During the last few years, efforts to develop a preparedness plan for an avian flu pandemic have galvanized the world community. Though health experts worldwide may feel relatively well positioned to detect such an outbreak early, support international efforts to contain it in its earliest stages, and limit its spread, the reality is that its impact could be devastating. As the world shifts its focus away from other potentially catastrophic outbreaks such as severe acute respiratory syndrome (SARS), we cannot drop our guard against any pandemic.The real challenge in preparing for a pandemic outbreak involves putting in place a process by which the biopharmaceutical industry can respond quickly and effectively. The obstacles normally associated with vaccine production are exacerbated in a pandemic. If the industry is to ensure public safety, tasks such as indentifying the strain rapidly, compressing vaccine-development and process-development timelines, and translating global regulatory standards must be executed flawlessly. To meet the expectations of the global community, the industry must invest heavily in developing a well-defined business continuity plan that goes beyond normal business continuity and includes the task-compression activities required in response to a pandemic.
A History of Pandemics
The first of these changes in the virus, antigenic drift, is a minor modification in an antigen on the surface of a pathogenic micro-organism. This circumstance is typically the result of natural selection, in which the virus mixes with a partially immune population. Immunization against the original virus may provide some partial protection against the modified virus, but an epidemic could result if the situation is left unchecked.
The second of these alterations, antigenic shift, is a more lethal and abrupt change in antigenic composition. For example, the hemagglutinin (H) or neuraminidase (N) spikes from a human influenza virus could be replaced with a spike from a nonhuman animal, or an adaptive mutation could result in a major antigenic change. This type of change is called "re-assortment." In re-assortment, humans can become the "mixing bowl" in which a non-human virus strain, such as an avian strain, can mix or re-assort with a human influenza strain, resulting in a new strain that is immuno-logically unique, readily trans-missible, and consequently, much more effective as a human patho-gen. The 1918 Spanish flu virus began as an avian flu, and then it mixed with a human influenza virus to form the H1N1 influenza A virus subtype that attacked a quarter of the world's population.
Pandemic preparedness activity is currently focused on the H5N1 influenza A virus subtype, a bird-adapted strain, which is known as avian flu. To date, the H5N1 avian flu virus has been found in birds in 48 countries, and in pigs in China, felines in Thailand, and civets in Vietnam. When the first fatalities were recorded from the outbreak of avian flu, the US Centers for Disease Control and Prevention (CDC) estimated the fatality rate worldwide could range from 80 million to 100 million people if a pandemic outbreak were to occur. Since 2002, more than 385 cases and 243 deaths have been reported from the avian flu virus.2 Because of its ability to mutate and to be rapidly transmitted, the global community has focused on this virus.