Immunogenicity of subcutaneous versus intramuscular Oka/Merck varicella vaccination in healthy children.

To compare the immunogenicity and safety of varicella vaccine by either subcutaneous or intramuscular injection, 166 healthy children aged 12 months to 10 years old who had no prior history of varicella were enrolled from two pediatric practices and randomly assigned to receive 0.5 mL of a single lot of varicella vaccine. Sera from the day of and 6 weeks postvaccination were tested for varicella antibody by gpELISA. Parents recorded clinical events occurring in the 6 weeks following vaccination. In the 132 evaluable children, the mean prevaccination titer was 0.3 gpELISA units for both groups. Sixty-three (97%) of the 65 receiving varicella vaccine by the subcutaneous route seroconverted compared with 67 (100%) of 67 immunized intramuscularly. Postvaccination geometric mean titer in the subcutaneous group was 6.9 +/- 7.0 gpELISA units and did not differ significantly from the geometric mean titer of 10.5 +/- 4.4 in the intramuscular group. Varicella vaccine was generally well tolerated by either route; 21% of both groups complained of reactions at the injection site and 7% had a varicella-like rash. Although varicella vaccine is recommended to be given subcutaneously, the results of this study indicate that inadvertent intramuscular administration of varicella vaccine is not reason for revaccination.

RCT Entities:   Population Interventions Outcomes