Mihn Pham, United States of America
Rochester Institute of Technology School of Mathematical Sciences, College of ScienceAuthor Of 1 Presentation
SERUM ANTIBODY LEVELS TO PNEUMOCOCCAL POLYSACCHARIDES 22F, 33F, 19A AND 6A THAT CORRELATE WITH PROTECTION FROM ACUTE OTITIS IN CHILDREN IN ROCHESTER NY (ID 845)
Abstract
Background
Serotypes 22F and 33F have been added to a new 15-valent pneumococcal-conjugate vaccine (V114, Merck) because of their prevalence causing IPD. An effectiveness study to prove disease prevention for pneumococcal strains expressing 22F and/or 33F capsule would be challenging due to sample size required. A possible solution may be to demonstrate a serologic correlate of protection (COP) based on natural disease responses.
Methods
We evaluated anti-polysaccharide 22F and 33F antibody levels in 6-36 month old children before and after AOM infections caused by pneumococcal strains expressing 22F or 33F capsule. COP levels were inferred using generalized-linear models. To validate our approach testing of anti-19A and 6A antibody levels as comparators is underway.
Results
The contribution of antibody level to AOM risk was statistically significant for 22F (p=0.014) and 33F (p=0.006). We derived that a level of antibody=0.25µg/ml is a COP threshold for prevention of pneumococcal AOM infections caused by 22F and 33F strains. Among unvaccinated children 18-months olds, 62.5% had titers that exceeded this threshold for 22F.
Conclusions
We conclude that a level of antibody of 0.25μg/ml for 22F and 33F will be effective for preventing AOM in children if such levels are produced in response to V114.