Study findings updated . AI-assisted evidence summary, not individual medical advice or a clinician endorsement.
THE SHORT VERSION
What’s worth knowing.
The key findings, what they mean, and the context that matters.
THE HEADLINE TAKEAWAYAbout 1 in 36 sparedPer 36 hospital patients given dexamethasone, about 1 more was alive at 28 days
Steroid dexamethasone lowered COVID deaths, most among ventilated patients.
In a large UK randomized trial of people hospitalized with COVID-19, 22.9% of those given the steroid dexamethasone died within 28 days, versus 25.7% of those given usual care. The gain was largest for patients on a breathing machine (29.3% vs 41.4% died). Patients who needed no extra oxygen saw no clear benefit (17.8% vs 14.0%).
The trial showed that calming the body's inflammatory response saves lives once COVID pneumonia is starving patients of oxygen. It also showed timing matters: patients who did not yet need oxygen did not benefit. Open-label trial (everyone knew who got the drug) run in early 2020, before vaccines and other treatments changed who ends up in hospital.
See the evidence
The RECOVERY trial randomly assigned 6425 patients hospitalized with COVID-19 in the UK, March to June 2020, to dexamethasone for up to 10 days or usual care.
From the study: “Overall, 482 patients (22.9%) in the dexamethasone group and 1110 patients (25.7%) in the usual care group died within 28 days after randomization”
About 1 in 36 spared
RECOVERY Collaborative Group et al. Dexamethasone in Hospitalized Patients with Covid-19. The New England journal of medicine. 2021.
From the study: “but not among those who were receiving no respiratory support at randomization (17.8% vs. 14.0%; rate ratio, 1.19; 95% CI, 0.92 to 1.55)”
About 1 in 36 spared
RECOVERY Collaborative Group et al. Dexamethasone in Hospitalized Patients with Covid-19. The New England journal of medicine. 2021.
About 1 in 14 US lung transplants went to COVID lung failure.
1 in 14 lung transplantsUS lung transplants done for COVID lung failure, Aug 2020 to Sept 2021
Of 3039 lung transplants in the US national registry from August 2020 to September 2021, 214 (7.0%) were for COVID-19 lung failure: 140 for acute respiratory distress syndrome (severe whole-lung injury) and 74 for lung scarring. Before surgery, 64.5% were on ECMO, a machine that oxygenates blood outside the body. At three months, 95.6% were alive.
For a small group of patients, COVID wrecked the lungs beyond repair and new lungs were the only way out. Early survival approached that of other lung transplant patients, and the authors say transplant may be acceptable for carefully chosen patients. Registry data with a median follow-up of just 1.9 months, so long-term survival after these transplants is unknown.
See the evidence
An analysis of the US national transplant registry (UNOS) covering every reported lung transplant from August 2020 through September 2021.
From the study: “Of 3039 lung transplantations, 214 (7.0%) were performed for Covid-19–related respiratory failure”
1 in 14 lung transplants
Roach A et al. Lung Transplantation for Covid-19-Related Respiratory Failure in the United States. The New England journal of medicine. 2022.
More than one-third still had lung abnormalities on CT two years later.
39% still abnormalHad lung abnormalities on CT at 2 years, among patients not healed at discharge
Of 144 people hospitalized with COVID-19 in early 2020 whose lungs had not cleared by discharge, 39% still had abnormal patches on chest CT 2 years later. Milder, non-scarring patches faded, from 31% at 6 months to 16%, but scar-like (fibrotic) changes held steady at 23%. The other 61% had fully clear scans.
Scar-like changes matter because they may be permanent. Compared with people whose scans cleared, those with leftover patches more often had breathing symptoms (34% vs 15%) and reduced oxygen transfer into the blood (43% vs 20%). Only 144 mostly severe patients chosen because their lungs had not healed by discharge, so 39% is not the rate for all patients; a separate Wuhan study found leftover marks tiny by year three.
See the evidence
A prospective study in China following 144 adults discharged after COVID-19 in early 2020, with repeat CT scans and lung tests at 6 months, 12 months and 2 years.
From the study: “On 2-year follow-up CT scans, 39% of participants (56 of 144) had ILAs, including 23% (33 of 144) with fibrotic ILAs and 16% (23 of 144) with nonfibrotic ILAs.”
39% still abnormal
Han X et al. Longitudinal Assessment of Chest CT Findings and Pulmonary Function after COVID-19 Infection. Radiology. 2023.
Most breathless long COVID patients had lungs that tested normal.
Only 1 in 8Breathless long COVID patients whose tests hinted at a lung cause
In 109 breathless people with long COVID who were never hospitalized, a special MRI that tracks inhaled xenon gas passing into the blood looked no different from 44 healthy controls or 43 long COVID patients without breathlessness. More than 90% of standard lung test values were in the normal range. Only 14 of the 109 had low gas transfer plus subtle MRI changes.
Breathlessness after a mild infection is real, but in most people this study could not trace it to damaged lung tissue, even with an advanced scanner. A small group, about 1 in 8, may have a true lung cause. A UK study of mostly white, vaccinated volunteers scanned a median 632 days after infection; it cannot rule out problems outside the lungs or damage too small to detect.
See the evidence
A multicenter UK study comparing xenon lung MRI, breathing tests and questionnaires in 196 people: 109 breathless and 43 non-breathless long COVID patients and 44 healthy controls.
From the study: “A subset of BLC participants with low T L CO (14 out of 109) showed reduced 129 Xe-MRI metrics and higher breathlessness scores.”
Only 1 in 8
Ng, Kher Lik et al.. Using hyperpolarised xenon magnetic resonance imaging to explore breathlessness in long COVID: results from the EXPLAIN study.. ERJ open research. 2026.
From the study: “though >90% of values remained within normal range”
Only 1 in 8
Ng, Kher Lik et al.. Using hyperpolarised xenon magnetic resonance imaging to explore breathlessness in long COVID: results from the EXPLAIN study.. ERJ open research. 2026.
From the study: “No significant differences in global or regional RBC:M or RBC:Gas were observed across groups.”
Only 1 in 8
Ng, Kher Lik et al.. Using hyperpolarised xenon magnetic resonance imaging to explore breathlessness in long COVID: results from the EXPLAIN study.. ERJ open research. 2026.
Lying face-down while awake kept some patients off ventilators.
About 1 in 15One fewer breathing tube or death for every 15 patients who lay face-down
In a trial of 1121 adults with severe COVID pneumonia on high-flow oxygen, 40% of those asked to lie on their stomach while awake needed a breathing tube or died within 28 days, versus 46% given standard care. Fewer needed a breathing tube (33% vs 40%). Deaths alone were not clearly different (21% vs 24%).
A free, low-tech position change reduced the need for breathing tubes. Patients who spent at least 8 hours a day face-down did best (17% failure vs 48%), though that comparison was not randomized. Patients and staff knew who was lying face-down, and the trial showed fewer intubations but no clear drop in deaths.
See the evidence
Six linked randomized trials in Mexico, France, the USA, Spain, Ireland and Canada enrolled 1126 hospitalized adults on high-flow oxygen in 2020 and 2021.
From the study: “Treatment failure occurred in 223 (40%) of 564 patients assigned to awake prone positioning and in 257 (46%) of 557 patients assigned to standard care”
About 1 in 15
Ehrmann S et al. Awake prone positioning for COVID-19 acute hypoxaemic respiratory failure: a randomised, controlled, multinational, open-label meta-trial. The Lancet. Respiratory medicine. 2021.
From the study: “The number needed to treat to avoid one treatment failure was 15”
About 1 in 15
Ehrmann S et al. Awake prone positioning for COVID-19 acute hypoxaemic respiratory failure: a randomised, controlled, multinational, open-label meta-trial. The Lancet. Respiratory medicine. 2021.
From the study: “Treatment failure occurred in 25 (17%) of 151 patients who remained in awake prone positioning for at least 8 h daily on average”
About 1 in 15
Ehrmann S et al. Awake prone positioning for COVID-19 acute hypoxaemic respiratory failure: a randomised, controlled, multinational, open-label meta-trial. The Lancet. Respiratory medicine. 2021.
COPD was linked to higher COVID death risk, but asthma was not.
54% higher death riskHazard ratio for COVID death, people with COPD vs without; asthma showed no rise
Among more than eight million adults registered with English family doctors in early 2020, people with COPD (a long-term lung disease that narrows the airways) had a 54% higher risk of dying from COVID-19 than people without COPD, after accounting for age, weight, smoking and other illnesses. People with asthma had no higher death risk (hazard ratio 0.99), even those with severe asthma.
Asthma, the most common lung disease in the study (13.2% of adults), was not linked to dying of COVID. COPD carried a real but modest extra risk, which the authors note was mostly far below these patients' ordinary risk of death from any cause. Observational records from England's first wave (January to April 2020), before vaccines, so the findings show links, not cause.
See the evidence
A population study linking records from 1205 English general practices to COVID tests, hospital admissions and deaths between January and April 2020.
From the study: “Having COPD was associated with a 54% (HR 1·54 [95% CI 1·42–1·67]) increase in the risk of death due to COVID-19 in the fully adjusted model”
54% higher death risk
Aveyard P et al. Association between pre-existing respiratory disease and its treatment, and severe COVID-19: a population cohort study. The Lancet. Respiratory medicine. 2021.
From the study: “whereas there was no evidence that people with asthma were at an increased risk of death (0·99 [0·91–1·07])”
54% higher death risk
Aveyard P et al. Association between pre-existing respiratory disease and its treatment, and severe COVID-19: a population cohort study. The Lancet. Respiratory medicine. 2021.
Mild COVID was not linked to lost lung function in young adults.
243 cases, no lung lossMild COVID in young adults: no lung function drop vs uninfected peers
In a Swedish group of 853 young adults (median age 25.9) who had breathing tests before and after the pandemic began, the 243 with antibodies showing past infection, mostly mild, had the same change in lung function as the 607 without antibodies. Results were similar in people with asthma.
Many people wonder whether a mild bout of COVID quietly harmed their lungs. Because these young adults had lung tests on file from before the pandemic, researchers could compare each person with themselves, and found no lasting dip. Only one infected participant was hospitalized, and the tests measured airflow rather than oxygen transfer, so it cannot speak to severe illness or older adults.
See the evidence
A Stockholm birth-cohort study comparing spirometry from 2016 to 2019 with repeat tests in 2020 to 2021 in 853 young adults, using antibody tests to identify past infection.
From the study: “Of the 853 included participants, 29% (n = 243) were seropositive.”
243 cases, no lung loss
Mogensen I et al. Lung function before and after COVID-19 in young adults: A population-based study. The journal of allergy and clinical immunology. Global. 2022.
From the study: “In total, 29% of the participants were seropositive (n = 243) and 71% were seronegative (n = 607) for SARS-CoV-2 antibodies.”
243 cases, no lung loss
Mogensen I et al. Lung function before and after COVID-19 in young adults: A population-based study. The journal of allergy and clinical immunology. Global. 2022.
From the study: “We found no evidence of mild-to-moderate COVID-19 affecting lung function long term in a population-based cohort of young adults.”
243 cases, no lung loss
Mogensen I et al. Lung function before and after COVID-19 in young adults: A population-based study. The journal of allergy and clinical immunology. Global. 2022.
Three years after hospital, survivors' lung function matched uninfected people.
3 years laterLung function in COVID hospital survivors matched people never infected
Among 1359 people discharged after COVID-19 from a Wuhan hospital in early 2020, a sample given breathing tests at 3 years had lung function similar to matched community members who never had COVID. Scans still showed thin lines and small widened airways in some, but these marks took up only 0.2-0.3% of the lungs. Still, 54% reported at least one lingering symptom.
It is one of the longest looks at COVID lungs, and it suggests that for most hospital survivors lung function recovers with time, even when scans still show traces. Lingering symptoms were common but mostly mild to moderate. A single-hospital study in Wuhan where only a subset had lung tests, so it may not reflect people with the most severe lung injury.
See the evidence
A single-center cohort in Wuhan, China, following 1359 survivors discharged in early 2020 through a 3-year visit in early 2023, with matched uninfected community controls.
From the study: “Lung function of survivors at 3 years was similar to that of matched community controls.”
3 years later
Zhang H et al. 3-year outcomes of discharged survivors of COVID-19 following the SARS-CoV-2 omicron (B.1.1.529) wave in 2022 in China: a longitudinal cohort study. The Lancet. Respiratory medicine. 2024.
From the study: “but the volume ratio of lung lesion to total lung was only 0·2-0·3%”
3 years later
Zhang H et al. 3-year outcomes of discharged survivors of COVID-19 following the SARS-CoV-2 omicron (B.1.1.529) wave in 2022 in China: a longitudinal cohort study. The Lancet. Respiratory medicine. 2024.
From the study: “Of 1359 COVID-19 survivors who completed 2-year and 3-year follow-up, 728 (54%) had at least one sequelae symptom at 3 years after symptom onset and before omicron infection”
3 years later
Zhang H et al. 3-year outcomes of discharged survivors of COVID-19 following the SARS-CoV-2 omicron (B.1.1.529) wave in 2022 in China: a longitudinal cohort study. The Lancet. Respiratory medicine. 2024.
Clinic recruits reported symptoms despite generally preserved lung function
760/963 (79%)
At the first follow-up, 760/963 (79%) of the included post-COVID clinic recruits reported breathing-related symptoms. Overall lung function was generally preserved.
A measure of gas transfer through the lungs (DLCO) was lower in those with symptoms than those without them. This summary does not explain what its test percentages represent, so they are omitted. The symptom percentage describes included clinic recruits.
Earlier breathing-related symptoms were linked to later reports of symptoms
In the group recruited through the clinic, breathing-related symptoms at the first follow-up were linked to being in the breathing-symptom group at the second follow-up.
The comparison group is not given here, so the numerical odds are omitted. This link does not tell an individual their chance of having lasting symptoms.
Study details & original results
Hallberg, Carl et al.. Respiratory symptoms up to 18 months after COVID-19 - a longitudinal observational study.. Respiratory research. 2026.
Prevalence of self-reported respiratory symptoms at the first follow-up among included participants recruited through a post-COVID clinic
760/963 (79%)
DLCO in participants with versus without respiratory symptoms; overall lung function was generally preserved
Most lung-test values were normal in Long COVID participants with breathlessness
Long COVID participants with breathlessness had lower lung-test scores than controls. Even so, more than 90% of their measured values were within the normal range.
The percentage counts measured values, not people whose whole assessment was normal. The result does not explain why the participants felt breathless.
Lung tests suggested a possible contribution to breathlessness in one group
Among Long COVID participants never hospitalized and with otherwise unexplained breathlessness, 14/109 (~13%) had low lung gas-transfer results. They also had lower gas-exchange measurements on xenon MRI and higher breathlessness scores.
The comparison groups for the MRI and breathlessness scores are not given here. These findings suggest only a possible lung contribution in this subgroup, not an established explanation for everyone’s breathlessness.
Study details & original results
Ng, Kher Lik et al.. Using hyperpolarised xenon magnetic resonance imaging to explore breathlessness in long COVID: results from the EXPLAIN study.. ERJ open research. 2026.
Although breathless long-COVID participants had lower FEV1, FVC, TLCO, and KCO z-scores than controls, more than 90% of the measured values remained within the normal range.
Among never-hospitalised long-COVID participants with otherwise unexplained breathlessness, approximately 13% had low TLCO and showed reduced xenon-MRI gas-exchange metrics and higher breathlessness scores, suggesting only a potential pulmonary contribution in this subgroup.
Ng, Kher Lik et al.. Using hyperpolarised xenon magnetic resonance imaging to explore breathlessness in long COVID: results from the EXPLAIN study.. ERJ open research. 2026.
Among never-hospitalised long-COVID participants with otherwise unexplained breathlessness, approximately 13% had low TLCO and showed reduced xenon-MRI gas-exchange metrics and higher breathlessness scores, suggesting only a potential pulmonary contribution in this subgroup.
Although breathless long-COVID participants had lower FEV1, FVC, TLCO, and KCO z-scores than controls, more than 90% of the measured values remained within the normal range.
Browse the 10 original sourcesThe complete bibliography behind this monitor.
[1]
Zhang, Zhijin et al.. Longitudinal profiling of upper respiratory tract microbiota and metabolome in hospitalized COVID-19 convalescents: a 3-year prospective cohort study.. Journal of translational medicine. 2026.
Ng, Kher Lik et al.. Using hyperpolarised xenon magnetic resonance imaging to explore breathlessness in long COVID: results from the EXPLAIN study.. ERJ open research. 2026.
Ehrmann S et al. Awake prone positioning for COVID-19 acute hypoxaemic respiratory failure: a randomised, controlled, multinational, open-label meta-trial. The Lancet. Respiratory medicine. 2021.
Aveyard P et al. Association between pre-existing respiratory disease and its treatment, and severe COVID-19: a population cohort study. The Lancet. Respiratory medicine. 2021.
Mogensen I et al. Lung function before and after COVID-19 in young adults: A population-based study. The journal of allergy and clinical immunology. Global. 2022.
Zhang H et al. 3-year outcomes of discharged survivors of COVID-19 following the SARS-CoV-2 omicron (B.1.1.529) wave in 2022 in China: a longitudinal cohort study. The Lancet. Respiratory medicine. 2024.
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