Influenza Pandemic: Efforts Under Way to Address Constraints on Using Antivirals and Vaccines to Forestall a Pandemic

摘要

Pandemic influenza poses a threat to public health at a time when the United Nations' World Health Organization (WHO) has said that infectious diseases are spreading faster than at any time in history. The last major influenza pandemic occurred from 1918 to 1919. Estimates of deaths worldwide if a similar pandemic were to occur have ranged between 30 million and 384 million people. Individual countries and international organizations have developed and begun to implement a strategy for forestalling (that is, containing, delaying, or minimizing the impact of) the onset of a pandemic. Antivirals and vaccines may help forestall a pandemic. GAO was asked to examine (1) constraints upon the use of antivirals and vaccines to forestall a pandemic and (2) efforts under way to overcome these constraints. GAO reviewed documents and consulted with officials of the Departments of State and Health and Human Services (HHS), international organizations, and pharmaceutical manufacturers. WHO commented that the report was comprehensive and useful. HHS stressed that vaccines and antivirals must be viewed in a larger context. State and HHS commented that the term 'forestall' is ambiguous and misleading. However, GAO has used the word in a way that is consistent with WHO's use of the term. The use of antivirals and vaccines, two elements of the international strategy to forestall a pandemic, could be constrained by their uncertain effectiveness and limited availability. To use antivirals effectively, health authorities must be able to detect a pandemic influenza strain quickly through surveillance and diagnostic efforts and use this information to administer antivirals. The effectiveness of antivirals could be limited if they are used more than 48 hours after the onset of symptoms or by the emergence of strains resistant to antivirals. Unlike antivirals, vaccines are formulated to target a specific influenza strain in advance of infection. The effectiveness of vaccines in forestalling a pandemic could be limited because such a targeted pandemic vaccine cannot be developed until that strain has been identified. Due to the time required to identify the virus and develop and manufacture a pandemic vaccine--20 to 23 weeks according to HHS--such vaccines are likely to play little or no role in efforts to forestall a pandemic in its initial phases. The availability of antivirals and vaccines in a pandemic could be inadequate due to limited production, distribution, and administration capacity. The United States, its international partners, and the pharmaceutical industry are investing substantial resources to address constraints on the availability and effectiveness of antivirals and vaccines.