Covid-19: Detergent film may help with disinfection

Brazilian researchers have taken the first step in the development of a simple and cheap method to disinfect surfaces and hands. Laboratory tests have shown that a film of detergent can turn inactive the aviary coronavirus (a virus that causes flu in birds and that belongs to the same family of the SARS-CoV-2, the agent of Covid-19). Based on these good results, scientists will now evaluate the action of the formula against SARS-CoV-2 in the next phase of the study. If this effect is confirmed, the product may be used to disinfect surfaces and objects such as door knobs, handrails and trash cans, and as a hand sanitizer. The study was carried out by researcher of the Brazilian Agricultural Research Corporation (Embrapa), with the collaboration of the Oswaldo Cruz Institute (IOC/Fiocruz), of the Chemistry Institute of São Carlos of the University of São Paulo (IQSC/USP) and of the Institute of Zootechnics (IZ).

Two easy-to-prepare mixtures were evaluated in this work. The formula to disinfect surfaces was created using two parts detergent and one part water. The formula to sanitize hands uses 20 spoons of detergent and one spoon of soybean oil, added to increase plasticity and reduce skin drying. Both mixtures were spread on plastic slabs. After the products dried, forming a film, researchers incubated aviary coronavirus on the slabs for ten minutes. They then analyzed viral infectivity, that is the ability of a virus to cause infection. The test, which used embryonated chicken eggs, which are susceptible to the virus, confirmed that the pathogen was inactive on the slabs treated with the detergent film. As a comparison, the viruses remained active on the control untreated slabs.

A collaborator of the work, the researcher of the Compared and Environmental Virology Laboratory and director of IOC/Fiocruz, José Paulo Gagliardi Leite, explains that the tests made with the aviary coronavirus were a strategy to accelerate the research. Due to the risks to human health, experiments with the virus that causes Covid-19 must be made in laboratories with biosafety level 3 (NB3). “The aviary coronavirus is similar to the SARS-CoV-2, but it does not infect humans and can be manipulated in laboratories with lower safety levels. This is why it was chosen as a model. With these positive results, we have already started our preparations to test the detergent film against the SARS-CoV-2 at Fiocruz’s NB3 platform”, the virologist said.

The work also showed the long-term stability of the viral inactivation film. Tests have shown that the main components of the formula to disinfect surfaces have remained stable for up to seven days after application. The hand disinfecting lotion was not evaluated, as it was created to work during a few hours after application.

The first author of the paper, Embrapa researcher Luiz Alberto Colnago, points out that the long-term effect may be an additional advantage of the detergent film.

According to him, several disinfectants are capable of inactivating the SARS-CoV-2, but these products evaporate quickly, so that the surfaces can be contaminated again right after disinfection. “We believe that the antiviral activity of the film can be attributed, in great part, to the biocide action of surfactants, the main components of cleaning and personal hygiene products, present in the detergent. The chemical stability of the films indicates that the properties of the mixtures, including antiviral activity, wil be preserved for the same period of time, and may maintain a residual protecting effect”, he says.

According to the World Health Organization (WHO), COVID-19 is transmitted through droplets released through the mouth and nose of infected people, for instance, when they cough, sneeze, speak, or sing. Surfaces can be a source of dissemination of the disease, as people can get infected when they touch contaminated areas and then touch their eyes, nose or mouth. This is why it is advisable to wash one’s hands with soap and water or to use products containing alcool 70%. It is also a good idea to clean surfaces and objects, especially those that are touched often.

“Having cheap products available is very important for vulnerable populations in Latin America and Africa, some of the most vulnerable to the disease”, mentions Gagliardi Leite. “The results obtained in this study also point to the perspective of applying the film against other enveloped viruses”, he adds. In addition to its action against the SARS-CoV-2, researchers will also evaluate, in the next phases of the study, the efficacy of the detergent film agains other pathogens, the stability of the product on different surfaces, and its manual application.