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Global Pandemics

Between now and 2020 we are likely to see 2 to 3 major pandemics which will start in regions with low public health and rapidly spread globally and so demand fast response

Since the Spanish Flu pandemic of 1918 which killed over 50 million and infected 500 million, national governments have had an eye on the risks from widespread epidemics. With the advent of SARS a decade ago, the Avian flu pandemic in Asia in 2007 and the Swine flu pandemic that started in Mexico in 2009, the incidence and impacts of such events are causing more and more concern at international levels. The reasons for this are three fold: The speed at which pandemics can spread around the world has been significantly accelerated by increasing mass air travel; the consequential time available to track the source and initial progress is decreasing; and the capability to get the right drugs into the right place at the right time is not necessarily up to the challenge.

To understand the implications of future pandemics, we need to be clear on what is the difference between a pandemic, an epidemic and an outbreak: The CDC in the US defines an outbreak as simply the start infection in a localized geographic area. An epidemic occurs when a large geographic area is involved which has a higher than expected mortality rate than expected. A pandemic is a global outbreak that exceeds the “normal” levels of mortality and infection levels for typical disease. The key word here is “global”. There are two major factors which effect whether or not an outbreak will lead to a pandemic: Pathogenesis and virulence. Pathogenesis refers to how a virus will cause disease and how easily it is spread. The virulence refers to how sick a certain virus will make the host and how easily it can cause death.

The WHO maps out a pandemic based on six distinct phases: Phase 1 is when there is only non-human infections spreading and no animal-to-human transmission. In Phase 2 an animal influenza virus circulating among non-human animals which is known however to have caused infection in humans is identified, and is therefore considered a potential pandemic threat. Phase 3 sees animal-to-human transmission but no person-to-person transmission under normal living circumstances; when this is seem the risk of pandemic rises even higher. Phase 4 occurs when there is known human-to-human transmission of the virus. This allows outbreaks then epidemics to occur and even further increases risk of a pandemic. In Phase 5, human-to-human spread is documented in at least two countries in one WHO region and may well indicate that a pandemic is imminent. Phase 6, the pandemic phase, is characterized by outbreaks in at least one other country in a different WHO region in addition to the two or more countries defined in Phase 5. Designation of this phase indicates that a global pandemic is under way.

A core problem with pandemics is that they often arise in regions with low levels of public health and rapidly spread globally to more advanced countries. It is highly unusual for one to start in say the US or Europe. In tracing the cause of a pandemic, it is therefore vital to focus on ‘patient zero’ – the first personal to get ill. So, for example, the 2009 Swine flu pandemic started in Mexico and H1N1 patient zero in village of La Gloria, Veracruz next to large industrial pig farm. Notably this highlighted the rising risk from people and animals in many parts of the world increasingly sharing the same water sources. Although the 2009 pandemic was in many ways a false alarm as mortality rates were not excessive, it is seen in many circles as a good model for how global health authorities will need to cooperate in the future when more lethal strains of virus spread.

The swine flu pandemic also highlighted the problems in availability of suitable vaccines – both in terms of the right drugs and their global distribution. Although the re-emergence of influenza as a pandemic threat has stimulated the influenza vaccines market to be one of the fastest-growing sectors of the global pharmaceutical industry, many see that current vaccines will not help in the future. A critical issue here is the rate at which a virus variant can develop is faster than the speed at which new vaccines can be developed: Unlike many other diseases where a known condition already has an established therapy in place, pandemics are often new strains of virus and so need a new anti-viral vaccine. Typically creating this take around 6 months and so there is a significant gap between pandemic outbreak and treatment availability. Much hope is being placed on DNA based vaccines where DNA rather than dead virus particles grown in eggs is used as the base for developing new vaccines. These offer the potential for quicker responses and so enable faster global distribution.

In the next decade, many healthcare organisations expect that we will see two or three major pandemics that will have significant global impact. Given that Spanish flu killed around 3% of the world’s population at the time and infected around a third, the consequences of a similar event today are massive. If, for example, a new strain of Avian flu were to spread quickly from its source around the world, then some estimate that as many as 3 billion people could be infected within twelve months. If the right vaccines are not developed and distributed quickly, one in five of these could die within the year. As was highlighted in one workshop, “in many ways a global pandemic has to be seen as a greater threat to us than nuclear terrorism and global warming combined.”

There is therefore a significant global focus on ensuring global cooperation between health authorities and in improving monitoring of populations. The WHO has already taken a lead in the former area and, as shown with Swine flu, many of the processes are now in place and are being built upon: Potential global hot spots are continuously being identified to highlight emerging virus outbreaks and prevent future pandemics from reaching their full potential. Emerging infectious disease identification is seen as a major area for healthcare investment and one which is at the top of the investment in public health systems globally.

In terms of monitoring, several organisations see that this is where we will now see a significant increase in investment. Already several countries have advanced approaches in place. Most notably Singapore has developed a highly integrated system that ranges from detailed public information ( through to advanced surveillance. Singapore’s Quarantine System was developed during the SARS outbreak and people who had contact with infected persons were served with a Home Quarantine Order and placed on home quarantine for 5 or more days. Thermometers were issued to all citizens and daily reporting to a centralised system ensured that early rises in body temperatures were noted as an indication of likely infection so that quarantine could take place.

Moving forward, many countries expect to roll out more sophisticated systems for full population monitoring. Global bio-surveillance initiatives are in place to, for example, enable increased surveillance at border crossings and key transport hubs such as airports as these are they primary areas where cross infection can occur and spread. At a wider level, mass monitoring of vital signs is also underway in some countries where, for example, daily infra-red satellite images are cross referenced with location of mobile phones so that the individual body temperature of each member of a population can be monitored and, at the first sign of significant increase, just as in Singapore with SARS, they can be contacted and quarantined.

Global pandemics will happen in the next decade, the problem is that we don’t know from exactly where they will emerge and what form they will take. As such, the key challenges are in the fast and effective response to the initial outbreak and ensuring that epidemics do not become pandemics.

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