New Findings: How the Coronavirus damages the lung

Under the leadership of BREATH scientist Prof. Dr. Danny Jonigk, an international research team has studied the effects of the Coronavirus on lung tissue. The results of the comparison of lungs from persons who died from COVID-19 and lungs from those who died from influenza have recently been published in the renowned New England Journal of Medicine.

An infection with the Coronavirus can, like severe flu, seriously damage the lungs and lead to fatal respiratory failure. Exactly which molecular changes SARS-CoV-2 triggers in the pulmonary tissue of male and female patients and how these differ from the damage caused by the influenza virus is, however, hardly known up to now. In order to better understand the processes of the disease, an international research team from Germany, USA, Belgium and Switzerland, led by Prof. Dr. Danny Jonigk, a lung specialist at the Institute of Pathology at Hannover Medical School (MHH), has examined lungs from patients who died from COVID-19 and compared these with lungs from patients who died from influenza. „The study advances our knowledge as to why the lung function of those infected with SARS-CoV-2 with severe disease progression is so greatly affected“, emphasizes Prof. Jonigk, who is a member of the German Center for Lung Research (DZL). The results of the study entitled „Pulmonary Vascular Endothelialitis, Thrombosis and Angiogenesis in COVID-19“ have now been published in the renowned „New England Journal of Medicine“.

Microthrombi clog the finest veins

„First, we examined the tissue samples synergistically with a very wide spectrum of methods from micro-computed tomography, 3D electron microscopy and various molecular biological methods to detect the paths of SARS-CoV-2“, explains Prof. Jonigk. In this way, the scientists were first able to detect the already known acute damage pattern in the lungs of COVID-19 patients, the so-called diffuse alveolar damage. This occurs when the walls of the pulmonary alveoli become inflamed and extensively covered with protein deposits, thus hampering the oxygen supply to the blood. „We have also found a massive number of blood clots in all sections of the blood vessels in the lung, but especially in the finest veins, the capillaries“, says the pathologist. „These microthrombi clog the fine pulmonary vessels, thus also increasing the respiratory distress in the patients.“ This phenomenon also occurs in seriously damaged lungs after influenza infections, but the number of these small blockages found in influenza deaths is significantly lower.
One further finding is particularly noticeable, which medical practitioners otherwise know mostly only from tumor diseases, autoimmune diseases or scarring processes: SARS-CoV-2 apparently triggers a particular form of vascular regeneration in the lung. Prof. Jonigk stresses that „This so-called intussusceptive neoangiogenesis has not yet been described in connection with diffuse alveolar damage and thus differentiates COVID-19 fundamentally from comparably severe lung infections due to influenza viruses“, and he summarizes:
„The three changes occurring in the lung due to SARS-CoV-2 infections, as comprehensively described for the first time in our study, are the massive blood vessel damage, the excessive blood clotting, clogging the finest lung pulmonary vessels, and the angiogenesis characteristic of COVID-19.“
The pathologist considers the study results to be a further piece of the puzzle to decipher COVID-19. Although the enigma of the Coronavirus is far from being solved. Further studies are essential to understand the mechanisms of the vascular changes and ultimately translate these into therapeutic approaches.

• The original publication is available online on the New England Journal of Medicine site
• Further information is available from Prof. Dr. Danny Jonigk: by telephone +49 511 532-9532, by Email and under


Text: MHH

Photo: MHH/ Tom Figiel

The team of the working group lung research in Hanover

Prof. Dr. Danny Jonigk, Leader of the working group lung research