A Meta-Analysis of Studies Comparing the Respiratory Route with the Subcutaneous Route of Measles Vaccine Administration

The respiratory tract has been suggested as an optimal alternative site to target measles vaccine delivery. We performed a meta-analysis to evaluate the efficacy of measles vaccine administered through the respiratory route compared to the subcutaneous route. We analyzed 20 reported results from 16 eligible studies. Seroresponse was 4% higher amongst vaccinees in the respiratory group compared to the subcutaneous group (M-H pooled RR = 1.04; 95% CI = 0.98-1.10). For vaccinees over 9 months of age, seroresponse was 15% higher in the respiratory group (M-H pooled RR = 1.15; 95% CI = 1.08 to 1.17). When Edmonston Zagreb (EZ) strain was used, the vaccine was found to be neither more nor less efficacious when administered through respiratory route (M-H pooled RR=1.00; 95% CI = 0.94 to 1.08). Seroresponse in the vaccinees receiving aerosol measles vaccine was 10% higher (M-H pooled RR = 1.10, 95% CI = 1.04-1.17) compared to those who received measles vaccine through the subcutaneous route. Seroresponse due to aerosolized EZ vaccine was 9% higher than subcutaneous EZ vaccine (M-H pooled RR = 1.09; 95% CI = 1.02-1.16). The seroresponse among seropositive vaccinees was 60% higher (M-H RR = 1.60; 95% CI = 1.40 to 1.80). The results suggest that the respiratory route of delivery of measles vaccine is at least as efficacious as measles vaccine administered through the subcutaneous route. However, more research is required on standardization of dosage, administration equipments, efficacy, and safety of respiratory (aerosol) route of administration of measles vaccine.