WHO Updates Pandemic Flu Vaccines' Status

Regulatory authorities have licensed pandemic vaccines in Australia, China and the United States, soon to be followed by Japan and several countries in Europe, according to a Sept. 24 press release.

The length of the approval process depends on factors such as each country's regulatory pathway, the type of vaccine being licensed, and the stage of manufacturers' readiness to submit appropriate information to regulatory authorities.

In May 2009, WHO estimated that, in a best case scenario, worldwide production capacity for pandemic vaccines would be approximately 5 billion doses per year. Since then, better information on production yield and appropriate vaccine formulation has become available.

WHO currently estimates capacity at approximately 3 billion doses per year. While this figure is lower than previously projected, early data from clinical trials suggest that a single dose of vaccine will be sufficient to confer protective immunity in healthy adults and older children, effectively doubling the number of people who can be protected with current supplies.

These supplies will still be inadequate to cover a world population of 6.8 billion people in which virtually everyone is susceptible to infection by a new and readily contagious virus. Global manufacturing capacity for influenza vaccines is limited, inadequate and not readily augmented.

Pandemic vaccines have their greatest impact as a preventive strategy when administered before or near the peak incidence of cases in an outbreak. Both regulatory authorities and vaccine manufacturers have made extraordinary efforts to expedite the availability of vaccines.

Many affluent countries have previously contracted with manufacturers to obtain sufficient vaccine supplies to cover their entire populations. However, most low- and middle-income countries lack the financial resources to compete for an early share of limited supplies. Vaccine supplies in these countries will largely depend on donations from manufacturers and other countries.

Last week, donations of pandemic vaccines for use in developing countries were announced by the United States, in concert with Australia, Brazil, France, Italy, New Zealand, Norway, Switzerland and the United Kingdom. Similar support from additional countries is anticipated.

WHO will be coordinating the distribution of the donated vaccines. Distribution of the first batches of donated vaccines is expected to begin in November. WHO continues to recommend that health workers be given high priority for early vaccination.

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