20 Years of Viral Threats
6th December 2022 - Last modified 18th October 2023
20 years of Alto. 20 years of science. #17
By Bree Foster PhD, Science Writer
As part of Alto Marketing’s 20 year celebrations, we’re looking back at some of the most important advances in science over this time in our blog series “20 years of Alto. 20 years of science.” Today, we’re talking viruses, specifically pandemics. Although COVID-19 is frequently referred to as a “once in a lifetime” or “once in a century” pandemic, it wasn’t the only one to occur in the past 20 years. In fact, it was one of many. Find out more about the pandemics of the last 20 years, why this may be happening more often, and how our governments and agencies are planning to prevent the next pandemic.
It’s hard to look back over the last 20 years and not think about the last two in particular – when a back-packing virus stopped the world, keeping us in our homes and fundamentally changing how we work and live. Many of us are still affected and struggle to reclaim the normality of busy crowds and no longer having two metres of personal space!
However, viruses aren’t a new concept and neither are the pandemics that they can cause. While COVID-19 has emerged as one of the most fatal disease outbreaks known to mankind [1], it was only one of many pandemics that we have encountered in the last 20 years.
And it won’t be the last.
What is a pandemic?
The terms “endemic,” “outbreak,” “epidemic,” and “pandemic” describe how frequently a disease occurs in contrast to its expected rate and how widely it spreads geographically [2]:
-Endemic: A disease that is well-established in a population and spreads at a predictable rate i.e., a common cold.
-Outbreak: This is characterised by an unanticipated increase in the occurrence of a disease or the emergence of cases in a new area.
-Epidemic: An outbreak that spreads to a wider geographic area.
-Pandemic: An epidemic that spreads to and occurs in multiple countries or continents.
Prior to 1900, infectious diseases were the leading cause of death worldwide, particularly pneumonia, the flu, and tuberculosis (TB) [3]. However, the successful implementation of public health initiatives, the introduction of vaccines, and the development of antimicrobial compounds greatly diminished the mortality rate from infectious diseases.
When the World Health Organization (WHO) declared that smallpox had been eradicated in 1980, there was a great deal of optimism that infectious disease would soon be a thing of the past [4]. However, viral outbreaks have continued throughout the past 20 years, and the rate at which they occur is increasing, possibly due to increased globalisation, air travel, and population growth [5].
An increase in global population has led to the growth and intensification of agriculture, increasing the likelihood of human contact with wildlife and the emergence or evolution of dangerous livestock pathogens. Recent decades have seen repeated pathogen emergence from wild or domestic animal reservoirs into human populations, from Bird flu to the Middle East respiratory syndrome coronavirus (MERS-CoV) to COVID-19 (Table 1).
What are zoonotic diseases?
In the past three decades, more than 30 novel human pathogens have been discovered, 75% of which are zoonotic [6]. Zoonoses are illnesses and infections that naturally spread from animals to humans. This includes both infections spread via direct contact with animals and indirectly through vectors like mosquitoes, the environment such as chicken coops, and through the consumption of infected food. Zoonoses are estimated to cause millions of fatalities and billions of cases of disease each year [7]. Due to the nature of zoonotic diseases, new pathogens can emerge and spread across countries at unpredictable rates. These infections tend to have a high rate of fatality, and there often isn’t a readily available treatment or vaccine to stop the spread of disease. As a result, zoonoses create high burden on health systems and cause significant economic losses to affected countries through the loss of animal trade, travel and – in the case of COVID-19 – a significant loss of human life and the shutdown of whole economies.
Table 1. Viral pandemics over the last 20 years.
| Year(s) | Virus | Geographic Location | Cases/Mortality | Zoonotic? |
| 2002-2003 | Severe acute respiratory syndrome coronavirus (SARS-CoV) | Originated in China, spread to 32 countries | 8,422 cases and 919 deaths [8] | Yes, it’s believed to have been transmitted from bats to humans via a civet |
| 2006 | H5N1; Bird Flu | Affected 9 countries in southeast and east Asia | 115 cases, 79 deaths [9] | Yes, from birds |
| 2009 | H1N1; Swine Flu | Worldwide | 284,000 deaths [10] | Yes, from pigs |
| 2014-2016 | Ebola | Mainly West Africa, primarily Guinea, Liberia, and Sierra Leone | 28,600 cases and 11,325 deaths reported [11,12] (likely underestimates) | Yes, likely transmitted from a bat |
| 2012-ongoing | Middle East respiratory syndrome coronavirus (MERS‐CoV) | Cases have been reported to WHO from 27 countries | Between April 2012 and December 2019, there have been 2499 laboratory-confirmed cases and 858 deaths [13] | Yes, transmitted via camels. |
| 2016 – ongoing | Dengue | Worldwide | Approximately 4.5 million cases and 1000 deaths in 2016 [14] | Yes, transmitted by mosquitos |
| 2019-ongoing | COVID-19 or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) | Worldwide | 633 million cases and 6.5 million deaths [15] | Yes, likely emerged from an animal in Wuhan, China |
How to prevent the occurrence and spread of emerging zoonotic diseases
The complex processes that lead to the emergence or re-emergence of zoonotic diseases are influenced by many variables, including genetic evolution, demographic changes, the availability and quality of healthcare resources, environmental conditions, and climate change. This means that any attempts to prevent the occurrence and spread of zoonotic diseases need to be multidisciplinary and recognise the interdependence of human, animal and environmental health.
The One Health approach [16] aims to achieve better public health outcomes by increasing collaboration across sectors responsible for public health, environment, agriculture and animal health. Implementing a One Health focus across sectors such as laboratory work, surveillance, planning and response, can further the understanding, prevention and early detection of potential threats that originate at the interface between humans, animals, and their environments.
The Future of Viral Threats
With rapidly changing ecology, urbanisation, climate change, increased travel and fragile public health systems, pandemics will become more frequent, more complex and harder to prevent and contain. As the Executive Director of the Health Emergencies Program at the WHO has said [17]: “We are entering a very new phase of high-impact epidemics… This is a new normal, I don’t expect the frequency of these events to reduce.”
However, not all hope is lost. Healthcare continues to improve globally with greater access to care such as therapeutics, improved sanitation and the development of vaccines. Additionally, advancements in genetic research and technology have allowed for quicker diagnosis, analysis and treatment for viral threats. In fact, Chinese scientists were able to sequence the entire genome of SARS-CoV-2 within a week of the virus’s identification [18]. This was followed with international tracking, the development of accurate diagnostic tests and the quickest vaccine production in history.
This accelerated vaccine development was partly made possible thanks to the arrival of mRNA vaccines to the scene. This type of vaccine is much more straightforward to produce than traditional vaccines and holds significant promise for treating diseases in the future. Future efforts to develop universal vaccines and increased cooperation through a One Health strategy should represent a significant advancement in the fight against current and emerging infections.
While the future holds many challenges, we have shown time and again that we can meet them.
References
(1) Bhadoria, P., Gupta, G. and Agarwal, A. (2021) ‘Viral Pandemics in the Past Two Decades: An Overview’, Journal of Family Medicine and Primary Care, 10(8), pp. 2745–2750. Available at: https://doi.org/10.4103/jfmpc.jfmpc_2071_20.
(2) Grennan, D. (2019) ‘What Is a Pandemic?’, JAMA, 321(9), p. 910. Available at: https://doi.org/10.1001/jama.2019.0700.
(3) Shaw‐Taylor, L. (2020) ‘An introduction to the history of infectious diseases, epidemics and the early phases of the long‐run decline in mortality’, The Economic History Review, 73(3), pp. E1–E19. Available at: https://doi.org/10.1111/ehr.13019.
(4) Strassburg, M.A. (1982) ‘The global eradication of smallpox’, American Journal of Infection Control, 10(2), pp. 53–59. Available at: https://doi.org/10.1016/0196-6553(82)90003-7.
(5) Baker, R.E. et al. (2022) ‘Infectious disease in an era of global change’, Nature Reviews Microbiology, 20(4), pp. 193–205. Available at: https://doi.org/10.1038/s41579-021-00639-z.
(6) Jones, K.E. et al. (2008) ‘Global trends in emerging infectious diseases’, Nature, 451(7181), pp. 990–993. Available at: https://doi.org/10.1038/nature06536.
(7) Gebreyes, W.A. et al. (2014) ‘The Global One Health Paradigm: Challenges and Opportunities for Tackling Infectious Diseases at the Human, Animal, and Environment Interface in Low-Resource Settings’, PLoS Neglected Tropical Diseases, 8(11), p. e3257. Available at: https://doi.org/10.1371/journal.pntd.0003257.
(8) Yang, Y. et al. (2020) ‘The deadly coronaviruses: The 2003 SARS pandemic and the 2020 novel coronavirus epidemic in China’, Journal of Autoimmunity, 109, p. 102434. Available at: https://doi.org/10.1016/j.jaut.2020.102434.
(9) Cumulative number of confirmed human cases for avian influenza A(H5N1) reported to WHO, 2003-2022, 27 June 2022. Available at: https://www.who.int/publications/m/item/cumulative-number-of-confirmed-human-cases-for-avian-influenza-a(h5n1)-reported-to-who-2003-2022-27-june-2022 (Accessed: 17 November 2022).
(10) Dawood, F.S. et al. (2012) ‘Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: a modelling study’, The Lancet Infectious Diseases, 12(9), pp. 687–695. Available at: https://doi.org/10.1016/S1473-3099(12)70121-4.
(11) Bell, B.P. (2016) ‘Overview, Control Strategies, and Lessons Learned in the CDC Response to the 2014–2016 Ebola Epidemic’, MMWR Supplements, 65. Available at: https://doi.org/10.15585/mmwr.su6503a2.
(12) History of Ebola Virus Disease (EVD) Outbreaks | History | Ebola (Ebola Virus Disease) | CDC (2022). Available at: https://www.cdc.gov/vhf/ebola/history/chronology.html (Accessed: 17 November 2022).
(13) Memish, Z.A. et al. (2020) ‘Middle East respiratory syndrome’, Lancet (London, England), 395(10229), pp. 1063–1077. Available at: https://doi.org/10.1016/S0140-6736(19)33221-0.
(14) WHO | Dengue and severe dengue. World Health Organization. Available at: http://www.who.int/mediacentre/factsheets/fs117/en/ (Accessed: 17 November 2022).
(15) WHO Coronavirus (COVID-19) Dashboard. Available at: https://covid19.who.int (Accessed: 17 November 2022).
(16) One Health. Available at: https://www.who.int/europe/initiatives/one-health (Accessed: 6 December 2022).
(17) BBC News (2019) ‘Large Ebola outbreaks new normal, says WHO’, 7 June. Available at: https://www.bbc.com/news/health-48547983 (Accessed: 18 November 2022).
(18) Chinese researchers reveal draft genome of virus implicated in Wuhan pneumonia outbreak. Available at: https://www.science.org/content/article/chinese-researchers-reveal-draft-genome-virus-implicated-wuhan-pneumonia-outbreak (Accessed: 21 November 2022).
