Vaccine response to the avian influenza A(H7N9) outbreak - step 1: development and distribution of candidate vaccine viruses

Overview

The first step in the long cycle of vaccine development and production is vaccine virus selection and the development  of  high-growth reassortants (candidate vaccine viruses (CVVs)). This is a well established process and has been in place since the 1970s. It was further strengthened during the response to A(H5N1) and pandemic A(H1N1 2009, mainly through the WHO Global Influenza Surveillance and Response System (GISRS) which currently comprises 150 laboratories in 111 countries. Since the detection of avian influenza A(H7N9) virus in China, GISRS has been on alert. Through the excellent work undertaken by the WHO Collaborating Centre (WHO CC) in Beijing, viruses have been isolated and shipped to other WHO CCs and Essential Regulatory Laboratories (ERLs) of GISRS for joint virus characterization, development of diagnostic tests, risk assessment and candidate vaccine virus development for pandemic preparedness purposes.