At least once a year, samples of lots supplied through UN agencies will be selected for testing by WHO-contracted laboratories of final product characteristics. The manufacturer will be asked to provide an appropriate number of samples (between 25 and 200, depending on the vaccine type and presentation offered) of three to five lots selected by WHO from a list of products supplied to UN agencies.

Manufacturer are also requested to provide lot summary protocols and the national regulatory authority (NRA)/national control laboratory release certificate, as appropriate, for review. Manufacturers should commit to keeping an adequate number of retention samples for this testing programme.

Manufacturers will, in any case, be contacted for follow-up actions if they fail to meet specifications. In the event of failure to meet the established criteria, WHO will investigate the problem and provide the relevant UN agency with written information on the actions that need to be taken, copied to the manufacturer and the NRA.