25 September 2009Global production capacity for H1N1 flu vaccines now stand at 3 billion doses per year, 2 billion less than projected in the spring, but potentially covering more people – even if inadequate – since a single dose may be sufficient, according to the United Nations health agency. “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,” the World Health Organization (WHO) warned in its latest update. “Global manufacturing capacity for influenza vaccines is limited, inadequate and not readily augmented.”Noting that pandemic vaccines have their greatest impact as a preventive strategy when administered before or near the peak incidence of cases in an outbreak, it praised both regulatory authorities and vaccine manufacturers for their “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, but most low- and middle-income countries lack the financial resources to compete for an early share of limited supplies, WHO said. Vaccine supplies in these countries will largely depend on donations from manufacturers and other countries.Last week, donations of pandemic vaccines for 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 and warmly welcomed,” WHO said, noting that it will be coordinating their distribution, expected to begin in November.The agency also stressed the need for early treatment with the antiviral drugs, oseltamivir or zanamivir, for patients who are at increased risk of developing complications, have severe illness or show worsening signs and symptoms.At the same time, it warned clinicians to be alert to two situations that carry a high risk for the emergence of viruses resistant to oseltamivir – in patients with severely compromised or suppressed immune systems who have prolonged illness, have received oseltamivir treatment but still have evidence of persistent viral replication; and in people who receive oseltamivir preventively after exposure to someone and then develop the illness.