Table 1. Advantages and disadvantages of recombinant modified vaccinia virus Ankara vaccines and implication for pandemic influenza vaccine development.

Advantage	Implication for influenza vaccine production	Disadvantage	Implication for influenza vaccine production
Production
Independent of embryonated chicken eggs, in (stockpiled) CEF cells	Flexible vaccine production	Use of primary/secondary CEF cells	Higher risk for adventitious agent contamination
Safe, BSL-1 conditions	Ease of manufacturing
Option to upscale	Increase production capacity
Efficacy
Induction of strong antibody responses	Use of adjuvant is not required	High dose required	Increased costs
Induction of cross-reactive antibodies	Protection against antigenically distinct variants
Induction of T-cell responses	Possibility for broadly protective immunity
No interference by pre-existing vector immunity	Allows for repeated vaccination and induction of antibodies to multiple influenza virus antigens
Safety
Replication deficiency and avirulence	Acceptable safety profile
Administration to immunocompromized individuals	Vaccination of these high-risk patients possible
Multivalent vaccines possible	Induction of virus-specific antibodies and T cell Expression of multiple HA genes to induce broad protective antibody responses
Stability
Record for stability as lyophilized vaccine >4 weeks at 37°C*	Stockpiling of vaccines possible

^*Taken from [61].

CEF: Chicken embryo fibroblast; HA: Hemagglutinin.