MedicalResearch.com: What are the main findings of the study?
Dr. Sørup: We found that admissions with any type of infection was reduced with 14 % for Danish children having the live, attenuated vaccine against measles, mumps, and rubella (MMR) as the most recent vaccine compared with children having the inactivated vaccine against Diphtheria, Tetanus, Pertussis, Polio, and Haemophilus Influenzae type b (DTaP-IPV-Hib) as the most recent vaccine. In Denmark herd immunity against measles, mumps, and rubella is high and only 26 of the more 42,000 admissions was related to measles, mumps, and rubella; so this finding cannot be explained by the specific protection against the targeted diseases.
In Denmark MMR vaccination is recommended at 15 months of age, but only 50% of the children in the study had received MMR before 16 months of age. We estimated that one hospital admission between 16 and 24 months of age could be avoided for 201 children vaccinated with MMR before 16 months of age rather than later.
These results are based on a retrospective cohort study including approximately half a million Danish children. The analyses are adjusted for age and a long range of background factors, including socio-economic factors.
MedicalResearch.com: Were any of the findings unexpected?
Dr. Sørup: In low-income settings, it has previously been found that measles vaccine is associated with reduced risk of mortality and admissions from other causes than measles. It is an important insight that similar observations have now been made in a high-income setting.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Sørup: It is important to follow the recommended vaccination programme and particularly to receive the MMR vaccine on time. This is important for protection against the targeted diseases, but our study showed that the MMR vaccine could have a general immune stimulating effect thereby increasing protection against unrelated infections.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Sørup: It is important to evaluate vaccines and vaccination programmes both in terms of protection against the targeted diseases and in terms of general morbidity. It is important with observational studies and randomised trials from different settings to secure that we use already available vaccines in the best possible way to reduce morbidity and mortality worldwide.
Sørup S, Benn CS, Poulsen A, Krause TG, Aaby P, Ravn H. Live Vaccine Against Measles, Mumps, and Rubella and the Risk of Hospital Admissions for Nontargeted Infections. JAMA. 2014;311(8):826-835. doi:10.1001/jama.2014.470.