Research Project on the Interaction Between Immune Function and Infectious Diseases in Older Adults and the Development of Prevention and Control Strategies

As population aging accelerates, infectious diseases have become a major factor affecting the health, quality of life, and survival outcomes of older adults. Immunosenescence, chronic low-grade inflammation (inflammaging), and dysbiosis of the respiratory and gut microbiota are considered important mechanisms underlying increased susceptibility to infection and a higher risk of severe disease in older adults. However, the interactions among these factors and their impact on infection-related outcomes remain incompletely understood.

Building upon a previously established pilot cohort of older adults, this study aims to further identify and validate key biological characteristics and risk factors associated with infectious diseases through large-scale population follow-up. A large prospective cohort of older adults will be established, while retrospective healthcare data collected since 2019 will also be integrated. Demographic information, comorbidities, medication history, infection-related clinical data, and biological specimens, including blood, urine, fecal, and respiratory samples, will be collected for long-term longitudinal follow-up. By integrating immunological assessments, immune repertoire analyses, microbiome profiling, and other multi-omics technologies, this study will systematically evaluate the effects of immunosenescence, respiratory and gut microbiome alterations, and environmental and climatic factors on the occurrence, severity, and prognosis of infectious diseases in older adults. The study aims to identify key biomarkers and microbial signatures associated with infection risk and to develop risk prediction and early warning models for infectious diseases in older adults, thereby providing scientific evidence for precision prevention, optimized clinical management, and public health decision-making in aging populations.

Study Overview

• Status: Not yet recruiting
• Conditions: Aging; Infectious Diseases; Immunosenescence

• Study Type: Observational
• Enrollment (Estimated): 23000

Contacts and Locations

• Study Contact: Name: Jingwen Ai; Phone Number: 17317958269; Email: jingwenai1990@126.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Adults aged 60 years and older

Description

Inclusion Criteria:

- General Cohort Inclusion Criteria

1. Adults aged 60 years or older who are in generally good health, defined as having no severe organ dysfunction that significantly affects daily living activities (e.g., decompensated heart, liver, or kidney failure), adequate nutritional status (without significant wasting or malnutrition), and the ability to communicate and comply with study procedures.
2. Male or female.
3. Able to understand the study and voluntarily provide written informed consent.

Infection Cohort Inclusion Criteria

1. Adults aged 60 years or older, regardless of sex.
2. Patients with an infectious disease diagnosed by a qualified clinician.

Exclusion Criteria:

• General Cohort Exclusion Criteria

  1. Refusal to participate in this study.
  2. Any other condition that, in the opinion of the investigator, makes the participant unsuitable for enrollment.

Infection Cohort Exclusion Criteria

1. Final primary diagnosis is a non-infectious disease (e.g., connective tissue disease, malignancy, or other non-infectious conditions).
2. Positive culture results determined by the treating clinician to represent colonization or contamination rather than true infection.
3. Refusal to participate in this study.
4. Critically ill patients or those unable to cooperate with specimen collection procedures.
5. Any other condition that, in the opinion of the investigator, makes the participant unsuitable for enrollment.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Older Adults Without Infection; Community-dwelling adults aged 60 years and older who do not develop any clinically diagnosed infectious disease during the follow-up period.
Older Adults With Infection; Community-dwelling adults aged 60 years and older who develop clinically diagnosed infectious diseases during follow-up.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Occurrence of infectious disease outcomes in older adults	Occurrence of infectious disease outcomes in older adults, including all-cause mortality, infection-related mortality, first infectious disease event, and progression to severe infection.	Baseline to 3 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
High-Frequency Infection Status (≥6 Infections per Year)	Defined as an average of six or more infectious episodes per year during follow-up.	Baseline to 3 Years
Pathogen-Specific Infection Events	Infectious disease events caused by specific pathogens, used to evaluate pathogen distribution and temporal trends.	Baseline to 3 Years
Changes in Immune Function Biomarkers	Assessment of longitudinal changes in immune cell subsets and immune function status.	Baseline to 3 Years

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Metabolomic and Microbiome Profiles	Assessment of longitudinal changes in metabolomic profiles and gut and respiratory microbiome characteristics associated with infection risk and disease severity.	Baseline to 3 Years

Collaborators and Investigators

• Sponsor: Huashan Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 9, 2026
• Primary Completion (Estimated): December 30, 2029
• Study Completion (Estimated): December 30, 2029

Study Registration Dates

• First Submitted: June 8, 2026
• First Submitted That Met QC Criteria: June 8, 2026
• First Posted (Actual): June 12, 2026

Study Record Updates

• Last Update Posted (Actual): June 12, 2026
• Last Update Submitted That Met QC Criteria: June 8, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Disease Attributes; Infections; Pathological Conditions, Signs and Symptoms; Communicable Diseases
• Other Study ID Numbers: 20260306-001

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No