How Can Light Kill Viruses?

By: Jacob Silverman & Patrick J. Kiger  | 
A microscopic view of the COVID-19 coronavirus. Wilfried Pohnke/Pixabay

Key Takeaways

  • Light virus is a term used to describe viruses that don't cause significant symptoms or harm to their hosts.
  • These viruses often have minimal genetic material and may be beneficial by potentially protecting against more harmful viruses.
  • Understanding light viruses sheds light on the complex relationship between viruses and their hosts in the microbial world.

To stave off infection, there are some things you probably know you should do: wash your hands, be careful when you sneeze, gets lots of sleep, don't rub your eyes (especially after touching your nose), eat lots of fruits and vegetables. After all, a cold virus can survive on someone's hand for a couple of hours or for several days on some materials.

Even those hand sanitizers that many people use don't protect against everything. And once they're in the body, viruses are quite tough to kill — antibiotics are powerless against them and vaccines for influenza and some other viruses must be changed every year to adapt to new strains. Fortunately our immune systems can fight off many viruses, but others, like Ebola or the COVID-19 coronavirus, can be deadly.


For years scientists have been experimenting with technology for combating viruses with another method — by using a laser, a device which stimulates atoms and molecules to emit light and then amplifies it to create a beam of radiation.

Back in 2007, researchers at Arizona State University and Johns Hopkins University discovered that pulses of light from a laser could low-power laser could neutralize viruses — turning them into "rubble," as Wired magazine put it at the time.

In their study, the researchers blasted a virus with a quick pulse of purple laser light. The laser, which only shines for 100 femtoseconds (a femtosecond is one-millionth of a billionth of a second), causes the virus's capsid (its outer shell) to vibrate and become damaged. Essentially, the virus becomes "deactivated" while the area around the virus remains unharmed. The method didn't cause viruses to mutate either, which is a problem in other virus treatments and can lead to viral resistance.

Since then, research on use of lasers against viruses has continued. Eventually, it might be possible to use lasers to cleanse blood samples of viruses and other pathogens, making them safer to handle. Laser therapy might also be combined with blood dialysis treatments. In that approach, blood would be cycled out of a patient's body, lasers could eliminate any pathogens in the blood and the blood would be cycled back in. As this study, published in November 2019 by the National Institutes of Health, describes, it eventually might be possible to employ lasers to inactivate influenza viruses, so that they used to produce more effective vaccines.

On the next page, we'll look at more ways in which scientists try to fight viruses or stop their spread altogether. Several of them use light, whether to kill viruses or as an activating agent.


Other Ways to Combat Viruses

Streptococcus pyogenes bacteria, atop the surface of a human white blood cell. Public Health Image Library, Centers for Disease Control and Prevention (CCO)

While many efforts to stop viruses have yet to pass beyond laboratory trials, UV irradiation has already found its way into many real world applications. UV irradiation works by bombarding viruses with ultraviolet light, the same light that causes humans to develop sunburns and skin cancer.

Like the laser technique, UV irradiation kills viruses by breaking down their cell walls. Some ventilation and water-purification systems make use of UV irradiation to eliminate airborne or waterborne pathogens. Researchers have successfully used UV irradiation to kill foodborne pathogens, like E. coli bacteria, without diminishing taste or food quality. But while UV irradiation can be effective, it can also cause viruses to mutate and has the potential to damage healthy cells (as anyone who's suffered a sunburn can attest).


In March 2020, BBC News reported on the use of robots armed with bulbs that emit concentrated short-wavelength ultraviolet (UV-C) light to disinfect hospitals and reduce the chance of patients contracting infections there. There was hope that the technology would work against coronavirus, although there hadn't yet been testing to prove whether it would, according to BBC.

Researchers also have explored using microwaves to destroy viruses, but the technique has so far proved ineffective. The water surrounding viruses absorbs the energy from microwaves. The virus doesn't receive enough microwave energy to be affected, much less destroyed.

In July 2018, researchers at North Carolina State University published a paper in the journal ACS Publications, in which they described a new technique for adding light-sensitive molecules to plastics. When exposed to light, the molecules reportedly have the ability to poke holes in viruses and bacteria and render them harmless, according to an account of the research on the Alliance of Advanced BioMedical Engineering website.

For more information about viruses and related topics, please check out the links on the next page.


Frequently Asked Questions

Can light viruses have any negative impacts on their hosts?
While light viruses typically don't cause significant harm, there's potential for them to interact with other viruses or host immune systems in ways that could lead to negative outcomes, though research on this topic is ongoing.
Are there any practical applications or implications of studying light viruses for fields like medicine or biotechnology?
Studying light viruses may offer insights into viral-host interactions and could inform strategies for combating more harmful viruses, potentially leading to the development of novel therapeutics or vaccines.

Lots More Information

Related Articles

More Great Links

  • "UV Irradiation Dosage Table." American Air & Water.
  • Cook, John. "HaloSource of Bothell lands $15 million." Seattle P-I. July 27, 2007.
  • Dumé, Belle. "Visible light pulses knock out viruses in blood." NewScientist. July 27, 2007. (April 1, 2020)
  • Harris, Jaida. "Suntans are bad for bacteria too! Exposure to UV irradiation kills off harmful bacteria in food." Innovations Report. Dec. 15, 2003.
  • Khazeni, Nayer. "Chasing the Elusive Cold." San Francisco Chronicle. July 29, 2007.
  • Tibbetts, John. "Special Surface Coating Can Kill Most Bacteria and Viruses on Contact." Alliance of Advanced BioMedical Engineering. Nov. 18, 2018. (April 1, 2020)
  • Murray, Adrienne. "Coronavirus: Robots use light beams to zap hospital viruses. " BBC News. March 20, 2020. (April 1, 2020)