Documented vaccination as proof of immunity compared to serology in medical students

We analyzed immunity to vaccine-preventable diseases and the predictive value of documented vaccination versus serological results for medical students in Catalonia (Spain). Epidemiological study of antibody seroprevalence and vaccination in medical students at four teaching units of medicine. Blood samples were drawn from participants who completed an epidemiology questionnaire. For seven diseases, we calculated the positive predictive value (PPV) percentages (and 95% CI) reflecting the protection afforded by self-reported vaccination histories compared to serology results. We enrolled 146 medical students (participation 25.7%; 146/569), 79.5% (116/146) women, mean (SD) age 22.6 (1.6) years. Most students (84.2%; 123/146) were fully vaccinated, 18 were unaware of their vaccination status, and 5 students were not vaccinated. Of the six overseas students, only three could document their vaccination status (OR = 6.0; 95% CI: 1.1-31.8). In documented vaccination terms, PPVs for immunological protection were high for varicella (100%), COVID-19 (99.1%), hepatitis A (98.9%), and rubella (94.8%), but was substantially lower for measles (90.0%), mumps (85.9%), and hepatitis B (67.2%). The predictive value of documented vaccination history compared to serology as proof of immunity was above 90% for most vaccines except for measles, mumps, and hepatitis B.