preceding 6 months was 0.90 (.86-.93), versus 0.94 (.91-.98) within 6 months after COVID-19 vaccination. Similarly, aHRs (95% CI) were 0.92 (.89-.94) for persons without history of documented SARS-CoV-2 infection, versus 1.00 (.90-1.12) for persons with documented prior infection. CONCLUSIONS: Among older adults who had received ≥2 COVID-19 vaccine doses, PCV13 was associated with modest protection against SARS-CoV-2 infection. Protective effects of PCV13 were greater among individuals expected to have weaker immune protection against SARS-CoV-2 infection.