Epidemiological Trends and Influencing Factors of Influenza Virus Infections in Respiratory Tract Infection Patients at Ramathibodi Hospital: A Decade of Molecular Surveillance (2012-2022)
Keywords:
influenza virus, respiratory tract infection, real-time RT-PCRAbstract
The objective of this study was to study epidemiological trends and factor influencing on the detection of influenza virus in Ramathibodi Hospital, Mahidol University, Thailand. It was conducted by analyzing epidemiological data from 42,940 patients presenting with respiratory tract infections and screened for influenza virus using real-time reverse transcription polymerase chain reaction (real-time RT-PCR) between January 2012 and December 2022. The findings indicated that 3,020 cases (7.03%) were positive for the influenza virus. The distribution of influenza cases included 1,845 cases (61.09%) of influenza A, 1,160 cases (38.41%) of influenza B, 8 cases (0.26%) of influenza C, and 7 cases (0.23%) with co-infection of both influenza A and B. Of these, 656 cases (35.56%) were H1N1 subtype A, 900 cases (48.78%) were H3N2, and 289 cases (15.66%) were of an unidentified strain. The period of peak influenza infection extends from August to October, while the season with the lowest number of infections occurs between April and June. The relationship between age and the risk of influenza infection indicates that young children and adults exhibited a significantly higher risk of influenza infection compared with older adults. The relative risk values for this relationship are 1.85 (p<0.001, OR = 1.85, 95%CI = 1.54 - 2.24) and 1.44 (p<0.001, OR = 1.44, 95%CI = 1.25 - 1.66), respectively. After the emergence of the COVID-19 pandemic, a statistically significant association with the detection of influenza virus was observed (p<0.001, OR = 1.28, 95%CI = 1.13 – 1.45). The study found no statistically significant correlation between gender and sample type on the presence of the influenza virus. These findings may be used to inform preparedness strategies to prepare for future influenza pandemics.
Downloads
References
Sitthikarnkha P, Uppala R, Niamsanit S, Sutra S,Thepsuthammarat K, Techasatian L, et al. Epidemiology of acute lower
respiratory tract infection hospitalizations in Thai children: a 5-year national data analysis. Influenza Other Respir Viruses
;16(1):142-50.
World Health Organization. Influenza in the northern hemisphere is back [Internet]. 2022 [cited 2026 Jan 16].
Available from: https://www.who.int/news/item/14-10-2022-influenza-in-the-northern-hemisphere-isback#
World Health Organization. Influenza update N° 430 [Internet]. 2022 [cited 2026 Jan 16]. Available from:
https://www.who.int/publications/m/item/influenzaupdate-n-430
Bonacina F, Boëlle PY, Colizza V, Lopez O, Thomas M, Poletto C. Global patterns and drivers of influenza decline during
the COVID-19 pandemic. Int J Infect Dis 2023;128:132-9.
Tasar S, Karadag-Oncel E, Yilmaz-Ciftdogan D,Kara-Aksay A, Ekemen-Keles Y, Elvan-Tuz A, et al. Influenza is more severe
than our newest enemy (COVID-19) in hospitalized children: experience from a tertiary center. J Med Virol
;94(9):4107-14.
Moghoofei M, Monavari SH, Mostafaei S, Hadifar S, Ghasemi A, Babaei F, et al. Prevalence of influenza A infection
in the Middle-East: a systematic review and meta-analysis. Clin Respir J 2018;12(5):1787-801.
Javanian M, Barary M, Ghebrehewet S, Koppolu V, Vasigala V, Ebrahimpour S. A brief review of influenza virus infection.
Journal of Medical Virology 2021; 93(8):4638-46.
Miller JM, Binnicker MJ, Campbell S, Carroll KC, Chapin KC, Gilligan PH, et al. A guide to utilization of the microbiology
laboratory for diagnosis of infectious diseases: 2018 update by the Infectious Diseases Society of America and the
American Society for Microbiology. Clinical Infectious Diseases 2018;67(6):e1-94.
World Health Organization. Guidelines for the clinical management of severe illness from influenza virus infec-[Internet].
[cited 2026 Jan 16]. Available from: https://iris.who.int/bitstream/handle/10665/352453/9789240040816-eng.pdf?
sequence=1&isAllowed=y
Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD).
Information on collection of respiratory specimens for influenza virus testing [Internet]. 2022 [cited2026 Jan 16].
Available from: https://www.cdc.gov/ flu/professionals/diagnosis/info-collection.htm.
Iuliano AD, Roguski KM, Chang HH, Muscatello DJ, Palekar R, Tempia S, et al. Estimates of global seasonal
influenza-associated respiratory mortality: a modellingstudy. Lancet 2018;391(10127):1285-300.
Paules C, Subbarao K. Influenza. Lancet 2017;390(10095):697-708.
Chittaganpitch M, Supawat K, Olsen SJ, Waicharoen S,Patthamadilok S, Yingyong T, et al. Influenza viruses in
Thailand: 7 years of sentinel surveillance data, 2004-2010. Influenza Other Respir Viruses 2012;6(4):276-83.
Lehners N, Tabatabai J, Prifert C, Wedde M, Puthenparambil J, Weissbrich B, et al. Long-term shedding of influenza
virus, parainfluenza virus, respiratory syncytial virus and nosocomial epidemiology in patients with hematological
disorders. PLOS One 2016;11(2):e0148258.
Narong N, Manajit S, Athipanyasil S, Athipanyasilp N, Sutthent R, Kantakamalakul W, et al. Prevalence of influenza virus
type and subtype at Siriraj Hospital, Bangkok, Thailand During 2013 - 2017. Rama Med J 2020;43(3):1-7.
Tokars JI, Olsen SJ, Reed C. Seasonal incidence of symptomatic influenza in the United States. Clin Infect Dis
;66(10):1511-8.
Rakmanee K, Watthanachockchai T. A ten-year retrospective study on patterns of pathogens in acute respiratory tract
infection at Ramathibodi Hospital, Thailand. Bulletin of The Department of Medical Sciences 2025;67(4):611-24.
Irving SA, Vandermause MF, Shay DK, Belongia EA. Comparison of nasal and nasopharyngeal swabs for influenza
detection in adults. Clin Med Res 2012;10(4):215-8.
Labhardt ND, González Fernández L, Katende B, Muhairwe J, Bresser M, Amstutz A, et al. Head-to-head comparison
of nasal and nasopharyngeal sampling using SARS-CoV-2 rapid antigen testing in Lesotho. PLOS One 2023;18(3):e0278653.
Soo RJJ, Chiew CJ, Ma S, Pung R, Lee V. Decreased influenza incidence under COVID-19 control measures, Singapore.
Emerg Infect Dis 2020;26(8):1933-5.
Olsen SJ, Azziz-Baumgartner E, Budd AP, Brammer L, Sullivan S, Pineda RF, et al. Decreased influenza activity during
the COVID-19 pandemic-United States, Australia, Chile, and South Africa, 2020. Am J Transplant 2020;20(12):3681-5.
Shokri A, Moradi G, Moradpour F, Mohamadi Bolbanabad A, Younesi F, Daftarifard P, et al. Influenza incidence
overlapped with COVID-19 or under COVID-19 control measures. Immun Inflamm Dis 2022;10(8):e672.
Morris SE, Nguyen HQ, Grijalva CG, Hanson KE, Zhu Y, Biddle JE, et al. Influenza virus shedding and symptoms:
dynamics and implications from a multiseason household transmission study. PNAS Nexus 2024;3(9):pgae338.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Ministry of Public Health
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
