If WHO considers that the planned change(s) will result in a product or application information of substantial difference to that which was prequalified, WHO will notify the manufacturer that a new application for WHO prequalification is required. WHO will also notify the manufacturer on the impact of the planned change to the prequalification status of the product. The changes listed below are examples of those that could require submission of a new application for prequalification:

• a change to what is detected (i.e. the analyte or measurand)
• changes in antigens, antibodies, primers or solid phase
• a change to the specific disorder, condition or risk factor of interest that the IVD is intended to detect, define or differentiate
• a change in the test result format from qualitative to quantitative or vice versa
• a change in biological or chemical principle of the test
• a change in design of test technology.

The combination of several changes can result in the need for a new prequalification application. Manufacturers should contact seek WHO (by emailing diagnostics@who.in) when planning to introduce several changes at the same time.