Copyright: Neil Moralee CC BY-NC-ND 2.0
China's coronavirus outbreak: what do we know, what can we learn?
Hitting the headlines daily is escalating concern about a new virus outbreak believed to have originated in the Chinese city of Wuhan. The virus is understood to be a new strain of coronavirus which is thought to have jumped the species barrier from animal to human. However, human-to-human transmission has been confirmed and Chinese health authorities have said there are over 17,000 confirmed cases in the country (as of 3 February) and 361 people have died.
Freya Jephcott is a highly experienced field epidemiologist and medical anthropologist, whose work focuses on improving our understanding of responses to outbreaks of unknown aetiology (causation / origin). The Cambridge Infectious Diseases Coordinator, Rachel Hoffmann, talks to Freya about the new coronavirus and more widely about the spread of infectious diseases:
Q. There’s clearly concern rising daily about the spread of the coronavirus and whether it will trigger a pandemic. The World Health Organisation has declared the virus as a public health emergency of international concern, with the current lack of information about how quickly the virus can spread, do you think we should we be worried?
This virus is still very new to us so there are a lot of questions that need answering before we can start making meaningful predictions about how significant this epidemic is likely to be. We know the virus can travel far via international flights, however, it’s still unclear how likely it is to spread once it reaches a new location and what the subsequent impact will be.
At present the most pressing questions relate to the timing and severity of symptoms and the point at which patients become infectious. These questions are important because they have bearing on our ability to effectively perform a containment strategy called “contact tracing”. This strategy involves identifying the people who have had contact or been in close proximity to a known case. If there is reason to believe that one of these contacts has become infected, then measures are usually put in place to prevent them spreading the virus further to more people. In fact, it was largely through contact tracing that public health professionals were able to curtail the 2002 SARS epidemic, which, appears to be the closest parallel we have to the current outbreak.
Obviously, if the window of time between people becoming infected and becoming infectious (known as the incubation period) is significantly shorter than it was with SARS, then we may struggle to identify and isolate cases fast enough to contain the outbreak. Similarly, if people are infectious before they are symptomatic, this would also impact our ability to quickly identify and isolate cases before the virus spreads to new people.
The relationship between the severity of the disease a virus causes and how quickly and how far it is likely to spread is more complicated. At present, it looks like the disease caused by this new and, as yet, unnamed corona virus may be milder than the disease that was caused by virus responsible for SARS. By that I mean that it seems that a smaller proportion of people infected with the virus go on to develop serious illness. Paradoxically, whilst this is a good thing on an individual level, it might make it harder to contain the epidemic. People with milder illness are less likely to seek help from formal healthcare facilities like hospitals and are generally less likely to come to the attention of public health authorities. This means that if these milder cases turn out to be infectious, they have the potential to spread the disease unnoticed, leading more people to become infected. This could in increase the total number of people who end up developing severe illness and possibly dying.
Regardless of what is revealed about the virus in the coming days, it is worth bearing in mind that the effectiveness of containment strategies will largely be determined by the nature of the population and the environment that it is entering into. Adequate food and housing, a well-resourced and trusted public health authority providing access to a robust health system, help to absorb an increased case load without becoming hotbed of infection itself. Conversely, for a malnourished population living in high-density housing, with an already high burden of infectious diseases and inadequate healthcare infrastructure, the consequences of an outbreak like this one are likely to be more extreme.
It is important to acknowledge, therefore, that when we talk about whether or not we ought to be worried about the current situation, that there is an enormous difference between the experiences of an outbreak somewhere like the UK, a well-resourced country with a relatively healthy population, as compared to a poorer country, where the consequences will be dire. In our responses to global pandemics, it is imperative that we acknowledge and attend to both populations, and both scenarios.
Q. Health authorities are saying that the virus originated from an animal host and was transmitted to humans by contact. Given the rapidly increasing human population and increasing global demand for animal protein, is this problem likely to get much worse?
It does appear that the frequency and the scale of disease outbreaks are increasing. This looks to be particularly true of zoonotic disease outbreaks, that is, those outbreaks that start when an agent like a virus makes the leap from an animal population into a human one, which is what we believe started the current outbreak in Wuhan.
The increase in zoonotic outbreaks is due to a range of factors, some of which influence the spread of infectious agents, such as viruses within animal populations, some affecting the likelihood of a virus making the leap to a human population (what we call a ‘spillover’ event) and some affecting the speed and ease with which the newly introduced virus then spreads amongst a human population.
A growing human population and an increasing demand for animal protein – and I should note here that high-density commercial animal farming as well as live wild animal markets are implicated in disease emergence – do constitute drivers of zoonotic outbreaks. However, they represent only a subset of the possible drivers in this case.
A number of environmental factors as well as behavioural ones are implicated here. From ecological disruptions and habitat loss, to the growth of high-density cities and increasingly mobile human populations, are all factors. Indeed, we do know that one of the risks with the current situation is that international flights can spread a virus further, faster than ever before.
There is no magic bullet to resolve this situation – at the point of an outbreak, it is in some ways already too late, as we have failed to mitigate the contributing factors further up the line. To tackle these issues in the future, we must reflect on our larger economic structures and think more critically about the way that we deal with global health, planetary as well as human, as we start looking at preventative rather than reactive responses.
Q. There is a lot of research being conducted in the underlying drivers of emerging diseases, to better target control programs and responses. How well do you think scientists are prepared for any future pandemic?
There is certainly a lot of excellent scientific research being done in this area at the moment. Responding to future global outbreaks, however, and more importantly, preventing these outbreaks in the first place, will depend on the efforts of more than just scientists. The complexity of drivers of outbreaks like this one means that a range of experts, including ecologists, economists, politicians, and anthropologists, all have a role to play in ensuring that society is organised in a way that is concomitant with maintaining global health. We need to bring their perspectives to the fore as we foster research across disciplines and encourage dialogue amongst a wider range of people.
Q. [and related to the above] Do you think that lessons have been learned from other infectious disease outbreaks such as Ebola, to help prevent other outbreaks from becoming an emergency?
Certainly, with each outbreak we advance our understanding and sometimes we also gain new, helpful technologies or protocols. However, we tend to forget the biggest lessons the fastest – whilst investment in tools and strategies for outbreak responses is crucial, without greater investment in prevention we are not going make much headway. With the increasing size and frequency of outbreaks we may in fact in find ourselves losing ground.
By prevention, I mean both addressing the drivers of disease emergence so that we see less outbreaks as well as investing in more stable, equitable and resilient societies, so when outbreaks do occur they are not as bad.
The current Ebola outbreak is a good example of this. Despite the development of an effective vaccine and targeted treatments, the outbreak is still resisting containment because it is occurring in a place of extreme poverty and instability. In short, we cannot rely on technological solutions, where basic public health infrastructure is absent. Our ability to implement interventions and mitigate the impact of deadly outbreaks will depend on the social, economic, and environmental conditions in our societies beforehand. These conditions cannot be meaningfully attended to once an outbreak has already begun.