Influenza Pandemic Preparedness 111

Table 1. Cumulative Number of Confirmed Human Cases of Avian Influenza A / (H5N1) Reported to the WHO up until January 25, 2006 (WHO 2005c) *

* WHO reports only laboratory-confirmed cases.

** Total number of cases includes number of deaths

Recent research suggests that the 1918 virus might not have been a reassortant virus (like those of the 1957 and 1968 pandemics), but more likely an entirely avian-type virus that adapted to humans (Taubenberger 2005). There is some evidence that the high pathogenicity of the 1918 virus was related to its emergence as a human-adapted avian influenza virus. The intriguing similarity in a number of changes in the polymerase proteins of both the 1918 strain and in the recently circulating, highly pathogenic strains of H5N1 avian viruses that have caused fatalities in humans (Taubenberger 2005), is reason for concern.

Considering that H5N1 is antigenically new, is highly pathogenic in humans and that it may acquire the ability to be efficiently transmitted from human to human, the World Health Organisation reiterated its 1997 call for all countries to prepare for the next pandemic, which it termed “inevitable and possibly imminent” (BWHO 2004), and updated its own pandemic preparedness plan in April 2005 (WHO 2005d).

Influenza Pandemic Preparedness

Planning is essential for reducing or slowing transmission of a pandemic influenza strain and for decreasing or at least spreading out the number of cases, hospitalisations and deaths over time. Preparedness will help to maintain essential services and to reduce the economic and social impact of a pandemic (WHO 2004).

Epidemiological models indicate that a pandemic would have the greatest impact on the poorest countries, as a result of limited surveillance and healthcare resources, as well as the general poor health and nutritional status of the population (WHO 2004).

Pandemic Phases

In order to define the sequence of actions during certain key events, the WHO Global Influenza Preparedness Plan (WHO 2005d) distinguishes different phases. Each phase is associated with international and national public health actions. The national actions to be taken during each phase are further subdivided according to the national epidemiological situation. The WHO strongly recommends that countries consider the national actions proposed in the WHO Global Influenza Preparedness Plan when developing or updating a national plan. A summary of these new phases is presented in Table 2. The world is presently (January 2006) in phase 3, as