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Photodynamic therapy can fight infections due to COVID-19

Publicado em 02 julho 2020

Por Maria Fernanda Ziegler | Agência FAPESP

Photodynamic therapy can be an efficient ally in combating secondary infections caused by COVID-19. The use of the technique was advocated as a complementary treatment by researchers from the Optics and Photonics Research Center (CEPOF) in a letter published in the magazine Photodiagnosis and Photodynamic Therapy.

“COVID-19 brings complications that go beyond the virus and we must also be concerned with seeking treatments for these other problems. Treating these related infections can improve the prognosis of severe cases and, above all, of those patients who have been intubated and, therefore, are at greater risk of infection by other microorganisms, such as pneumonia-causing bacteria, ”he says. Vanderlei Bagnato, coordinator of CEPOF – a Research, Innovation and Dissemination Center at FAPESP, with headquarters at the University of São Paulo (USP) in São Carlos.

How does photodynamic therapy work?

Photodynamic therapy consists of eliminating microorganisms by oxidation using light and photosensitizing substances deposited in the patient’s respiratory tract. When interacting with light, the compounds used generate a type of reactive oxygen, called singlet oxygen, capable of oxidizing the membranes of viruses and bacteria, killing or inactivating these microorganisms.

“When the patient inhales these substances, it is possible to activate the drug with extracorporeal lighting, which begins to act on the microorganisms that are in the airways”, he says.

Despite the fact that photodynamic therapy does not act directly to fight the new coronavirus (SARS-CoV-2) – as it does not eliminate microorganisms present in the bloodstream, only in the airways -, the researchers emphasize the need to develop techniques to fight infections related to COVID-19 caused by bacteria and other viruses, avoiding intensive medical care and minimizing transmission to other people.

CEPOF has carried out several works on the use of the technique for the treatment of pneumonia, skin cancer and other diseases. “We are even going to start a study in pigs to evaluate the use of photodynamic therapy in cases of pneumonia. This stage precedes clinical tests on humans, ”says Bagnato.

The study must also be conducted by researchers from the University of Ontario, Canada, in partnership with the CEPOF group. “We hope that the study will be accelerated, not least because, although it is not yet known for certain, it is likely that people who survived COVID-19 may be more prone to respiratory complications, such as pneumonia, due to the consequences of severe inflammation. It is necessary to use new techniques, expand alternative treatments ”, he says.

In the letter, the researchers warn that, in the case of COVID-19, the spread of opportunistic pathogens occurs mainly in the respiratory tract due to the natural colonization of SARS-CoV-2 in the oropharynx. “Photodynamic therapy not only helps to reduce the number of microorganisms present in the oropharynx, but also prevents its penetration into the mucosa and, consequently, its proliferation”, they say.

The letter COVID-19: Beyond the virus. The use of photodynamic therapy for the treatment of infections in the respiratory tract (doi: 10.1016 / j.pdpdt.2020.101804), by Lucas D. Dias, Kate C. Blanco and Vanderlei S. Bagnato, can be read at

This text was originally published by FAPESP Agency according to the Creative Commons license CC-BY-NC-ND. Read the original here.