Increase in hospital admissions for infections following simultaneous vaccination with MMR and DTaP-IPV-Hib among Danish children

New research from CVIVA shows that Danish children, who have received the live MMR vaccine together with the non-live DTaP-IPV-Hib vaccine, are admitted to hospital with infections more frequently than Danish children who have received the MMR vaccine alone as recommended.

Danish children are recommended the live MMR vaccine to protect them against measles, mumps, and rubella and the non-live DTaP-IPV-Hib vaccine to protect them against diphtheria, tetanus, pertussis, polio, and Haemophilus influenzae type b. According to the vaccination schedule, children should receive the three doses of DTaP-IPV-Hib vaccine at 3, 5 and 12 months of age, followed by MMR vaccine at 15 months of age. However, not all children follow this recommendation, resulting in some children receiving MMR and DTaP-IPV-Hib together (about 1% of the children in this study).

 A new study from CVIVA shows that children, who have received MMR and DTaP-IPV-Hib together, have 7% higher risk of admissions with any type of infection compared with children who have received MMR after DTaP-IPV-Hib. This association was explained by a 27% higher risk of admission with lower respiratory infections; there was no difference for other types of infections. These effects are not related to the specific disease protection of the vaccines.

The new study was inspired by studies from low-income countries that have reported that receiving a live and a non-live vaccine together was related to higher childhood mortality compared with receiving first the non-live vaccine and thereafter the live vaccine on separate occasions. This may be related to the so-called “non-specific effects” of vaccines. 

For now, the study supports that Danish children should follow the recommended schedule and receive their vaccines on time. The study furthermore supports that it is important to conduct more studies to examine whether indeed there are different effects on overall health of receiving live vaccines and non-live vaccines alone and in combination.

A study of more than half a million Danish children

The new CVIVA study is a nationwide register-based cohort study including 520,859 Danish children. . In total, all included children experienced 71,766 hospital admissions for any infection (and only 53 related to any of the vaccine-targeted diseases) between 15 months and 4 years of age. The analyses were controlled for a range of factors related both to the risk of receiving MMR and DTaP-IPV-Hib together as well as the risk of admissions with infection like age, family characteristics, previous admissions, and birth weight.

Read the scientific article in Vaccine:
Simultaneous vaccination with MMR and DTaP-IPV-Hib and rate of hospital admissions with any infections: A nationwide register based cohort study
Signe Sørup, Christine S. Benn, Anja Poulsen, Tyra G. Krause, Peter Aaby, Henrik Ravn


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