{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T15:13:04Z","timestamp":1788880384610,"version":"build-2803163510"},"reference-count":28,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: This study evaluated changes in routine adult vaccination across the COVID-19 pandemic period in Istanbul primary care using interrupted time series (ITS) analysis, disentangling immediate from gradual effects and comparing patterns across socioeconomically distinct centers, through a multicenter retrospective analysis of routine (non-COVID-19 vaccination records). Methods: The full descriptive dataset comprised 33,016 adult vaccination records. After excluding 25,805 COVID-19 vaccination records, 7211 routine (non-COVID-19) vaccination records from nine family medicine units in three Istanbul training family health centers\u2014\u015ei\u015fli-G\u00fclbahar, Ka\u011f\u0131thane, and Gaziosmanpa\u015fa\u2014were included in the routine vaccine and ITS analyses and were analyzed over 97 monthly observations (June 2017\u2013August 2025), divided into three 672-working-day periods: pre-pandemic, pandemic, and post-pandemic. Segmented negative binomial ITS regression with a log (working days) offset was the primary analysis; Newey-West HAC-robust Poisson regression served as sensitivity analysis. Catchment districts were characterized using the 2022 Socioeconomic Development Ranking (SEGE-2022). Results: No significant immediate level change occurred in total routine vaccination at pandemic onset. Pneumococcal vaccination showed the most pronounced signal: an upward pretrend (annual slope IRR = 2.583; p = 0.001), a level increase at onset (IRR = 3.589; p = 0.013), then a rapid within-pandemic slope decline (annual slope IRR = 0.227; p &lt; 0.001). Tetanus-diphtheria (Td) vaccination fell sharply at onset (IRR = 0.686; p = 0.002) and continued declining post-pandemic (annual slope IRR = 0.805; p = 0.008). Versus Gaziosmanpa\u015fa (rank 85\/973), Ka\u011f\u0131thane (rank 38) showed the highest total routine vaccination rate (excluding COVID-19 vaccination) (IRR = 1.539; p &lt; 0.001), exceeding \u015ei\u015fli (rank 1; IRR = 1.269; p &lt; 0.001). Conclusions: Changes in routine adult vaccination across the pandemic period were vaccine-specific: pneumococcal vaccination surged then declined; Td vaccination showed continued post-pandemic decline. Center-level vaccination patterns were not consistently aligned with district-level socioeconomic ranking.<\/jats:p>","DOI":"10.3390\/vaccines14090785","type":"journal-article","created":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T14:55:46Z","timestamp":1788879346000},"page":"785","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of the COVID-19 Pandemic on Routine Adult Vaccination in Primary Care: A Multicenter Interrupted Time Series Analysis"],"prefix":"10.3390","volume":"14","author":[{"given":"Beg\u00fcm","family":"Y\u0131ld\u0131r\u0131m Erence","sequence":"first","affiliation":[{"name":"Department of Family Medicine, Istanbul Prof. Dr. Cemil Ta\u015fc\u0131o\u011flu City Hospital, Istanbul 34384, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Feyzanur","family":"Erdem","sequence":"additional","affiliation":[{"name":"Department of Family Medicine, Istanbul Prof. Dr. Cemil Ta\u015fc\u0131o\u011flu City Hospital, Istanbul 34384, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Ebru","family":"Tepe","sequence":"additional","affiliation":[{"name":"Department of Family Medicine, Istanbul Prof. Dr. Cemil Ta\u015fc\u0131o\u011flu City Hospital, Istanbul 34384, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Se\u00e7il","family":"Ar\u0131ca","sequence":"additional","affiliation":[{"name":"Department of Family Medicine, Istanbul Prof. Dr. Cemil Ta\u015fc\u0131o\u011flu City Hospital, Istanbul 34384, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,8]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2026, July 17). 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