WHO recommendation on influenza A(H7N9) vaccine virus

Overview

Because the  A(H7N9) virus seems to transmit from animals to humans more readily than the highly pathogenic avian  influenza A(H5N1) viruses and little or no immunity against the novel virus A(H7N9) exists in the human population, WHO is actively working with its Member States and partners on effective responses and preparedness. As part of these efforts, candidate vaccine viruses are being developed and made available by the WHO GISRS. These recommendations reflect current understanding of avian influenza A(H7N9) virus causing human disease. WHO continues to monitor the situation closely for any changes that may affect the recommendations contained in this document. Should any factors change, WHO will issue a further update. The following recommendations apply to avian influenza A(H7N9) viruses causing human disease, including both highly pathogenic avian influenza (HPAI) viruses and low pathogenicity avian influenza (LPAI) viruses.