Increasing the Time of Exposure to Aerosol Measles Vaccine Elicits an Immune Response Equivalent to That Seen in 9-Month-Old Mexican Children Given the Same Dose Subcutaneously

Facultad de Medicina, Departamento de Medicina Experimental, Universidad Nacional Autónoma de México.
The Journal of Infectious Diseases (Impact Factor: 6). 08/2011; 204(3):426-32. DOI: 10.1093/infdis/jir278
Source: PubMed


A 30-second aerosol measles vaccination successfully primes children 12 months of age and older but is poorly immunogenic when given to 9-month-old children. We examined the immune responses when increasing the duration to aerosol exposure in 9-month-olds.
One hundred and thirteen healthy 9-month-old children from Mexico City were enrolled; 58 received aerosol EZ measles vaccine for 2.5 minutes and 55 subcutaneously. Measles-specific neutralizing antibodies and cellular responses were measured before and at 3 and 6 months postimmunization.
Adaptive immunity was induced in 97% after aerosol and 98% after subcutaneous administration. Seroconversion rates and GMCs were 95% and 373 mIU/mL (95% confidence interval [CI], 441-843) following aerosol vaccination and 91% and 306 mIU/mL (95% CI, 367-597) after subcutaneous administration at 3 months. The percentage of children with a measles-specific stimulation index ≥3 was 45% and 60% in the aerosol versus 55% and 59% in the subcutaneous group at 3 and 6 months, respectively. CD8 memory cell frequencies were higher in the aerosol group at 3 months compared with the subcutaneous group. Adverse reactions were comparable in both groups.
Increasing exposure time to aerosol measles vaccine elicits immune responses that are comparable to those seen when an equivalent dose is administered by the subcutaneous route in 9-month-old infants.

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    • "Other investigators studied 1-year-old children [8] and 9-month-old infants, finding a lower serological response to the Edmonston Zagreb (EZ) measles strain when applied in aerosol form than when administered by injection [9]. These authors also recently reported that an increase in the exposure time to the aerosolized vaccine was associated with an elevated humoral and cellular response in children aged 9 months [10]. In one study, rubella monovalent vaccine (RA 27/3) was administered either by aerosol or by injection to children 6–7 years of age; the difference in the seroresponses to the aerosolized vaccine (61.5%) or the injection (44.0%) was not statistically significant. "
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