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Cohort profile: the China Ageing REespiratory infections Study (CARES), a prospective cohort study in older adults in Eastern China
  1. Benjamin J Cowling1,
  2. Cuiling Xu1,2,3,
  3. Fenyang Tang4,
  4. Jun Zhang5,
  5. Jinjin Shen6,
  6. Fiona Havers7,
  7. Rachael Wendladt8,
  8. Nancy HL Leung1,
  9. Carolyn Greene7,
  10. A Danielle Iuliano7,
  11. Pat Shifflett8,
  12. Ying Song7,
  13. Ran Zhang7,
  14. Lindsay Kim7,
  15. Yuyun Chen1,
  16. Daniel KW Chu1,
  17. Huachen Zhu1,
  18. Yuelong Shu2,3,
  19. Hongjie Yu9,10,
  20. Mark G Thompson7
  21. on behalf of the CARES investigators
  1. 1 WHO Collaborating Centre for Infectious Disease Epidemiology and Control, Li Ka Shing Faculty of Medicine, School of Public Health, University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
  2. 2 Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Collaboration Innovation Center for Diagnosis and Treatment of Infectious Diseases, Chinese Center for Disease Control and Prevention, Beijing, China
  3. 3 Key Laboratory for Medical Virology, National Health and Family Planning Commission, Beijing, China
  4. 4 Jiangsu Provincial Center for Disease Prevention and Control, Nanjing, China
  5. 5 Suzhou Center for Disease Prevention and Control, Suzhou, China
  6. 6 Yancheng Center for Disease Prevention and Control, Yancheng, China
  7. 7 Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  8. 8 Abt Associates, Cambridge, Massachusetts, USA
  9. 9 School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
  10. 10 Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China
  1. Correspondence to Dr Benjamin J Cowling; bcowling{at}


Purpose This study was established to provide direct evidence on the incidence of laboratory-confirmed influenza virus and respiratory syncytial virus (RSV) infections in older adults in two cities in Jiangsu Province, China, and the potential impact of acute respiratory infections on frailty.

Participants The cohort was enrolled in Suzhou and Yancheng, two cities in Jiangsu Province in Eastern China. Between November 2015 and March 2016, we enrolled 1532 adults who were 60–89 years of age, and collected blood samples along with baseline data on demographics, general health, chronic diseases, functional status and cognitive function through face-to-face interviews using a standardised questionnaire. Participants are being followed weekly throughout the year to identify acute respiratory illnesses. We schedule home visits to ill participants to collect mid-turbinate nasal and oropharyngeal swabs for laboratory testing and detailed symptom information for the acute illness. Regular follow-up including face-to-face interviews and further blood draws will take place every 6–12 months.

Findings to date As of 3 September 2016, we had identified 339 qualifying acute respiratory illness events and 1463 (95%) participants remained in the study. Laboratory testing is ongoing.

Future plans We plan to conduct laboratory testing to estimate the incidence of influenza virus and RSV infections in older adults. We plan to investigate the impact of these infections on frailty and functional status to determine the association of pre-existing immune status with protection against influenza and RSV infection in unvaccinated older adults, and to assess the exposure to avian influenza viruses in this population.

  • Influenza
  • Respiratory Infections
  • Rsv
  • Disease Burden

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  • Contributors This project is a multinational collaboration between investigators in the USA, Hong Kong and mainland China, and has required substantial contributions from the coinvestigators. In terms of the specific contributions, the study protocol was designed by BJC and MGT and drafted by CX. Substantial input was provided by FT, JZ, JS, FH, RW, NHLL, CG, ADI, PS, YiS, YuS and HY on the study design in the planning phase in a series of meetings in the USA, Hong Kong and mainland China. The study instruments were prepared by CX and NHLL with input from BJC, FT, JZ, JS, FH, RW, CG, ADI, PS, YiS, RZ, LK, YC, YuS, HY and MGT. The laboratory testing protocols were developed by LK, DKWC and HZ. This cohort profile manuscript was drafted by BJC; the appendix sections were drafted by BJC, FH, RW, NHLL, CG, ADI, PS, YiS, RZ, LK, YC and MGT; and all authors provided critical review of the text and approved the final version.

  • Funding This study was financially supported by the Influenza Division of the US Centers for Disease Control and Prevention (contract no HHSD2002013M53890B: 200-2014-F-60406, ’The epidemiology and prevention of influenza virus infections in low- and middle-income countries'), initially through a research contract with Abt Associates and the University of Hong Kong for the first year, and subsequently through a cooperative agreement with the University of Hong Kong (grant no 1U01IP001064) for the second year. The Suzhou Centers for Disease Control and Prevention (CDC) and Yancheng CDC were contracted to carry out study activities, with the support from China CDC at the national level and Jiangsu CDC at the provincial level. Principal investigators and coinvestigators from US CDC and Abt have made substantial contributions to the design of the study protocol and instruments.

  • Competing interests BJC has received research funding from Sanofi Pasteur. The authors report no other potential conflicts of interest.

  • Ethics approval The study protocol received ethical approval from the Institutional Review Board of the University of Hong Kong (Ref: UW15 404), and the Ethics Committee of Jiangsu Provincial Center for Disease Prevention and Control (Ref: JSJK2015-B013-02).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement We intend to make data freely available in the public domain after publication of major findings. Researchers interested in collaborations should contact the principal investigators, BJC ( and MGT ( We are keen to obtain full value from our cohorts and would welcome proposals to use this cohort from potential collaborators or from researchers interested in investigating specific questions independently.

  • Collaborators CARES investigators also include Vicky J Fang, Yi Guan, Chi Kin Lam, Qian Xiong and JS Malik Peiris (the University of Hong Kong); Min Levine and Brett Whitaker (US CDC); William Campbell (Abt Associates); Qigang Dai (Jiangsu CDC); Lin Luan, Benfeng Zheng and Yu Xia (Suzhou CDC); Renjie Jiang, Hongjun Zhang and Guoqing Chen (Yancheng CDC); and Luzhao Feng and Jiandong Zheng (China CDC).

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