Can hexavalent vaccines be simultaneously administered with pneumococcal or meningococcal conjugate vaccines?

Background: Local immunization programs may include hexavalent and conjugate pneumococcal or meningococcal vaccines administered in the same vaccination visit. Information based on evidence is necessary for correctly planning schedules and for parents who often fear the administration of too many vaccines. We reviewed the available literature to assess the effects on immunogenicity and safety of simultaneous administration of hexavalent and conjugate pneumococcal and meningococcal C vaccines in healthy children.

Methods: We searched for papers including a comparison of coadministration and single administration of hexavalent with conjugate pneumococcal or meningococcal C vaccines. Data sources included Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE. Immunogenicity and safety results were extracted and compared. We calculated the absolute risk increase of being a non responder to any antigen and of experiencing common adverse events.

Results: Four relevant articles were included in the review. Immunogenicity of components included in the hexavalent vaccines was maintained with coadministration of conjugate pneumococcal and meningococcal C vaccines. However individuals who received hexavalent vaccine with conjugate pneumococcal vaccines were 18% more likely to have anti-PRP < 1 microg/mL after the third dose although this difference disappeared after the fourth dose, and titres against meningococcal C antigens were higher when vaccines were administered separately. Children who received simultaneous administration of hexavalent vaccines with conjugate pneumococcal vaccines had a 13-17% additional risk of experiencing fever compared with single administration.

Conclusion: Few studies deal with coadministration of vaccines. Hexavalent and conjugate pneumococcal or meningococcal vaccines may however be administered simultaneously without noteworthy negative effects on immunogenicity or safety profile. Parents of vaccinees should be appropriately informed on the effects of coadministration to improve their compliance. Studies on vaccine coadministration should be promoted and unpublished studies realized for vaccine registration should be made available.