WHO Reports Some Promising Results on Avian Influenza Vaccines

Experts meeting over the past two days at the World Health Organization (WHO) on advances in pandemic influenza vaccine development reported encouraging progress.

Sixteen manufacturers from 10 countries are developing prototype pandemic influenza vaccines against H5N1 avian influenza virus. Five of them are also involved in the development of vaccines against other avian viruses (H9N2, H5N2, and H5N3).

At present, more then 40 clinical trials have been completed or are ongoing. Most of them have focused on healthy adults. Some companies, after completing safety analyses in adults, have initiated clinical trials in the elderly and in children. All vaccines were safe and well tolerated in all age groups tested.

For the first time, results presented at the meeting have convincingly demonstrated that vaccination with newly developed avian influenza vaccines can bring about a potentially protective immune response against strains of H5N1 virus found in a variety of geographical locations. Some of the vaccines work with low doses of antigen, which means that significantly more vaccine doses can be available in case of a pandemic.

These developments were discussed at the WHO meeting on the evaluation of pandemic influenza prototype vaccines in clinical trials that took place in Geneva, Switzerland, on 15-16 February 2007. This was a third such meeting in just two years and its objectives were to review progress in the development of candidate vaccines against pandemic influenza viruses and to reach consensus on future priority activities.

More than 100 influenza vaccine experts