Changes in Hospitalizations for Respiratory Diseases Following the COVID-19 Epidemic
The COVID-19 pandemic has significantly reshaped global health dynamics, not only through direct infections but also via the implementation of widespread nonpharmaceutical interventions (NPIs). This study examined how these measures—including mask-wearing, hand hygiene, physical distancing, and reduced gatherings—impacted hospitalization patterns for respiratory diseases beyond SARS-CoV-2 infection at a major tertiary hospital in Western China. By comparing pre-pandemic (2019) and post-pandemic (2020) data, the analysis revealed notable shifts in the epidemiology of respiratory conditions, offering insights into the broader implications of NPIs on public health.
Study Design and Patient Characteristics
This single-center observational study evaluated 15,175 patients admitted to the Department of Pulmonary and Critical Care Medicine (PCCM) at West China Hospital, Sichuan University, over two years (January 2019–December 2020). The cohorts were stratified into age groups: young (18–44 years), middle-aged (45–59 years), older (60–74 years), elderly (75–89 years), and longevity (≥90 years). Demographic characteristics, including average age (59 years) and sex distribution, showed no significant differences between the pre- and post-pandemic groups (P > 0.05). However, the proportion of young and elderly patients decreased slightly in 2020, while thoracic malignant tumors remained the most prevalent diagnosis (46.4% in 2019 vs. 49.1% in 2020).
Impact on Infectious Respiratory Diseases
The most striking changes occurred in the incidence of infectious respiratory diseases. Pulmonary infections decreased from 25.0% (1,936/7,746) of total admissions in 2019 to 21.4% (1,590/7,429) in 2020. This decline was driven by reductions in viral and bacterial pneumonia cases.
Viral Pneumonia
Influenza infections showed the most dramatic declines. Influenza A (H1N1) cases dropped from 122 to 2, H3N2 from 16 to 2, and influenza B from 9 to 4. Adenovirus pneumonia cases fell from 6 to 0, and influenza-related deaths decreased from 13 to 1. Monthly trends confirmed year-round reductions in influenza cases post-pandemic (Supplementary Figure 1A). Diagnostic methods, including nucleic acid testing for Epstein-Barr virus and cytomegalovirus, as well as metagenomic next-generation sequencing of respiratory samples, ensured accurate viral identification.
Bacterial Pneumonia
Bacterial pneumonia admissions decreased from 9.1% (708/7,746) to 7.8% (578/7,429). While the study did not specify bacterial pathogens, clinical diagnoses indicated consistent reductions across all months post-outbreak (Supplementary Figure 1F).
Fungal Infections
Pulmonary aspergillosis and mucormycosis cases trended downward, though these changes lacked statistical significance. Monthly data revealed slight increases in Aspergillus infections during June–August 2020 (Supplementary Figure 1B). Tuberculosis (TB) admissions remained stable, reflecting the limited impact of NPIs on TB transmission, which requires targeted public health strategies.
Noninfectious Respiratory Diseases
Acute Exacerbations of Chronic Obstructive Pulmonary Disease (AECOPD)
AECOPD admissions decreased significantly from 6.8% (529/7,746) to 5.4% (403/7,429) (χ² = 13.280, P < 0.001). Monthly data showed consistent reductions except in June and July 2020 (Supplementary Figure 1D). NPIs likely reduced exposure to environmental triggers and respiratory pathogens that precipitate exacerbations.
Bronchiectasis
While overall bronchiectasis admissions remained stable, cases complicated by infection declined from 2.1% (165/7,746) to 1.5% (109/7,429) (χ² = 5.448, P = 0.020). Monthly trends mirrored AECOPD patterns, with reductions in all months except August 2020 (Supplementary Figure 1E).
Interstitial Lung Disease (ILD)
ILD admissions decreased from 5.1% (393/7,746) to 4.2% (315/7,429) (χ² = 6.510, P = 0.011). This reduction may reflect improved avoidance of environmental irritants or delayed hospital visits due to pandemic-related fears.
Mechanisms and Public Health Implications
The observed declines in respiratory infections align with the known efficacy of NPIs in reducing pathogen transmission. Mask-wearing disrupts airborne spread of viruses like influenza, while hand hygiene reduces contact with contaminated surfaces. Physical distancing limits person-to-person transmission, particularly in crowded settings. These measures collectively reduced the burden of respiratory infections, as evidenced by the near-elimination of influenza cases and decreased bacterial pneumonia admissions.
For noninfectious diseases like AECOPD and bronchiectasis, reduced exposure to pollutants, allergens, and infectious agents likely contributed to fewer exacerbations. However, the stability of TB cases underscores the need for pathogen-specific strategies, such as enhanced screening and treatment adherence programs.
Limitations and Future Directions
This study’s single-center design and focus on hospitalized patients limit generalizability. Outpatient data and asymptomatic cases were not captured, potentially underestimating the true impact of NPIs. Additionally, bacterial pneumonia diagnoses lacked pathogen confirmation, highlighting the need for future studies with microbiological data.
Multicenter studies with larger cohorts are necessary to validate these findings and explore long-term trends. The persistence of beneficial behaviors, such as mask-wearing in high-risk settings, could sustain reductions in respiratory disease morbidity beyond the pandemic.
Conclusion
The COVID-19 pandemic inadvertently provided a natural experiment on the effectiveness of NPIs in curbing respiratory diseases. Significant declines in influenza, bacterial pneumonia, and chronic disease exacerbations demonstrate the dual benefits of these measures. Sustaining mask use, hand hygiene, and social distancing in vulnerable populations and high-density areas could reduce the global burden of respiratory illnesses. Conversely, TB’s resilience highlights the need for tailored interventions. As the world transitions to post-pandemic norms, integrating these practices into public health policies offers a pathway to mitigate future outbreaks and improve respiratory health outcomes.
doi.org/10.1097/CM9.0000000000001871
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