Outbreaks of infectious diseases have long plagued humanity, and changed history. The Black Death ripped through Europe in the 14th century, killing a third of the population. Smallpox brought by European explorers radically transformed the fate of the Americas 400 years ago. And in just four months, Covid-19 has completely transformed life in the 21st century.
The mortal impact of infections is undeniably important. But even more dramatic are the victories humanity has won against them. These are less sensationalised, probably because they require sustained, steady effort.
The understanding of aseptic technique – in which health workers use procedures that prevent contamination during their work – began a long battle against surgical bacterial infections. The modern fruits of our success in this battle range from life-saving organ transplantation to cosmetic day surgery.
Vaccines have shattered rates of childhood mortality from bacterial and viral infections. They have also provided reproductive security, driving modern economic development by enabling couples to have fewer children while increasing their ability to attain an education and become more productive adults.
Even so, infectious diseases continue to be enormously significant. Not only can they disrupt cultures, countries and calm, but countering them is a necessary prerequisite to unleashing society’s innovative and productive capacity. It behoves us, then, to learn diligently from our experience with them.
Covid-19 is the most powerful infectious disease we have seen in the past 100 years. By “powerful” we do not refer to the speed with which it kills, but rather its integrated impact on society and the economy. Whole continents have been locked down. The energy of entire industries is being redirected to combat SARS-CoV-2, the strain of coronavirus that causes the disease. The scale of our response has been inspiring, and further testifies to Covid-19’s unique position in the compendium of infectious threats.
But it is important to remember that the world's sweeping mobilisation right now is again supported by sustained past investments in research and technology. In the next pandemic, we will have even more tools at our disposal, some generated during this period. Our response will be even swifter and more definitive, hopefully – but only if we learn from the current crisis.
There will certainly be a next outbreak, a next pandemic, and then others after that. We need to continue steady investment in research and technology. We also need full alignment within society, including politics and economics.
Several large-scale trends have contributed to Covid-19. These will make future outbreaks and pandemics more frequent and, possibly, more severe. One of them is growing urban populations, increasing both density and interactions. A second is greater global connectivity, both digital and physical.
Finally, urban development drives two further, complementary trends: encroachment on previously undeveloped areas, where animals, plants and microbes previously held dominion; and increased demand for and specialisation of food production, driving higher agricultural density and efficiency and the search for alternative foods.
There are doubtless other biological and non-biological factors that have contributed to Covid-19, but we focus on these as they highlight aspects of a formula that cannot be ignored: density + mobility + ecological disruption = outbreak risk.
Looking forward, then, what lessons can we learn?
Researchers and policymakers should look at pandemics as a negative externality from which we all suffer the consequences. Countries have utilised diverse strategies to tackle this pandemic. Even within individual countries like the US, different regions have responded in dramatically different ways, ranging from vigorously active measures to rather passive ones.
In the short term, we will learn which policies were most effective. In the longer run, we need to incorporate the strategies that worked best into preparations for future pandemics. We observe that, among the many policy debates occurring across the globe, economic imperatives are often placed in opposition to the advice of medical and scientific professionals. But more effectively incorporating disease outbreaks into our picture of negative externalities can help align economic and medical perspectives. Doing this would be useful in recruiting much-needed political support.
To cement the global learning curve and drive these policy innovations, it is necessary to take advantage of the coming "peacetime" when Covid-19 subsides and use it to bolster the World Health Organisation's ability to organise the global infrastructure for pandemic preparedness. Beyond that, we have to see climate change and the rise of "megacities" both as part of the problem and as part of the solution.
Emerging infectious diseases are a global problem, and we must act collectively as a planet. The next pandemic is just around the corner. We must learn from the past and the present to ensure our collective future. And we must do it quickly.
Yap Seng Chong is a professor in medicine and dean of the National University of Singapore Yong Loo Lin School of Medicine
Swaine Chen is an associate professor at NUS and group leader for infectious diseases at the Genome Institute of Singapore
