The US FDA has said it needs more time to review a vaccine against the influenza H5N1 strain developed by GlaxoSmithKline (GSK) because of an “administrative” issue.
The agency issued a complete response letter to GSK regarding its application to market the pandemic flu vaccine – called Q-Pan H5N1 – over the administrative issue, which the company says has now been rectified.
According to agency regulations, the FDA had been scheduled to conclude its review for the vaccine in December 2012, and at the moment the likely length of the delay is unknown. If approved, Q-Pan H5N1 is to be used only according to official guidance from the US government.
“GSK and the FDA are actively working together to complete the review in a timely manner,” said the pharma company in a statement.
Last November an FDA advisory committee voted unanimously that the safety and immunogenicity data of the H5N1 vaccine supports its approval in adults.
The ‘bird flu’ vaccine was submitted for US approval in March last year and is intended for active immunisation in adults at least 18 years old for the prevention of disease after exposure to the H5N1 influenza strain. It is a two-component vaccine consisting of inactivated A/H5N1 influenza virus antigen and GSK’s AS03 adjuvant.
That vaccine was approved in March 2011 in Europe, where it is marketed under the brand name Pumarix, with GSK’s biologics unit awarded a five-year marketing authorisation from the European Commission.
The World Health Organization (WHO) maintains a pandemic alert for the H5N1 strain, in part because it is associated with a very high mortality rate of around 60 per cent. Although it is not readily transmissible between birds and humans, there continue to be concerns that it could mutate and spread more widely.
H5N1 first emerged in humans in 1997 in China and Hong Kong, and re-emerged in Asia, Europe and Africa in 2003 and 2004. It remains on the pandemic watch list because it continues to circulate widely in poultry populations and most humans lack immunity to the strain.