# Influence of SARS-CoV-2 reinfection on bone health in the population over 55 years old in Beijing, China: a cross-sectional study

## TL;DR

This study finds that older adults in Beijing who experienced SARS-CoV-2 reinfection had a significantly higher risk of osteoporosis compared to those with a single infection.

## Contribution

The study is the first to demonstrate a strong association between SARS-CoV-2 reinfection and increased osteoporosis risk in individuals over 55 years old.

## Key findings

- Individuals with SARS-CoV-2 reinfection had a 48.3% prevalence of osteoporosis compared to 17.3% in those with a single infection.
- Reinfection was significantly linked to higher osteoporosis rates at the hip and lumbar spine after adjusting for confounding factors.
- The odds ratio for osteoporosis in reinfection cases was 3.08, indicating a strong independent association.

## Abstract

Despite the global prevalence of SARS-CoV-2 reinfection, relatively little is known regarding its association with osteoporosis in older adults. This study investigated the potential impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on bone health or osteoporosis risk in adults aged 55 years and older in Beijing, China, while also exploring additional factors that may influence this association.

This cross-sectional study was conducted at Beijing Ditan Hospital, Beijing, China, between August and December 2024. Patients aged ≥ 55 years with SARS-CoV-2 infections were included. Data on demographic characteristics, lifestyle habits, diet, serum contents of 25-hydroxyvitamin D (25-OH-VD), and other potential risk factors for osteoporosis were collected through structured questionnaires. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry (DXA). To identify the variables associated with osteoporosis, logistic regression analysis was employed.

Three hundred and eighty-eight patients were enrolled, comprising 272 individuals with a single SARS-CoV-2 infection and 116 with two or more infections. The results revealed that individuals who had reinfection revealed a considerably higher prevalence of osteoporosis (48.3% vs. 17.3%, p < 0.0001). This trend was consistent across different skeletal sites: 33.6% vs. 7.4% at the left hip, 37.9% vs. 5.5% at the right hip (p < 0.0001), and 30.2% vs. 12.9% at the lumbar spine (L1–L4) (p < 0.0001). SARS-CoV-2 reinfection remained substantially associated with osteoporosis after controlling for con-founding variables, with an OR of 3.08 (95% CI: 1.696–5.593).

In summary, the risk of osteoporosis among individuals with SARS-CoV-2 reinfection should be carefully monitored, and greater emphasis should be placed on early, individualized prevention and treatment strategies.