Post-COVID lung microbes stay healthy

New research shows the lung microbiome in patients with post-COVID residual lung changes is similar to healthy lungs and distinct from pulmonary fibrosis, offering insights into recovery and long-term lung health.

Many people who had COVID-19 are left with residual lung changes – areas of the lung that look abnormal on scans – even months after infection. Experts have wondered whether these changes might lead to long-term lung damage, similar to conditions like idiopathic pulmonary fibrosis (IPF).

A new study from the UK Interstitial Lung Disease (UKILD) consortium and the POSTCODE team investigated whether the lung microbiome (bacteria living in our airways) might play a role in these post-COVID lung changes. Breathing Matters-funded researchers contributed to this study.

Using advanced testing on lung fluid samples from patients about a year after COVID-19 infection, researchers compared their lung bacteria with people who have IPF, fibrotic hypersensitivity pneumonitis (fHP), and healthy volunteers.

Key Findings:

• Healthy microbiome: People with post-COVID lung changes had a lung microbiome similar to healthy individuals.
• Different from fibrotic disease: Their lung bacteria were clearly different from those in IPF, which is associated with harmful changes in the microbiome.
• No link to severity: The types or amounts of bacteria did not seem to influence the severity of lung changes or how well patients recovered.
• Dominant bacteria: Some bacteria like Streptococcus were slightly more abundant, but this did not affect recovery.

What This Means for Patients:

• Good news: Post-COVID lung changes do not appear to be caused by harmful bacterial shifts in the lungs.
• No major long-term infection risk: The microbiome is not likely contributing to lung damage after COVID-19.
• Hope for recovery: This supports the idea that most post-COVID lung changes may gradually improve over time without the complications seen in serious fibrotic diseases, seen in IPF.

Next Steps in Research:

Researchers recommend continued monitoring and long-term imaging studies to track lung recovery, but this study suggests that bacterial imbalance is not a driver of post-COVID lung problems.

Conclusion:

If you are living with lingering lung changes after COVID-19, this research is reassuring – your lung bacteria are likely healthy, and your recovery may follow a natural course. Ongoing research will continue to explore the best ways to support lung health after COVID-19.

Full article: ERJ Open Research 2025 11(3): 00826-2024

[Posted February 2026]