Dose-sparing AI vaccine supports global supply

The vaccine containing inactivated whole particles of the virulent H5N1 avian influenza strain evoked good immune responses at low doses in early clinical trials, the researchers found.

The vaccine was safe, and was most effective at eliciting virus-specific antibodies if given in two doses with aluminum hydroxide adjuvant four weeks apart, reported Jiangtao Lin and colleagues of the Chinese-Japanese Friendship Hospital in Beijing.

“These findings identify a potential dose-sparing approach that could be crucial for a global supply of pandemic vaccine,” said Iain Stephenson of the Leicester Royal Infirmary, in England.

Foreseeing a shortage of vaccine should the pandemic H5N1 strain of avian flu leap from birds to humans, the World Health Organisation has advocated investigations into dose-sparing strategies, such as the use of whole-virion vaccine and adjuvants.

The researchers say that the best approach to vaccinating against AI may be one that combines the powerful immunogenicity of a whole inactivated virus with adjuvant boosting.

The whole virion approach also preserves the estimated 20% to 30% of antigens typically lost during the split-vaccine manufacturing process, thereby making more vaccine available.

“Our trial suggests that an H5N1 vaccine manufactured and formulated with both of these approaches is well tolerated and immunogenic,” they said.