Beyond the pandemic declaration: Persistent daily health complaints in diabetic COVID-19 survivors and the protective effect of prior vaccination in Indonesian primary care

Technical Summary: Persistent Daily Health Complaints in Diabetic COVID-19 Survivors and the Protective Effect of Prior Vaccination

Problem Statement
While the acute phase of the COVID-19 pandemic has receded, a significant public health crisis persists in the form of "Long COVID," defined by the WHO as symptoms affecting daily life that begin three months post-infection and last at least two months. Patients with Diabetes Mellitus (DM) are identified as a high-risk group for severe outcomes and persistent post-infection sequelae. However, evidence regarding the specific burden of persistent daily health complaints among diabetic survivors in Low- and Middle-Income Country (LMIC) primary care settings remains limited. Existing literature largely focuses on hospitalized cohorts from high-income countries or simply the presence of symptoms rather than quantifying the volume of daily health issues. Furthermore, the specific role of pre-infection vaccination in mitigating these persistent complaints, distinct from mortality reduction, is understudied in LMIC contexts where primary health centers (Puskesmas) serve as the frontline for chronic disease management.

Methodology
This study employed a cross-sectional design conducted between March and August 2024 in 45 community health centers (Puskesmas) in Yogyakarta Province, Indonesia.

• Participants: The analytic sample consisted of 420 adults (aged ≥15 years) with a confirmed diagnosis of diabetes mellitus and a self-reported history of COVID-19 infection.
• Data Collection: Trained enumerators conducted face-to-face interviews using a structured 25-item checklist of daily health complaints. Vaccination status was rigorously verified against electronic records (SatuSehat) and physical cards.
• Outcome Measures: The 25 complaints were categorized into three domains based on the WHO's International Classification of Functioning, Disability and Health (ICF): Sensory Function/Pain, Body System Function, and Activity Participation. The primary outcome was the total count of health complaints (range 0–25).
• Statistical Analysis: Due to overdispersion in the count data (variance-to-mean ratio >1), negative binomial regression was used to model the outcomes. The analysis was adjusted for sociodemographic and clinical variables. Missing data (<2%) were handled using K-nearest neighbours (KNN) imputation (k=5). A sensitivity analysis using complete case data confirmed the robustness of the findings.

Key Contributions

• Contextual Novelty: This is the first community-based study in an LMIC primary care setting to quantify the number of persistent daily health complaints specifically among diabetic COVID-19 survivors, addressing a gap in data for populations often underrepresented in hospital-based research.
• Granular Outcome Measurement: Unlike studies focusing solely on the binary presence of Long COVID, this research utilizes a 25-item checklist to measure the burden (count) of symptoms across functional domains.
• Vaccination Timing Analysis: The study distinguishes between vaccination status prior to infection, vaccination following infection, and never-vaccinated status, providing nuanced data on the timing of immunization relative to the index infection.

Results

• Demographics: The median age of participants was 60 years, with 70.2% female. At the time of their COVID-19 infection, only 36.2% of participants had been vaccinated; 63.8% were unvaccinated (55.0% vaccinated after infection, 8.8% never vaccinated).
• Symptom Prevalence: The most common complaints were joint/muscle pain (46.0%), visual impairment (43.1%), and fatigue (24.3%). Participants reported a median of 3 post-COVID health issues.
• Vaccination Impact: In multivariable negative binomial regression, individuals who were never vaccinated had a 45% higher rate of total health complaints compared to those vaccinated before infection (Incidence Rate Ratio [IRR] = 1.45; 95% CI 1.10–1.91).
• Other Risk Factors:
  • Female Sex: Associated with higher rates of total complaints (IRR = 1.25), sensory/pain symptoms, and activity limitations.
  • Education: Secondary education was associated with lower body system dysfunction (IRR = 0.66).
  • Comorbidities: The absence of other comorbidities was associated with fewer sensory/pain complaints (IRR = 0.84).
  • Post-Infection Vaccination: Vaccination administered after the infection showed no significant protective effect against the persistent symptoms of that specific infection episode (IRR = 1.06; 95% CI 0.90–1.26).
  • Hospitalization: History of hospitalization was not significantly associated with complaint counts, likely due to low statistical power (only 14 hospitalized patients) and potential survival bias.

Significance and Claims
The paper asserts that pre-infection COVID-19 vaccination is strongly associated with a substantially reduced burden of persistent daily health complaints in diabetic patients. The authors claim that this finding supports a dual strategy for LMIC primary care: promoting pre-infection vaccination as part of routine chronic disease management and ensuring timely post-infection follow-up.

The study modestly concludes that while the cross-sectional design precludes definitive causal inference, the observed risk gradient (never vaccinated > vaccinated after infection > vaccinated before infection) and biological plausibility support the protective association of pre-infection vaccination. The authors emphasize that integrating vaccination promotion into routine diabetes care at the primary care level in LMICs may be a critical intervention to reduce long-term morbidity and functional impairment. They explicitly state that future prospective studies with uninfected control groups and serological confirmation are necessary to confirm causality.