Since the first COVID-19 case was reported in December last year, the viral infection spread across the globe, infecting more than 18 million people. At the earliest stage of the pandemic, the symptoms mostly indicated that the virus causes respiratory illnesses, but soon experts noticed several other symptoms such as delirium, diarrhoea, loss of taste and smell and even rashes on the skin in patients suffering from COVID-19.
This ability of the virus to cause secondary infections in the body has made it difficult for scientists treat COVID-19 with antivirals.
In a recent article published in the journal Photodiagnosis and Photodynamic Therapy, researchers from the Optics and Photonics Research Centre in Brazil suggested the use of photodynamic therapy as an additional treatment to fight these secondary infections in COVID-19 patients.
Secondary infections associated with COVID-19 infection
It is an established fact that SARS-CoV-2 is a respiratory virus, which primarily affects the respiratory tract and organs, including the lungs. However, most of the patients admitted to hospitals with COVID-19 infection have contracted bacterial co-infections as well. These bacterial infections could have been acquired either due to the attack of the virus on the organs or because of their presence in the hospital (nosocomial infections).
The most common secondary infection seen in COVID-19 patients was pneumococcal pneumonia caused by the bacteria, s treptococcus pneumoniae. Some patients also showed the presence of an infection caused by s taphylococcus aureus bacteria which can lead to flu-like symptoms, bone infections and skin infections.
Photodynamic therapy for treating COVID-19 related secondary infections
Photodynamic therapy does not directly kill the virus, but it uses light and a photosensitising chemical substance to kill microorganisms in the respiratory tract. The scientists found that photodynamic therapy generated reactive oxygen species and oxygen molecules which helped in damaging the targets of the virus.
The SARS-CoV-2 virus is able to enter the body mainly through the upper respiratory tract as there is natural colonisation of infection-causing microorganisms in the oropharynx (the area between the back of the mouth and the throat).
The scientists suggested that a specific pharyngotonsillitis photodynamic therapy can not only help in reducing the number of these microorganisms present in the oropharynx but also in preventing these microorganisms from penetrating the mucosa.
This therapy also activates the phagocytes (which ingest the harmful foreign organisms), thus preventing the multiplication of the microorganisms on the mucosa.
In order to prove their theory, the researchers conducted a photodynamic therapy test against bacterial pneumonia. In this test, the scientists used an extracorporeal illumination (light source) of wavelength 780 nanometres and used indocyanine green as a photosensitiser which was provided to the patients via nebulisers. The experiment concluded that no deaths were reported in the group who got the photodynamic therapy, while 60 percent of the control group participants died.
With this, the scientists concluded that photodynamic therapy can be used either as a single therapy or as an antibiotic adjuvant to treat secondary infections in COVID-19 patients. They further added that more clinical research is needed to be done to determine the dose and safety of the therapy.