The origins of COVID-19
As people across the world caught wind of the rapid spread of a novel and nameless virus, media outlets and social networks went into overdrive. A topic that was once the property of Hollywood became the focus of every news channel as disbelief gripped the globe. Ever since, we have been adjusting to life in ‘unforeseen and unprecedented circumstances’. However, despite the shocked rhetoric of politicians and newsreaders, the truth is that these unexpected times are really not so unexpected at all.
Was Covid-19 inevitable?
With the pain and loss that have characterised the pandemic, it is frustrating at best to think that any of this could have been anticipated. However, with a glance at the epidemiological data reflecting recent trends in the incidence and distribution of disease, a pandemic of this nature was distressingly easy to predict.
According to the World Health Organisation, 75% of the emerging infectious diseases identified in the last 30 years are zoonotic (1). This means that the pathogen causing the disease originated in animals and then came to infect humans in what is known as a ‘spillover event’.
Such diseases, termed ‘zoonoses’, have caused various high-profile outbreaks across the world in the last two decades. Zoonotic diseases include severe acute respiratory syndrome (SARS), avian influenza (bird flu), H1N1 virus (swine flu), Middle East respiratory syndrome (MERS), Ebola virus disease, and now, of course, Covid-19 (2).
Spillover events become more probable as humans come into increasing contact with animals. Urbanisation and the destruction of natural habitats are two of the major processes resulting in humans living in closer proximity to other species, but research on the origin of SARS-CoV-2 (the pathogen which causes Covid-19) suggests that the virus jumped from a live animal to humans in a wet market in Wuhan, China. It is believed that SARS-CoV-2 can be traced to a sarbecovirus reservoir in the horseshoe bat population, with a likely intermediary species, widely suggested to be the pangolin, enabling the transmission of the virus to humans (3).
Covid-19 therefore fits the trend suggested by epidemiological research and demonstrates that increasing contact with animals can indeed cause serious outbreaks of infectious diseases in humans. This is emphasised when we examine the likely source of Covid-19 in the exotic meat market, as an environment like this is a perfect storm for a spillover event considering the number of species kept alive in close proximity to one another and, crucially, to humans. Viewed epidemiologically, such an arrangement is a public health emergency waiting to happen.
Given the continued existence of such high-risk behaviours and environments in many parts of the world, and the growth of other human activities leading to increased human-animal contact, such as deforestation and mass animal agriculture, it was really just a matter of time for a zoonosis of this kind to spread extensively through the human population. For this reason, the value of a One Health approach is clearer than ever.
The Concept of One Health
One Health is an approach which requires an interdisciplinary effort to achieve improved public health outcomes. The basic principle underpinning the concept is the belief that human health is inextricably linked to that of animals and to the environment more widely, and that these areas must therefore be addressed in tandem.
In practice, One Health holistically approaches human health by considering and respecting other species and the environment; examples of relevant policies include stricter regulation of animal agriculture and welfare, efforts to address antibiotic resistance, sustainable forestry practices, and the careful monitoring and control of zoonoses such as Covid-19. Fundamentally, One Health proponents believe that human health cannot be viewed in isolation, and must be considered relative to our relationship with other living beings and the world around us.
With a One Health approach, we would not just be more aware of potential future pandemics, but capable of changing human behaviour to prevent them entirely. In the case of Covid-19, an effective One Health approach would have regulated the exotic meat market to mitigate the clear risks posed to human health, and the shortcomings here provide tough lessons for the future. Rather than preventing human to human transmission of a pathogen once the spillover event has already happened, One Health focuses on preventing the initial animal to human transmission, and thus stops the emergence of diseases with pandemic potential at the source.
Addressing the cause of Covid-19 may seem too little too late, but it is not needlessly retrospective. By confronting the facts explaining our current predicament and changing our behaviour accordingly, we will be able to prevent the next pandemic.