Background: Accurate ascertainment of cause of death is needed to ensure validity of published data. Two systems in the US collect data on deaths related to vaccine-preventable diseases, the National Center for Health Statistics (NCHS), which publishes official death statistics in the United States, and the National Notifiable Disease Surveillance System (NNDSS). In CSTE position statement 01-ID-09, “Validation of Data Representing Deaths Due to Vaccine-Preventable Diseases,” CSTE endorsed validation of VPD-related rare deaths, using both data sources. Further, CSTE encouraged state epidemiologists and state immunization programs to actively collaborate with their state vital records office to validate rare deaths from VPDs reported to NCHS. In 2013, CSTE called for the addition of respiratory syncytial virus (RSV) to the list of rare causes of death for which validation activities are performed (position Statement 01-ID-09 “RSV-Associated Pediatric Mortality”). Methods: A protocol and data use agreement between the National Center for Immunization and Respiratory Diseases (NCIRD) and the NCHS were developed to guide validation of rare cause VPD death reports. The protocol calls for the state vital records offices that “opt-in” to query these deaths and obtain concurrence with the cause-of-death (COD) certifier within a few weeks of death registration (rather than months or years). NCHS then provides select death certificate information to NCIRD for investigation and validation with the appropriate state epidemiology and/or immunization office. Results: Between July 2012 and July 2013, 20 states opted in to this new protocol; death reports were received from 15 states. Of 26 deaths reported, 9 were validated by NCIRD, 12 were identified by NCIRD as having a COD other than the VPD, and 5 could not be investigated. Among the 12 varicella deaths reported, 2 were validated as varicella, 9 were determined to have another COD, and 1 was not able to be investigated. The 2 deaths reported as mumps and 1 reported as measles were determined to have COD other than the VPD. All 4 of the pertussis reports were validated as pertussis. Three of 6 CRS reports were validated and 3 could not be investigated. The diphtheria death report could not be investigated. Conclusions: Rare-cause validation requires cooperation of state vital records offices, COD certifiers, and NCHS staff who quickly identify deaths from rare causes. Also, investigation of death reports by state epidemiology and/or immunization programs is required to make the national death surveillance system more accurate and usable for monitoring rare deaths due to VPDs.