<prompt> Most common cause of Vaccine failure is:Improper storageImproper administrationInappropriate manufacturingMaternally derived antibodies  <response>: - Primary vaccination failure: Failure to serologically respond to vaccine: Too young age where Maternal antibodies interfere MC Cause Vaccine production problems Cold chain failure Inappropriate administration technique Immunodeficiency Poor health - Secondary vaccination failure: Waning immunity where there is loss of vaccine induced protection in an individual who had previously seroconveed to vaccination. Causes are not well understood. 