{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,10]],"date-time":"2026-11-10T01:00:10Z","timestamp":1794272410297,"version":"4.9.0"},"reference-count":15,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T00:00:00Z","timestamp":1784764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"crossref"}]},{"id":[{"id":"https:\/\/ror.org\/013aysd81","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003725","name":"Korean government","doi-asserted-by":"publisher","award":["RS-2024-00341570"],"award-info":[{"award-number":["RS-2024-00341570"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Background: Notifiable infectious diseases impose a substantial, evolving burden on public health systems. This study characterized long-term epidemiological trends, inter-class associations, and age-stratified patterns of notifiable infectious diseases in South Korea and projected future burden through 2028. Methods: We analyzed aggregate national surveillance data (2001\u20132024) from the Korea Disease Control and Prevention Agency (KDCA) via the Korean Statistical Information Service (KOSIS). Because the statutory classification changed in 2020 from a four-group (Class 1\u20134, gun) to a four-grade (geup) system, all inferential trend, correlation, and forecasting analyses were restricted to the internally consistent 2001\u20132019 group-system period, and 2020\u20132024 grade-system data were used descriptively. Secular trends were estimated with ordinary least squares and, for count-specific inference, negative-binomial log-linear models (annual percent change, APC); residual autocorrelation was assessed (Durbin\u2013Watson, Ljung\u2013Box). Structural breaks were estimated objectively (Bai\u2013Perron least-squares). Inter-class associations were tested with Pearson\/Spearman correlations and re-evaluated with partial correlation (controlling for calendar year) and first-difference detrending to guard against spurious co-trending. Forecasts used a random-walk ARIMA (identified by ADF stationarity testing, ACF\/PACF, and AICc) and a damped Holt\u2013Winters model on the H1N1-adjusted series, combined into an ensemble; performance was validated by rolling-origin cross-validation (RMSE, MAE, MAPE). Results: After handling the 2009 H1N1 pandemic outlier, total notifications rose significantly over 2001\u20132019 (slope = 8344 cases\/year; 95% CI 6603\u201310,084; R2 = 0.866; p &lt; 0.001). Class 2 (respiratory\/vaccine-preventable) diseases showed the strongest trend (APC = 17.2%\/year; 95% CI 8.0\u201327.3), with an objectively estimated structural break at 2004 (supF = 10.5) separating an early variable phase from sustained growth (2005\u20132019: +7418 cases\/year; R2 = 0.94). Raw Class 1\u2013Class 2 correlation (Pearson r = 0.569, p = 0.011) did not survive temporal adjustment (partial r = 0.13, p = 0.59; detrended r = \u22120.31, p = 0.21), indicating shared secular co-trending rather than a direct epidemiological association; only Class 2\u2013Class 3 remained associated after detrending (r = 0.52, p = 0.03). Young working-age adults (30\u201349 years) showed the steepest Class 1 increases. Ensemble projections for the pre-COVID trajectory were 238,000 (2025) to 269,000 (2028) annual notifications, with wide prediction intervals reflecting substantial uncertainty. Conclusions: South Korean notifiable-disease epidemiology was dominated by a genuine upward Class 2 respiratory trend; several previously reported inter-class correlations were attributable to common temporal trends rather than shared transmission. Post-COVID normalization monitoring and respiratory-disease surveillance investment are priority actions.<\/jats:p>","DOI":"10.3390\/pathogens15080780","type":"journal-article","created":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T09:11:26Z","timestamp":1784797886000},"page":"780","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Epidemiological Trends, Statistical Correlations, and Forecasting of Notifiable Infectious Diseases in South Korea, 2001\u20132024: A Regression and Time Series Analysis with Projections to 2028"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-2428-2677","authenticated-orcid":false,"given":"Hyeran","family":"Jung","sequence":"first","affiliation":[{"name":"Department of Pathology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Minsun","family":"Jung","sequence":"additional","affiliation":[{"name":"Department of Pathology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,23]]},"reference":[{"key":"ref_1","unstructured":"Korea Disease Control and Prevention Agency (KDCA) (2026, June 20). 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Soc."}],"container-title":["Pathogens"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/8\/780\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,25]],"date-time":"2026-07-25T04:17:51Z","timestamp":1784953071000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/8\/780"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,23]]},"references-count":15,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["pathogens15080780"],"URL":"https:\/\/doi.org\/10.3390\/pathogens15080780","relation":{},"ISSN":["2076-0817"],"issn-type":[{"value":"2076-0817","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,23]]}}}