Both systems are laboratory-based surveillance platforms aimed at monitoring the activity of important respiratory pathogens. However, they differ in specimen sources, testing methods, reporting timeliness, etc. These systems complement each other as part of a multi-source surveillance approach to enhance sensitivity. Interpretation of trends should be made in conjunction with various surveillance indicators for a comprehensive assessment of the epidemic situation.

Due to practical needs, the age stratification method of the NHIA data has been adjusted. Starting from March 13, 2025, the NHIA data will be reprocessed. As a result, historical health insurance consultation data has been modified since 2016.

The source of data on pathogen detection is from Contracted Virology Laboratories surveillance. Before 2024 (inclusive), the laboratories adopted the testing method of virus isolation, culture, and identification. Since 2025, the testing method has been adjusted to molecular detection; therefore, the results from these two methods will be presented separately.

1. The trend chart includes variants classified by the World Health Organization as current or former variants of interest (VOI), variants under monitoring (VUM), key domestic variants, and others (e.g. recombinant variants).
2. In the future, variant information may be adjusted due to factors such as the inclusion of new variants by the WHO, reclassification/renaming of variants, or the need for enhanced monitoring.

The Real-time Outbreak and Disease Surveillance System (RODS) collects and analyzes data from more than 170 designated hospitals nationwide. Through this system, diagnostic codes and other related information from emergency departments are automatically and continuously transmitted in real time to the Taiwan Centers for Disease Control (TCDC).
The system enables early and rapid detection of abnormal patterns or signals in various diseases or syndromes. It was established to identify potential infectious disease outbreaks in the community at an early stage and to track and forecast epidemic trends.
In 2007, the system monitored influenza-like illness (ILI), enterovirus infection, and diarrhea. Since 2008, acute hemorrhagic conjunctivitis (AHC) has also been included as a monitored disease.
Data Analysis Method: Over 170 designated hospitals transmit emergency department data in real time via the Internet every day. The main data fields include basic patient information, hospital code, admission time, chief complaint, and ICD-9-CM/ICD-10-CM diagnostic codes.
The TCDC compiles and analyzes RODS data weekly to assess epidemic trends and produces statistical charts, which are published on the official TCDC website.

Example of citation: "Taiwan National Infectious Disease Statistics System [Internet]. Taipei (Taiwan): Taiwan Centers for Disease Control; c2014 [updated 2014 Apr 13; cited 2014 Apr 15]. Available from: http://nidss.cdc.gov.tw/en/."

Alert threshold: The mean number of confirmed cases for each corresponding week over the past five years.
Epidemic threshold: The mean number of confirmed cases for each corresponding week over the past five years plus two times the standard deviation (mean + 2 × SD).

Week calculation: Each week begins on Sunday and ends on Saturday. Week 1 of each year is defined as the week that includes January 4.
For a complete correspondence between weeks and calendar dates, please refer to the “Week–Year Reference Table.”

The Taiwan National Infectious Disease Statistics System is derived from the Taiwan CDC Data Warehouse System.
Statistical data on notifiable infectious diseases are updated daily at 8:30 a.m. Data from LARS, RODS, and National Health Insurance secondary statistics are updated early every Monday and Tuesday morning to ensure the completeness of weekly data. The datasets on “Nationwide Weekly Molecular Detection of Respiratory Pathogens / Influenza Viruses / Enteroviruses” are updated early every Saturday and Sunday morning.

Some downloaded datasets may contain fields that Excel automatically converts to date formats.
To prevent this issue, you can open the file using a plain text editor (such as Notepad, Notepad++, or WordPad), or by processing it through a program interface.
If you need to work with the data in Excel, please follow the steps below after downloading the file:
On the toolbar, select“Data”→“Get External Data”→“From Text File.”Choose comma-separated (CSV) as the delimiter.
When specifying column formats, set fields such as “Age group” to Text before importing.
This will prevent Excel from automatically converting numeric or text values into dates.

After the outbreak of the novel influenza A (H1N1) in mid-April 2009, the Taiwan CDC collaborated with the Department of Statistics, Ministry of Health and Welfare, to establish a mortality surveillance system for pneumonia and influenza.
Through the Death Reporting Network System, daily death notifications are electronically transmitted to Taiwan CDC. Causes of death identified by searching for the keywords pneumonia, common cold, or influenza, and analyzed in conjunction with cause-of-death classification rules to generate weekly statistics on pneumonia and influenza mortality trends.
For details on the data analysis method, please refer to:
http://www.cdc.gov.tw/downloadfile.aspx?fid=03531D876CD55C48

Explanation of the epidemic threshold:

1. Calculation Method: The mean and standard deviation (SD) are calculated based on the number of outpatient and emergency visits for enterovirus infection during non-epidemic weeks over the past three years.
The epidemic threshold is defined as mean+1.64×SD (the upper limit of the 90% confidence interval).

Note: Non-epidemic weeks are defined as weeks in which the number of enterovirus-positive specimens in the community accounts for less than 1.92% of the total annual number of positive specimens for two consecutive weeks.

(Assuming enterovirus-positive specimens are evenly distributed across 52 weeks in a year, the expected weekly percentage would be 1/52=1.92%.)

2. Interpretation: When the total number of outpatient and emergency visits for enterovirus infection exceeds the epidemic threshold, it indicates that the enterovirus infection has entered the epidemic phase.

‧Enterovirus infection: 008.67, 047, 047.0, 047.1, 048, 074, 074.0, 074.1, 074.2, 074.20, 074.21, 074.22, 074.23, 074.3, 074.8, 079.1, 079.2
‧Herpangina: 074.0
‧Hand, foot and mouth disease: 074.3
‧Acute hemorrhagic conjunctivitis (AHC): 077, 077.0, 077.1, 077.2, 077.3, 077.4, 077.8, 077.9, 370.4, 370.40, 372, 372.0, 372.00, 372.71, 372.72
‧Influenza-like illness (RODS ILI): 003.22, 010, 010.0, 010.00, 010.01, 010.02, 010.03, 010.04, 010.05, 010.06, 010.1, 010.10, 010.11, 010.12, 010.13, 010.14, 010.15, 010.16, 010.8, 010.80, 010.81, 010.82, 010.83, 010.84, 010.85, 010.86, 010.9, 010.90, 010.91, 010.92, 010.93, 010.94, 010.95, 010.96, 011, 011.0, 011.00, 011.01, 011.02, 011.03, 011.04, 011.05, 011.06, 011.1, 011.10, 011.11, 011.12, 011.13, 011.14, 011.15, 011.16, 011.2, 011.20, 011.21, 011.22, 011.23, 011.24, 011.25, 011.26, 011.3, 011.30, 011.31, 011.32, 011.33, 011.34, 011.35, 011.36, 011.4, 011.40, 011.41, 011.42, 011.43, 011.44, 011.45, 011.46, 011.5, 011.50, 011.51, 011.52, 011.53, 011.54, 011.55, 011.56, 011.6, 011.60, 011.61, 011.62, 011.63, 011.64, 011.65, 011.66, 011.7, 011.70, 011.71, 011.72, 011.73, 011.74, 011.75, 011.76, 011.8, 011.80, 011.81, 011.82, 011.83, 011.84, 011.85, 011.86, 011.9, 011.90, 011.91, 011.92, 011.93, 011.94, 011.95, 011.96, 020, 020.3, 020.4, 020.5, 020.9, 021.2, 022, 022.1, 024, 025, 032, 032.0, 032.1, 032.2, 032.3, 032.89, 033, 033.0, 033.1, 033.8, 033.9, 034, 034.0, 052.1, 055.1, 073, 073.0, 074.1, 079, 079.8, 079.81, 079.88, 079.89, 079.9, 079.98, 079.99, 083.0, 112.4, 114.0, 114.9, 115, 115.0, 115.00, 115.05, 115.15, 115.9, 115.90, 115.95, 130.4, 136.3, 460, 462, 463, 464, 464.0, 464.1, 464.10, 464.11, 464.2, 464.20, 464.21, 464.3, 464.30, 464.31, 464.4, 465, 465.0, 465.8, 465.9, 466, 466.0, 466.1, 466.11, 466.19, 480, 480.0, 480.1, 480.2, 480.8, 480.9, 481, 482, 482.0, 482.1, 482.2, 482.3, 482.30, 482.31, 482.32, 482.39, 482.4, 482.40, 482.41, 482.49, 482.8, 482.81, 482.82, 482.83, 482.84, 482.89, 482.9, 483, 483.0, 483.1, 483.8, 484, 484.1, 484.3, 484.5, 484.6, 484.7, 484.8, 485, 486, 487, 487.0, 487.1, 490, 491, 491.0, 491.1, 491.20, 491.21, 491.8, 491.9, 507, 507.0, 507.1, 507.8, 511, 511.0, 511.1, 511.8, 511.9, 513, 513.0, 513.1, 518, 518.0, 518.4, 518.8, 518.81, 518.82, 518.84, 518.89, 519.2, 784.1, 786.0, 786.00, 786.05, 786.06, 786.07, 786.09, 786.1, 786.2, 786.52, 795.31, V01.81
see also Chapman et al, Generating a Reliable Reference Standard Set for Syndromic Case Classification, J Am Med Inform Assoc. 2005 Nov-Dec;12(6):618-29.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1294033/pdf/618.pdf

‧Acute diarrhea: 001, 001.0, 001.1, 001.9, 002, 002.0, 002.1, 002.2, 002.3, 002.9, 003, 003.0, 003.1, 003.2, 003.20, 003.21, 003.22, 003.23, 003.24, 003.29, 003.8, 003.9, 004, 004.0, 004.1, 004.2, 004.3, 004.8, 004.9, 005.0, 005.1, 005.2, 005.3, 005.4, 005.8, 005.81, 005.89, 005.9, 006, 006.0, 006.2, 006.9, 007, 007.0, 007.1, 007.2, 007.3, 007.4, 007.5, 007.8, 007.9, 008, 008.0, 008.00, 008.01, 008.02, 008.03, 008.04, 008.09, 008.1, 008.2, 008.3, 008.4, 008.41, 008.42, 008.43, 008.44, 008.45, 008.46, 008.47, 008.49, 008.5, 008.6, 008.61, 008.62, 008.63, 008.64, 008.65, 008.66, 008.67, 008.69, 008.8, 009, 009.0, 009.1, 009.2, 009.3, 558, 558.9, 787.91, 988
‧COVID-19 infection: U07.1

Disease		ICD-9	ICD-10
Enterovirus infection	Hand, foot and mouth disease	074.3	B08.4
	Herpangina	074.0	B08.5
Influenza-like illness(ILI)	Other pneumonia	480	J12-
		481	J13-
		482	J14-
			J15-
		483	J16-
		484	B25-
			A37-
			A22-
			B44-
			J17-
		485
		486	J18-
	Influenza and pneumonia caused by influenza	487	J09-
			J10-
			J11-
Acute upper respiratory infection		465.9	J06.9
Diarrhea		009.0	A08-
		558.9	K52-
		787	R19.7
Scarlet fever		034.1	A38-
Varicella		052-	B01-
COVID-19 infection			U07.1
Acute hemorrhagic conjunctivitis (AHC)	Viral conjunctivitis		B30-
	Conjunctivitis		H10-
	Conjunctival hemorrhage		H11.3-