Guidelines on the Use of Pandemic H1N1 Vaccines

The Committee for Medicinal Products for Human Use (CHMP) at the European Medicines Agency has reviewed early data from clinical trials for the three approved vaccines for the pandemic flu. The Committee’s conclusion was that the recommendations that had been adopted in September should still be followed. The original recommendation was that the vaccine be preferably used in two doses, and the doses should be administered at least three weeks apart. On 23 October, the London-based agency released questions and answers on the CHMP review on the recommendations on the usage of pandemic H1N1 vaccines.

The Europe Commission authorised three vaccines for the pandemic flu that can be used in Member States which fight against the infection with the virus that is the cause for the HINI pandemic, the approved vaccines are the following: • Celvapan, from Baxter AG; • Focetria, from Novartis Vaccines and Diagnostics S.r.l.; • Pandemrix, from GlaxoSmithKline Biologicals S.A.

September recommendations still apply

The recommendation from September 2009, that the H1N1 pandemic vaccines be used used in two doses, and the doses should be administered at least three weeks apart, was made on prior research conducted during the authorisation process. The three vaccines were approved using the concept of a ‘mock-up’ vaccine, that is the vaccines were authorised prior to the pandemic using data from the H5N1 strain of the flu virus (‘bird flu’). The H5N1 vaccines were approved as a two-dose schedule.

In September, the Committee acknowledged that the preliminary data for Pandemrix indicated that one dose may be sufficient in adults. Due to the fact that the clinical trials had generated limited data on the usage of the H1N1 vaccines, the CHMP has requested vaccine manufacturers to supply the Committee with data from their ongoing clinical trials on the H1N1 vaccine once the data are available. The three vaccine manufacturers have supplied the preliminary results.

The data provided investigate the immunogenicity of the vaccines, that is the the vaccines’ ability to generate a response from the immune system, the human body’s natural defence system, which allows the vaccinated person to fight infection with the H1N1 virus. The Committee reviewed immunogenicity results in vaccinated subjects three weeks after the first injection of the vaccines.

Single use dose not recommended

The CHMP noted that the data supplied to date are still limited and do not allow the Committee to recommend the general use of a single-dose vaccination schedule. For Pandemrix, the vaccine should be used as a two-dose schedule, but a single dose may be sufficient in adults aged 18 to 60 years. The immunogenicity results in healthy adults show that one dose of Pandemrix brought about an appropriate level of protection. For Focetria, the vaccine should preferably be used as a two-dose schedule, but a single dose may be sufficient in adults. For Celvapan,the dosage schedule remains as two doses with a three-week interval, in all populations.

The CHMP also noted several import points. First, the mock-up H5N1 vaccine trials contain only a limited numbers of vaccinated adults or elderly subjects. Additionally in the longer term effects are not known and studies will continue to investigate the persistence of the immune response after a single dose of the vaccine.. More data will be supplied from these clinical trials, and the Committee will review them when they become available. As a result, the dosing recommendations may change in the future.

The opinions of the CHMP on the dosing schedules for Pandemrix and Focetria are being transmitted to the European Commission for the granting of a variation to the marketing authorisations.

For more information about vaccines and the Pandemic Flu

New advice from WHO on vaccination for H1N1

Cristian Busoi MEP hosts "Pandemic Flu: Public Health Approaches" organised by Fundamed with the support of EPHA

A(H1N1)v (Swine) Influenza - Frequently Asked Questions

European Commission Proposal for a Council Recommendation on Seasonal Influenza Vaccination

**Update**Novel Influenza A/H1N1 (Swine Flu) Pandemic

How prepared are we? Novel Influenza A/H1N1 continues to spread...