Ongoing Trials of Low Dose Radiation Therapy for Covid-19 Pneumonia: Studying the Past to Define the Future?

The current COVID-19 pandemic, caused by the infection by the SARS-CoV-2 virus, is a disease with great contagiousness, a non-negligible morbidity rate and a very important consumption of health resources, which is leading to a blockade of practically the entire world health system. The main complication is pneumonia, which has an important inflammatory component and for which there is still no definitive treatment. The absence of a standardized treatment coupled with the possible failure in the supply of drugs due to the great existing demand makes it necessary to investigate new anti-inflammatory therapeutics. The anti-inflammatory efficacy of Low-Dose Radio Therapy (LD-RT) has been confirmed in several experimental models, both in vitro and in vivo, as well as in different clinical studies. The radiobiological mechanisms that confirm this claim are becoming increasingly well known. Unlike high-dose radiotherapy that induces the production of pro-inflammatory cytokines in immune and endothelial cells, low doses of radiotherapy (0.5-1.5 Gy) act on the cells that participate in the inflammatory response, producing anti-inflammatory effects. At this time, there are different clinical studies underway that seek to demonstrate the usefulness of LD-RT against COVID19 pneumonia and open the possibility of offering an effective and widely affordable therapeutic alternative for this infection. Perhaps, as Confucius wrote, it is necessary to “study the past if you would define the future”