COVID-19 disinfection myths debunked

The COVID-19 pandemic has generated many myths about the best way to get rid of the virus

COVID-19 disinfection myths debunked
Health workers disinfect the Tacuba General Hospital in Mexico City - Photo: Alfredo Estrella/AFP
English 29/07/2020 15:43 Mexico City Actualizada 17:04

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A man wearing a face shield and protective suit that seems to have come out of a low-budget movie about the moon landing sprays a liquid over the sidewalks at the San Pedro Mártir neighborhood while a car drives by a few meters away playing catchy music and a recording that announces Mexico City government’s commitment to health. This neighborhood, as well as others at the Tlalpan borough, is part of the hotspots linked to the warnings about the number of COVID-19 cases in a place where public activity was never limited and where, since the beginning of the pandemic, there were no effective campaigns that promoted the use of face masks, isolation, hygiene, and physical distancing. Upon being asked about his activity, the man says: “We’re sanitizing,” while he watches his co-worker trying to give hand sanitizer to the people in the street.

When the pandemic began, over half a year ago, there were pictures of squadrons cleaning Wuhan streets in China, although they became less striking when it was shown it was an inefficient measure. The World Health Organization (WHO)made it clear that the strategy was not useful for several reasons, for it is unlikely that the spray reaches all surfaces during the required contact time to deactivate the pathogen agents; moreover, the streets are not considered a reservoir of infection.

For Doctor Carlos Magis Rodríguez, an expert on Public Health from the UNAM’s School of Medicine, a problem when it comes to facing the pandemic are the mistaken ideas on how the virus can be cleaned up, for instance.

The answer is most probably not in these men “disinfecting” the streets with strategies similar to those used by fumigators who try to scare away cockroaches. “The virus is not there and the word ‘sanitize’ doesn’t even exist [in Spanish]. They are non-scientific responses to show, maybe, that something is being done, when, actually, insisting on frequent hand washing, staying at home, and wearing a mask are still the most effective [measures].”

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Sanitize is a verb in English whose most appropriate translation into Spanish is “to disinfect,” according to the National Royal Academy of Medicine. Thus in Spanish, the word “sanitizer” is an Anglicism that has been adopted since the pandemic with new connotations, such as aiming for deeper disinfection. For Doctor Alejandro Sánchez from the UNAM’s Biotechnology Institute, sanitization would be understood as reducing the number of pathogen agents to the minimum.

Dr. Alejandro Sánchez explains that bacteria and viruses have different responses. Bacteria are living organisms that respond in a specific way to cleaning agents and although many substances can kill them, this kind of microorganisms has strategies to become more resistant, such as becoming spores.

In the case of viral particles, we are not dealing with living organisms but with genetic material surrounded by fats and proteins. “A virus must be attacked to dissolve its fat and protein cover and thus free the genetic material that is highly degradable by itself. Soap molecules work like a spike that gets into this fat layer and breaks it.” SARS-CoV-2 is much easier to destroy than other organisms previously studied, but people do not follow the easiest health measures.”

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He explains that there are other agents that will also show these interactions. Their functions will also depend on the way they are applied. “Alcohol molecules have a part that can interact to dissolve a part of the virus’s cover. In cleaning, alcohol is used on 70% because it is harder for it to evaporate. Ethanol contained in a water solution in this percentage has the perfect balance to persist,” he says and adds that this substance is particularly effective for cleaning metal surfaces.

Other organic chemical compounds highly used in everyday cleaning products are the so-called quaternary amines contained in several disinfecting spray products. “They have a toxic effect which, although it is not big, will always depend on the level of exposure.”

With more people returning to public spaces, it is more common to see some objects that try to show people they are entering a disinfected area and thus stay calm. One of these objects are disinfectant mats that aim to sanitize shows with a disinfecting substance, such as diluted bleach. This kind of mat was first used over two decades ago in places linked to food production, such as farms. The Biotechnology Institute expert explains that they are commonly used in the agricultural or veterinary sector where there is a lot of contact with the ground due to the movement of animals.

“We must remember that the ground is not an area we can easily disinfect and, as a matter of fact, by touching a surface with the virus, I’m not going to get directly infected; the infection happens when you take your hands to your face, that is why keeping constant hygiene is enough to prevent contagions.”

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On the other hand, we must consider a product’s concentrations and the instructions regarding the time of disinfection, as well as cleaning before disinfecting because dust layers can protect the virus.

At the entrance of some shops, like restaurants, there are arches that have automatic sprinkler systems to spray the disinfecting solution on people inside them. The Health Ministry has said there is no evidence regarding the effectiveness of these systems to perform effective disinfection of SARS-CoV-2. It has also warned that the concentration of the disinfectant could not be enough to deactivate the virus and the spray could even ease its spread and thus be present in the clothes, hair, or accessories of people who under the arch, which increase the risk of spread.

The Health Ministry says that inhaling disinfecting substances can cause, among other things, injure to the respiratory tract, coughing, sneezing, and bronchial irritation, as well as unleashing asthma attacks, producing chemical pneumonitis and skin, eyes, and mucous irritation. Another problem with this kind of technology is that they could generate a false feeling of security in people who would consequently be less careful with basic prevention measures such as frequently washing their hands or practicing physical distancing.

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“There is no difference at a physical level, but there is one at a psychological level. This is an important variable to generate a bond of trust in a shop, but authorities’ observations must go beyond that. It would be to no use to “sanitize” clients when they arrive if no one in the kitchen wears a mask,” says Sánchez. He adds that the challenge after half a year of the pandemic seems to still be that people do not believe something as simple as water and soap can be the solution.

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