PMID- 37034752 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20231122 DP - 2023 Mar 29 TI - A combination of annual and nonannual forces drive respiratory disease in the tropics. LID - 2023.03.28.23287862 [pii] LID - 10.1101/2023.03.28.23287862 [doi] AB - BACKGROUND: It is well known that influenza and other respiratory viruses are wintertime-seasonal in temperate regions. However, respiratory disease seasonality in the tropics remains elusive. In this study, we aimed to characterize the seasonality of influenza-like illness (ILI) and influenza virus in Ho Chi Minh City (HCMC), Vietnam. METHODS: We monitored the daily number of ILI patients in 89 outpatient clinics from January 2010 to December 2019. We collected nasal swabs and tested for influenza from a subset of clinics from May 2012 to December 2019. We used spectral analysis to describe the periodicities in the system. We evaluated the contribution of these periodicities to predicting ILI and influenza patterns through lognormal and gamma hurdle models. FINDINGS: During ten years of community surveillance, 66,799 ILI reports were collected covering 2.9 million patient visits; 2604 nasal swabs were collected 559 of which were PCR-positive for influenza virus. Both annual and nonannual cycles were detected in the ILI time series, with the annual cycle showing 8.9% lower ILI activity (95% CI: 8.8%-9.0%) from February 24 to May 15. Nonannual cycles had substantial explanatory power for ILI trends (DeltaAIC = 183) compared to all annual covariates (DeltaAIC = 263). Near-annual signals were observed for PCR-confirmed influenza but were not consistent along in time or across influenza (sub)types. INTERPRETATION: Our study reveals a unique pattern of respiratory disease dynamics in a tropical setting influenced by both annual and nonannual drivers. Timing of vaccination campaigns and hospital capacity planning may require a complex forecasting approach. FAU - Yang, Fuhan AU - Yang F AD - Department of Biology and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, United States. FAU - Servadio, Joseph L AU - Servadio JL AD - Department of Biology and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, United States. FAU - Le Thanh, Nguyen Thi AU - Le Thanh NT AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. FAU - Lam, Ha Minh AU - Lam HM AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. FAU - Choisy, Marc AU - Choisy M AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. AD - Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. FAU - Thai, Pham Quang AU - Thai PQ AD - National Institute of Hygiene and Epidemiology, Hanoi, Vietnam. FAU - Nhu Thao, Tran Thi AU - Nhu Thao TT AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. AD - Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, United States. FAU - Thao Vy, Nguyen Ha AU - Thao Vy NH AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. FAU - Phuong, Huynh Thi AU - Phuong HT AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. FAU - Nguyen, Tran Dang AU - Nguyen TD AD - Department of Biology and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, United States. AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. FAU - Hoai Tam, Dong Thi AU - Hoai Tam DT AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. FAU - Hanks, Ephraim M AU - Hanks EM AD - Department of Statistics and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, United States. FAU - Vinh, Ha AU - Vinh H AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. AD - Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. FAU - Bjornstad, Ottar N AU - Bjornstad ON AD - Department of Biology and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, United States. FAU - Van Vinh Chau, Nguyen AU - Van Vinh Chau N AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. AD - Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. FAU - Boni, Maciej F AU - Boni MF AD - Department of Biology and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, United States. AD - Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. AD - Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. LA - eng GR - WT_/Wellcome Trust/United Kingdom GR - F32 AI167600/AI/NIAID NIH HHS/United States GR - HHSN272201400007C/AI/NIAID NIH HHS/United States GR - INV-005517/GATES/Bill & Melinda Gates Foundation/United States PT - Preprint DEP - 20230329 PL - United States TA - medRxiv JT - medRxiv : the preprint server for health sciences JID - 101767986 UIN - BMJ Glob Health. 2023 Nov;8(11):. PMID: 37935520 PMC - PMC10081429 OTO - NOTNLM OT - Vietnam OT - influenza OT - influenza-like illness OT - mHealth OT - participatory epidemiology OT - syndromic surveillance OT - tropics COIS- Competing Interests The authors declare that they have no competing interests. EDAT- 2023/04/11 06:00 MHDA- 2023/04/11 06:01 PMCR- 2023/04/07 CRDT- 2023/04/10 04:12 PHST- 2023/04/11 06:00 [pubmed] PHST- 2023/04/11 06:01 [medline] PHST- 2023/04/10 04:12 [entrez] PHST- 2023/04/07 00:00 [pmc-release] AID - 2023.03.28.23287862 [pii] AID - 10.1101/2023.03.28.23287862 [doi] PST - epublish SO - medRxiv [Preprint]. 2023 Mar 29:2023.03.28.23287862. doi: 10.1101/2023.03.28.23287862.