Influenza A (H1N1) 2009 was a novel virus first detected in April 2009. The existing trivalent seasonal influenza vaccines show little cross-protection for this virus. Since it takes at least five to six months to produce a vaccine after identification of a vaccine strain virus, vaccines were not available for containment of pandemic H1N1 influenza. The first vaccines against H1N1 virus were licensed in September 2009. However, vaccines were anticipated to have an important role as one of the most important components of the mitigation strategy for the current pandemic.
The three key objectives of vaccination during the current pandemic include:
(1) to protect the integrity of the health care system and a country’s critical infrastructure;
(2) to reduce morbidity and mortality; and
(3) to reduce transmission of the pandemic virus within communities.
Many organizations including the United States Centers for Disease Control and Prevention Advisory Committee on Immunization Practices, European Centre for Disease Prevention and Control and the World Health Organization Strategic Advisory Group of Experts on Immunization have issued recommendations on prioritization of population groups for receiving pandemic H1N1 vaccine.
On 15 September 2009, the United States Food and Drug Administration (FDA) announced its approval of four pandemic (H1N1) 2009 vaccines from the following manufacturers: CSL Limited; MedImmune LLC; Novartis Vaccines and Diagnostics Limited; and Sanofi Pasteur Inc. In addition, Australia and China have also licensed a domestically produced pandemic H1N1 vaccine. Since 29 September 2009, three pandemic (H1N1) 2009 vaccines, produced by Novartis Vaccines and Diagnostics, GlaxoSmithKline (GSK) Biologicals and Baxter AG, have been authorized by the European Commission.
The current annual global capacity for pandemic H1N1 vaccine remains limited at an estimated 3 billion doses. WHO is mobilizing support from manufacturers and developed countries to ensure access to vaccines for at least 10% of priority populations in developing countries. As of October 2009, WHO has received pledges for about 190 million doses from five major manufacturers (GSK, CSL, MedImmune, Sanofi Pasteur and Novartis) and fourteen developed countries. Seventeen countries and areas in Western Pacific Region may receive vaccine donation from WHO.
The pandemic H1N1 vaccines have been produced using the same manufacturing processes as the seasonal influenza vaccines in use since 1950s and have similar safety profiles.