José Luis Jiménez Palacios, PhD in Engineering from MIT and professor in Chemistry and Environmental Sciences at the University of Colorado in the United States, is one of the world’s most renowned researchers in the field of aerosol study. He is part of the group of experts who wrote to the WHO about the importance of the airborne transmission of the coronavirus, an organization that at the beginning of the pandemic opted for measures related to the transmission of SARS-CoV-2 through surfaces. Now, he and his research colleagues have shown that the virus is transmitted mainly through the air, through aerosols: “To date, zero cases of COVID-19 contagion by surface have been demonstrated,” says the expert. . This type of spread would happen not only with this pathogen, but also with other respiratory viruses.
What are the main findings of your research on the transmission of COVID-19 and other similar respiratory viruses?
These respiratory viruses are present in saliva and respiratory fluid. They have to leave one infected person and reach the other. Either through the mucous membranes, through the nose, mouth and eyes or through the respiratory system, when inhaled. This can happen, in particular, in one of three ways. The first, through infected surfaces, also called by fomites, occurs for example when a person touches the hand of someone who has touched their nose, eye or mouth. Then, in two other ways: drops and sprays.
They are both small balls of saliva and respiratory fluids that come out of us. The aerosols can come out when you breathe, speak, sing, scream, cough, or sneeze. On the other hand, the drops are larger and tend to come out more when yelling, coughing or sneezing, on stronger exhalations. They differ in behavior by their size: the droplets are large, like a projectile that is visible, they fly through the air and infect if they hit you inside the eye, nose or mouth. But if they don’t hit anyone, they fall to the ground or surfaces.
What the WHO told us at the beginning of the pandemic was that it was the thick droplets and the surfaces that were contaminating. And that the spread by aerosols did not happen and was misinformation. Aerosols are smaller balls of saliva, which no longer behave like a projectile and fall to the ground, but are like tobacco smoke. It comes out floating in the breath, it follows the currents of the air, but then it slows down with the friction of it. Aerosols infect by breathing them, by inhalation, above all.
Why has this type of transmission been underestimated?
Because of a great historical prejudice. In 1910 there was a very important North American researcher, Charles Chapin, who said that airborne transmission was almost impossible, and that respiratory diseases were transmitted by droplets. This man was too successful and what he said became dogma, all the WHO experts were chapinistas.
It has cost us a lot because we were people from outside that field and they treated us as ignorant and did not listen to details or research. There has been a historical and sociological resistance, because those of us who said it were not from the insiders, from those who had the upper hand. And this has happened as a worldwide thing, in the WHO, in the US Center for Disease Control and Prevention (CDC) and in the health ministries of the entire world, practically. The evidence has accumulated, as of March of last year there was enough evidence, but there has been a year of resistance and they still do not say this clearly and do not recommend the measures that they would have to recommend. For example, they do not explain clearly about the masks, nor do they claim to wear masks of sufficient quality, nor do they clearly explain the transmission.
Aerosols are smaller balls of saliva, which no longer behave like a projectile and fall to the ground, but are like tobacco smoke. It comes out floating in the breath, follows the currents of the air
But once we have entered this pandemic, we have been talking for some time about the importance of transmission by aerosols. Why has it still been undervalued?
The WHO told us at the beginning that [la transmisión por] aerosols only happened in very special situations, in aerosol generation procedures hospitals. What has been seen with the research is that this is completely wrong, that the important thing is the transmission by aerosols, through the air. It is the main and, in my opinion, the only important form according to the current evidence, of transmission.
Should we forget about the other types, the surfaces and the drops?
Thick drops are only important if someone is coughing or sneezing into your face, and surfaces are not important, to date zero cases have been proven. If this were what is spreading the pandemic, it wouldn’t be that difficult to prove. It is possible that there is contagion of this type [por superficies], but it is not very likely and it is not what is spreading the pandemic. We have to focus on aerosols. The evidence we have is that it is the important one. Of course, you do not want anyone to cough in your face, distance is a good idea, but it is not what is spreading the pandemic. Regarding contagion by surfaces, there is a debate about whether it really does not happen at all or if little happens but it is difficult to detect. We must use the precautionary principle, assume that it is possible and continue to wash our hands, but disinfecting everything is a waste and contamination.
He is not a big fan of chemical disinfection, which was talked about so much in the first months.
The virus is made of proteins, lipids, and nucleic acids, just like we are. So what hurts the virus hurts us. These chemical compounds are transformed from pollutants in the indoor air, called volatile organic compounds, that come out of us, materials and cleaning products. Thus, they become more oxidized compounds and more toxic chemical aerosols. So things like ions, plasmas, photocatalysis, hydroxyls, ozone or sprays hypochlorous acid, chlorine dioxide, which are bleaches, alcohol and all this, it seems to me that it should not be used, and many of them seem outrageous.
We must use the precautionary principle, assume that it is possible [la propagación por superficies], and keep washing our hands, but disinfecting everything is a waste and contamination
What are the key measures to improve the pandemic situation?
Vaccines are very effective, at least with the variants we have now, but six months ago we did not know about the delta variant and now it is annoying us, because who knows in six months which variant we will be talking about and if there will be any that will be skip vaccinations. The key so that variants do not appear is to lower transmission, because variants appear when the virus reproduces within people, and some mutation is lucky and gives the virus advantages.
As now there are part of the people who are vaccinated and part who are not, the selection pressure is for variants to come out that skip the vaccines. As when many herbicides are used, weeds become resistant to these products, or bacteria to antibiotics. Nobody knows if it will happen, virologists are debating it a lot, but nobody is sure that it is not feasible. Transmission should then be reduced as soon as possible to reduce the health consequences for people who become infected and to reduce the possibility of mutations.
Do you think that these types of respiratory virus diseases and epidemics are specific or will they be more frequent in the coming years?
From what I have spoken to other scientists, viruses such as SARS or MERS have appeared in recent years. This is the fourth [epidemia] and it is the one that has been triggered because the others could be controlled. New viruses are appearing and passing from animals to humans, then this will continue to happen, and if humanity reacts as badly as this time we may have more pandemics.
Of course there are [enfermedades] Traditional flu is a mini winter pandemic to which we have become accustomed, here in the United States millions of people die each year, and yet it is much more preventable. COVID-19 measures have been seen to prevent the flu. Nor are we going to confine ourselves to winters, but we can selectively wear masks in elderly or at-risk people, in public transport or hospitals. This could greatly relax the transmission.
Governments could have given away good masks that filter and seal well, and have stopped the pandemic at a very low cost compared to other costs that have been incurred.
Since you mention masks, what is your opinion on how the matter has been handled? Are they as important as we have been told?
It is an effective measure, but it is not well explained or good masks are given. With the tremendous economic costs that governments have had with the pandemic, they could have given away good masks that filter and seal well, and have stopped the pandemic at a very low cost compared to other costs that have been had. But it is still undone and unexplained, it is still done in a confusing way. I also believe because some of those responsible still do not finish believing about the aerosols. They are still stuck with the drops, so any mask works for a projectile and they don’t quite understand it.
Has the mask come to stay, also after COVID-19?
It has come to stay like in China or Japan: it is not that they always wear it, but if they get on public transport in winter or are contaminated, they wear it. A selective use of the mask can be useful in certain situations and for people at higher risk. Before, people had a cold and went to work, now if there is no other option, they can put on a mask. There is a part of the population that will not want to wear the mask in any way, and another that will be more rational and will put it on in these situations.