Associate Professor Yiyu Ou and Professor Paul Michael Petersen, DTU Fotonik. Foto: Thomas Sørensen.

UV light: A path away from antimicrobial resistance

mandag 28 feb 22
af Tobias Sydradal Lund


Yiyu Ou
DTU Electro
45 25 66 37


Paul Michael Petersen
Professor, Sektionsleder
DTU Electro
46 77 45 12

By using UV light, we can treat infectious diseases including COVID-19 without antimicrobials, a new review study from DTU indicates. The invited review article is adapted to the WHO’s COVID-19 research database.

Infectious diseases are one of the major burdens of the world’s healthcare system. Especially for low-income countries, where, according to the World Health Organization (WHO), six out of top ten causes of death are infectious diseases.

To prevent and treat infections, we often use antimicrobials: Medicines including antibiotics, antivirals, antifungals and antiparasitics. But as a response to the use of these medicines, the targeted pathogens (bacteria, viruses, fungi and parasites) change over time. Because of misuse and overuse of antimicrobials, some pathogens change so much, they become harder, sometimes impossible, to treat. This is called antimicrobial resistance, and the WHO declares it one of the top ten global public health threats facing humanity.

Society has an urgent need for new disinfection approaches that can inactivate pathogens effectively - without harming healthy cells and developing resistance. But, the WHO writes, the clinical pipeline of new antimicrobials is dry.

A new approach

Associate Professor Yiyu Ou and Professor Paul Michael Petersen from DTU Fotonik, has written an invited review article that explores and examines an unusual path towards a solution.  

The title of the article is ‘Application of ultraviolet light sources for in vivo disinfection’ and it is published in the Japanese Journal of Applied Physics. The remarkable thing about the article is that for the first time ever, first author Yiyu Ou and co-author DTU Professor Paul Michael Petersen have collected all available research on treating human infectious diseases with UV light.

Read the paper

"The UV light can activate the body’s defence system, which then kills the pathogen"
Yiyu Ou, Associate Professor at DTU Fotonik

“The UV light can activate the body’s defence system, which then kills the pathogen,” says Yiyu Ou.

The article has reviewed and analyzed the results of 59 peer reviewed papers. 

“Seeing all of these results together,” Yiyu Ou says, “it’s clear that this is a new way of taking on the global threat of antimicrobial resistance – without the risk of adding to the problem.” 

The ABC of UV light

Ultraviolet (UV) light can’t be seen by our human eyes, as it has a shorter wavelength than visible light. UV light is divided into three bands: UVA (315-400 nanometer nm), UVB (280-315 nm) and UVC (100-280 nm). 

UV light has been used for disinfection and sterilization since the 19th century when scientists discovered that sunlight can kill various kinds of pathogens. Especially UVC can kill 99.99 per cent of all infectious viruses and bacteria. Within seconds, the UVC light can kill the microbial intruder by destroying its DNA/RNA. 

UVA and most of the wavelength in UVB can’t make direct DNA/RNA damage to pathogens effectively. Instead, the two types of UV light can interact with the body’s own defense system and generate antimicrobial peptides or reactive oxygen species that can inactivate pathogens.

The illustration below shows how the different wavelengths of UV light penetrate the human skin and their corresponding microbial inactivation mechanisms.  

Penetration of UV irradiation into human skin. Copyright: Yiyu Ou and Paul Michael Petersen 2021 Jpn. J. Appl. Phys. 60 100501

Penetration of UV irradiation into human skin. Copyright: Yiyu Ou and Paul Michael Petersen 2021 Jpn. J. Appl. Phys. 60 100501

Treatment of COVID-19

Highly topical is the fight against the pandemic coronavirus.

“I see an enormous potential in using UV light for treatment of infectious diseases in humans – including coronavirus,” says Paul Michael Petersen, professor, group leader and Head of Section at DTU Fotonik.

Researchers from US has conducted a pilot study on COVID-19 patients. They showed that UVA irradiation can mitigate severe acute respiratory syndrome. This paper is just one of the studies concerning coronavirus that has been analyzed in the review study from DTU Fotonik.  

“I will say that it is very likely, that we can start using this technology on humans within just a few years,” says Paul Michael Petersen.

The WHO has adapted the review article to its COVID-19 research database, inviting researchers world wide to explore this new path of research alongside the DTU researchers.