COVID-19 is far from the last pandemic on the planet

Publicação: 8 de October de 2020

Has our experience with COVID-19 already shown how to deal with future pandemics?

COVID-19 will not be the last pandemic that humanity will face, but there is still no way to know when and where the next one will come from, nor what will be the causative agent (virus, bacteria or other microorganism)

Scientists have been warning of a zoonotic pandemic for decades. And many warn that there will be more of them. But, after all, why are they inevitable?

Johns Hopkins University Center for Health Safety Professor Dr. Amesh Adalja, an expert in emerging infectious diseases, pandemic preparedness and biosecurity, explains that the world is full of microorganisms and it is a simple biological fact that infectious diseases will continue to impact us. “Some of these infections may spread widely due to travel times and patterns, to the rise of megacities and the interactions with animals – these forces favor the occurrence of pandemics”, he emphasizes.

Professor of the Department of Policy, Management and Health at the Faculty of Public Health of the University of São Paulo (FSP-USP), Dr. Fernando Aith, agrees and adds that pandemics are inevitable due to the fact that the world is interconnected. As the globe’s environmental relationship grows, so does the inter-relationship between people. “A virus from China arrives in Brazil in a short time, and thus new global health risks will spread with increasing speed and scope. If the risks are lethal, the situation is even worse”, he highlights.

Virologist at the Institute of Tropical Medicine of the University of São Paulo (IMT USP), Dr. Camila Malta Romano is categorical in saying that this is far from the last pandemic and says that it is just a matter of “when” and not “if” – another pandemic will happen. “Pandemics (global level), although less common than epidemics (local level) occur from time to time and we have past examples of sporadic situations like bubonic plague, more than one of influenza (Spanish, Asian, swine flu, etc.). However, it seems that lately the emergence of potentially pandemic agents has been more frequent. For example, influenza pandemics: 1918 – Spanish flu; 1958 – H2N2; 1968 – H3N2; 2009 – H1N1. SARS, caused by a virus very similar to the current SARS-COV-2, caused the first epidemic of the 21st century (2003) and even then, we knew it would not be the last. Therefore, the SARS-COV-2 pandemic will certainly not be the last”, she justifies.

Another relevant factor is that lately the emergence of potentially pandemic agents has been more frequent. Dr. Aith explains that this is because we are living in the Age of the Anthropocene, Planet Earth has ceased to be what it was before and started to have its environmental characteristics permanently altered by human action (atmosphere, soil, sea). This change implies, by virtue of nature, environmental adjustments for which we are not necessarily prepared, as has been increasingly frequent.

In the understanding of the veterinary doctor, researcher and professor at the Leônidas & Maria Deane Institute (ILMD / Fiocruz Amazônia), Dra. Alessandra Nava, what can be said is that the world will still face outbreaks of emerging zoonotic diseases. Some may have a pandemic potential, which would depend on the infectivity potential of the etiologic agent. “However, the emerging zoonotic outbreaks will be more frequent due to the systemic increase in the triggers for these emergences such as deforestation, forest fragmentation and conversion of forests to pasture, mining areas”, she points out.

Tropics most susceptible to an upcoming pandemic?

Some experts point out that South America, especially Brazil, and Central Africa are the regions most likely to produce the next epidemics. Dr. Romano recognizes that ecological, economic and population imbalances are triggers for the introduction of infectious agents in the human population, but there is no way to assume that the new pandemic will occur in underdeveloped countries.

Dr. Adalja believes that the Tropics are more susceptible to the next pandemic, since tropical areas have more human-animal interaction, more diverse animal species and frequent travelers. “This can lead to a relatively greater risk in these areas, but pandemics can arise anywhere (as H1N1 appeared in Mexico in 2009)”, he notes.

For Dr. Nava, high biodiversity, and high anthropic pressure are factors that increase the susceptibility of the Tropics, coupled with major changes in the landscape such as forest fragmentation and deforestation. She warns that what is happening in the Pantanal and the Amazon is very serious and these are situations that predispose to the emergence of emerging infectious zoonotic diseases.

The fact is that the recipe for a new health crisis is before our eyes: deforestation, destruction of habitats, expansion of intensive agricultural practices, animal husbandry, hunting and predatory exploitation of wildlife, which bring people closer to viruses and other pathogens new and old, allowing them to eventually jump to human hosts. Allied to this, disorderly urbanization, frantic mobility and international travel facilitate its dissemination. And we must not forget climate change, which also profoundly changes the behavior and dispersal of people, plants, animals and diseases themselves.

Prevent next pandemic

While the COVID-19 pandemic continues to leave a trail of millions of victims and trillions of losses in the economy around the world, there is an alert to the need to prevent another tragedy. Danger that grows with the environmental imbalance caused by human action itself. Dr. Aith recognizes that man himself creates risks, invading habitats and driving the world into an imbalance. “The action of the human being on the planet is altering the environmental balance in such a way that new risks to the life of Man on Earth will certainly come, whether from nature (viruses, earthquakes, climate change), or from human ingenuity (medicines, therapies, superbugs, cloning, Brumadinho), as well as the new social and work relationships that are being established (telework, social networks, etc.)”, he says.

Nevertheless, it is still possible to mitigate the effects and the number of deaths that an upcoming pandemic can cause. For Dr. Adalja, pandemic preparedness activities, such as surveillance, diagnostic tests, hospital preparedness and medical countermeasures are essential. “And the COVID-19 pandemic has taught us that it is crucial to act quickly and take the right measures in the beginning, before an outbreak gets out of hand. In addition, it is important to prevent policies, disinformation campaigns and attacks on specialists from interfering with the response”, he stresses.

Dr. Aith adds that it is essential to strengthen the health systems of States and create a more efficient system of global governance, giving more powers to the World Health Organization (WHO) to act in the control of future pandemics in a more forceful and resolute way, including intervening in states that do not comply with the Organization’s guidelines for combating the epidemic.

All are unanimous that in addition to avoiding it, the world must be better prepared to contain the next biological agent. Dr. Romano recalls that they talk about the scientific issue, they have the economic and political issues of each country. “Countries that best controlled the pandemic were those that took drastic action from the beginning and did not have to be many: closing borders and mass testing. Containing a pandemic is possible, but it is not a simple task. And it is our obligation to have learned something from this”, she stresses.

Also according to Dr. Romano, avoiding the next pandemic must be a global action. “As we already know that the chances of it also originating from animals and its close contact with humans, it is necessary to avoid deforestation, illegal trafficking of wild animals, the consumption of meat from these animals”, she adds. On the scientific side, it is necessary to study the microbial diversity present in animals (it is known that about 2/3 of all infectious diseases in humans were of zoonotic origin). The virologist also recalls that coronavirus, influenzas, arenavirus, paramixovirus (like Nipah, which has a pandemic potential) are there, infecting an immense diversity of animals, and with zoonotic potential. It is worth remembering that scientists, including Brazilians, have already identified more than 30 different coronaviruses in animals, which can virtually jump at some point to humans. The expert also draws attention to human cultural habits, such as the consumption of meat from exotic animals, but not only bats and monkeys: birds and any other animal can be virtually the source of the next pandemic agent.

For Dr. Nava, it is necessary to invest in actions with synergistic effects aimed at stopping environmental triggers for the emergence of these diseases and active monitoring. “In relation to environmental triggers: stop deforestation, curb the trafficking and hunting of wild animals and their commercialization and the markets that allow the coexistence and proximity of different animal and domestic species, situations that predispose to outbreaks of zoonotic infectious diseases”, she cites. Also according to the researcher, active monitoring involves the survey of pathogens that are circulating in the wild population and the continuous contact with the population neighboring the forest, in the places of greatest population growth and in the most preserved sites for understanding the dynamics that involve the different actors that are present in these interfaces.

Will the next pandemic be more or less deadly?

Dr. Romano says, it is difficult to predict whether it will be more or less deadly than the current one. And that this will depend on the characteristics of the biological agent present (virus, fungus or bacteria), lethality and transmissibility. The SARS pandemic in 2003, for example, spread rapidly and had a much higher mortality than COVID-19.

According to Dr. Aith, pandemics of the dimension of the current one do not occur very often. For him, the next one will be less deadly, but he considers that these phenomena should happen more frequently, until one appears deadlier than this at some future time.

In the opinion of Dr. Nava, what we know and learn from epidemics of zoonotic origin is that the disruption of the natural balance of the ecosystem that involves the competent hosts, vectors and reservoirs and the continuous contact with species that naturally would not be found, provides the appearances and adaptations of etiological agents to other hosts. “The reduction in biodiversity is a way of occurring this rupture due to the change in the transmission of pathogens and parasites. Similarly, what is supposed to have been the cause of the emergence of COVID-19”, she argues.

Finally, the researcher stresses that the standing forest offers us numerous ecosystem services, including the maintenance of the natural ecology of some diseases. The etiologic agent may be present in the wild population, however, it is diluted between its less competent hosts and its amplifying reservoirs, only reaching the human population when these natural cycles rupture. “Therefore, if we want to avoid new emergencies, we must stop deforestation, reforest, and curb global warming, where we will have emergence of vector diseases and origin in wild reservoirs, mainly rodents”, concludes Dr. Nava.

Learn more:

Q&A with Dr. Bernstein on the connections between COVID-19, climate change, and the environment

Solutions for preventing the next pandemic, a new article by Dr. Bernstein in Science

Opinion: Anticipating the Next Pandemic

Mandeep Dhaliwal: We need a green recovery to prevent the next pandemic

Preventing the next pandemic: How $30 billion can prevent the next COVID-19

As COVID-19 continues, experts warn of next pandemic likely to come from animals

The next virus pandemic is not far away