Transportation and Pandemics

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Authors: Dr. Jean-Paul Rodrigue, Dr. Thomas Luke and Dr. Michael Osterholm

Dr. Luke: Department of Virology, Naval Medical Research Center. Dr. Osterholm: Director of the Center for Infectious Disease Research and Policy (CIDRAP), University of Minnesota.

1. Pandemics

There are approximately 1,500 microbes that are known to be a source of disease among the human population. Influenza can be one the most virulent among them because of its ability to mutate and be efficiently transmitted through the respiratory route. Under normal circumstances, influenza's impacts are relatively benign since populations have developed a level of immunity to its debilitating effects. Yet, it is estimated that between 1 to 1.5 million people per year die of influenza or related complications with a distinct seasonality that runs between October and March in the northern hemisphere and between May and September in the southern hemisphere. Influenza pandemics are thus considered to be among the most significant threats to the welfare of the global population.

Pandemic. An epidemic of infectious disease that spreads through human populations across a large area, even worldwide.

Over the last 300 years, ten major influenza pandemics have occurred. The 1918 pandemic (Spanish Flu) is considered to be yet the most severe. 30% of the world’s population became ill and between 50 and 100 million died. One important factor why the Spanish Flu spread so quickly and so extensively was through modern transportation, which at the beginning of the 20th century offered a global coverage. The virus was spread around the world by infected crews and passengers of ships and trains and severe epidemics occurred in shipyards and railway personnel.

Concerns about the emergence of a new pandemic are salient, particularly in light of recent outbreaks such as SARS (Severe Acute Respiratory Syndrome) in 2002-2003 and the Swine Flu in 2009, which quickly spread because of the convenience and ubiquity of global air travel. The next influenza pandemic could be equally severe and widespread illness or absenteeism in freight transportation sectors can cause cascading disruptions of social and economic systems. The relationships between transportation and pandemics involve two major sequential dimensions:

Transportation as a vector. With ubiquitous and fast transportation comes a quick and extensive diffusion of a communicable disease. From an epidemiological perspective, transportation can thus be considered as a vector, particularly for passenger transportation systems. The configuration of air transportation networks shapes the diffusion of pandemics. This issue concerns the early phases of a pandemic where transportation systems are likely to spread any outbreak at the global level.
Continuity of freight distribution. Once a pandemic takes place or immediately thereafter, the major concerns shift to freight distribution. Modern economic activities cannot be sustained without continuous deliveries of food, fuel, electricity and other resources. However, few events can be more disruptive than a pandemic as critical supply chains can essentially shut down. Disruptions in the continuity of distribution are potentially much more damaging than the pandemic itself.

2. Vectors and Velocities

The more efficient transportation, the more efficient is the vector that can transmit an infectious disease. International and long distance transport such as air and rail, modes and terminals alike, concentrates passengers and increase the risk of exposure. In the past, this could be an advantage as a ship could be quarantined, since there were ample time during the voyage for an infection to carry its course and the symptoms to become apparent. Today, it is a different matter as the velocity conferred by transportation systems for long distance travel is superior to incubation time of many flu variants (the period after the infection before symptoms are revealed). Since the incubation time for the average influenza virus is between 1 and 4 days, there is ample time for someone being infected to travel to the other side of the world before noticing symptoms. This represents the translocation phase and is the most crucial in a pandemic.

Once symptoms have developed, there is also a "denial phase" where an infected individual will continue traveling, particularly if going back to his place of origin. An infected individual beginning to show symptoms is likely to cancel an outbound travel, but will do the utmost, even breaking quarantine (or warnings), to go back home. Thus, in a window of a few days before an outbreak could become apparent to global health authorities, a virus could have easily been translocated in many different locations around the world. At this point, the vector and velocity of modern transport system would insure that an epidemic becomes a pandemic. In some cases, the velocity of global transportation systems is higher than at the regional level, which paradoxically implies that a virus can spread faster at the global level - between major gateways - than at the regional level.

Once an outbreak becomes apparent, the global passenger transportation system, such as air travel and passenger rail, can quickly be shut down in whole or in part, either voluntarily (more likely if the outbreak is judged to be serious) or by the unwillingness of passengers to be exposed to risks. The latter is what happened during the SARS outbreak in 2003. For instance, while the public transportation systems of several large Chinese cities were still operated, the number of users precipitously dropped because of risk avoidance. The SARS outbreak also had a substantial impact on the global airline industry. After the disease hit, flights in Pacific Asia decreased by 45% from the year before. During the outbreak, the number of flights between Hong Kong and the United States fell 69%. It is quite clear that this impact would be pale in comparison to that of a 12 to 36 month worldwide influenza pandemic.

3. Continuity of Freight Distribution

However dramatic the impacts of modern transportation as a high velocity vector for a pandemic, a potential greater risk resides in the geographical and functional structure of supply chains because the continuity of freight distribution could be compromised. Up to the mid-20th century, the scale of production, transport and retail was dominantly local (food) or regional (durable goods such as cars). Since then, globalization expanded substantially the scale at which a wide array of goods is distributed. Thus, the interconnectedness of the global economy, while being a net advantage from a supply chain standpoint, could make the next influenza pandemic more devastating than the ones before it. Even the slightest disruption in the availability of parts, finished goods, workers, electricity, water, and petroleum could bring many aspects of contemporary life to a halt. The global economy has been favored by the exploitation of comparative advantages and a more tight management of supply chains. Inventories are kept to a minimum. Virtually no production surge capacity exists. As a consequence, most markets depend on the timely delivery of many critical products (such as pharmaceuticals, medical supplies, food, and equipment parts) and services (such as communications support).

The transportation industry has also consolidated into a small number of global and national mega-players to achieve massive economies of scale. This is the case for the two most important global freight transportation modes; maritime shipping and air cargo. Since the frequency, speed and reliability of shipments are high under normal circumstances, manufacturers have relocated their facilities to lower cost locations. Because transportation costs are lower than inventory management costs, retailers and secondary manufacturers employ “just-in-time” inventory systems - their “stockpile” is flowing in the transportation stream as inventory in transit. Most supply chains are re-stocked on a continuous basis, on par with the demand, which is labeled pull logistics. The typical efficiency, and potential non-resiliency, of critical supply chains as a function of transportation would be placed under stress during a pandemic. The most important include:

Food. Modern food production and distribution relies on low levels of inventory, particularly to avoid wastes of perishable products on store shelves. On average, supermarkets have between 2 to 5 days of inventory of perishable goods (dairy, produce, meat) and about 1 to 2 weeks for other goods (pasta, canned goods, etc.). It is worth underlining that these figures are for a normal and stable demand. In the case of a pandemic, available food supplies could quickly be exhausted through hoarding behavior. Food security is therefore defined by the ability of the transportation workers to move food from producers, to the bulk-storage facilities, to the processor and lastly to the grocer.
Energy. The provision and distribution of energy is critical to the functioning of a modern economy and society. For instance, about 40% of the world's supply of electricity is generated by burning coal (50% for the United States). Coal power plants maintain a fairly low stockpile, about 30 days, and rely on a constant supply from major coal mining regions, which tend to be far away. While a pandemic would not directly damage energy systems, many energy distribution systems could be threatened through the removal of essential personnel from the workplace for weeks or months and impaired transportation capabilities to supply power plants.
Medical supplies. A pandemic is obviously associated with a surge in the use of medical facilities, equipment and pharmaceutical products. Global drug production is controlled by a few large conglomerates that maintain a limited number of facilities at selected locations. Commonly, a single drug is produced at a single plant. If global distribution systems were impaired during a pandemic, many essential drugs would have difficulties to reach patients while limited stockpiles maintained at medical facilities would quickly run out. For instance, over 95% of all generic drugs used in the United States are made offshore, primarily in China and India. A similar pattern applies to critical medical equipment such as ventilators. Even simple respiratory masks could quickly run out. All these shortages are likely to result in additional deaths.

It is very likely that a pandemic would quickly exhaust available food, energy and medical resources, replacements will not be forthcoming. Thus, supply chain issues are expected to seriously compound the impacts of an influenza pandemic.

4. Possible Mitigation Strategies

Many pandemic preparation plans fail to account the full importance and ramifications of global supply chains. They are essentially designed with the assumption that national economies, namely the United States, are mostly self reliant. The geographic and functional realities of the global economy are quite different from this assumption. Cascading disruptions in vulnerable freight transportation systems and strategic supply chains can compound the difficulties of maintaining social cohesion and critical infrastructures during a pandemic. Transportation workers must therefore receive a high priority for support – including vaccine, prophylactic antivirals, public health interventions and access to health care. Pandemic planners must cooperatively develop plans and obtain the agreements and resources necessary to conduct health assurance campaigns at major transportation chokepoints and corridors.

The basic strategy to protect the transportation system is to provide the workers with vaccine, prophylactic medications, protective equipment and physical security under the umbrella of transmission shielding operations as they move from and into transportation chokepoints and at suitable points along major corridors (i.e. weigh stations, etc.). Transportation workers must also have a well-enunciated priority for healthcare services if they become ill during their work travels. This will require that some national, state and local pandemic resources and response activities are reprioritized from traditional influenza priority groups (elderly, etc.) to insure that all citizens have a reliably adequate supply of essential supplies and services. Using modern communication systems, national, state and local licensing and regulatory authorities, industry and unions can identify, locate, educate and train the transportation workforce. Governments and transportation stakeholders (industry, unions, and workers) must create a cooperative plan that identifies roles, resources and responsibilities.

Because transportation workers must cross international and local borders, national and local entities, industry and unions, health agencies and other stakeholders must provide this support without regard to their nationality or state of origin. The international maritime domain presents unique challenges as it plays a fundamental role in supporting the global distribution of essential commodities (food and energy), parts and finished goods. The naval services of nations should prepare to establish task forces in international waters to quickly provide vaccine/antivirals and other health assistance to the multinational mariners of commercial vessels as they transit into or out of maritime chokepoints and sea lanes. International entities such as the North Atlantic Treaty Organization, the International Maritime Organization, or the Global Maritime Partnership initiative, can provide the organizational framework to protect global maritime commerce.