"Children who have received no vaccines: who are they and where do they live?"

#1-"Fatality Rates of Smallpox in the Vaccinated and Unvaccinated"

https://www.bmj.com/content/1/3498/116.1?tab=related

#2-"Immunology and Vaccine-Preventable Diseases – Pink Book - Polio"

https://www.cdc.gov/vaccines/pubs/pinkbook/downloads/polio.pdf

#3-"Children who have received no vaccines: who are they and where do they live?"

https://www.ncbi.nlm.nih.gov/pubmed/15231927

#4- Refer to #1.