715. Randomized, Double-Blind, Placebo-Controlled, Proof-of-Concept Study in US to Evaluate the Safety and Immunogenicity of RotaTeq™ in Healthy Elderly Subjects
Session: Poster Abstract Session: Vaccine Studies, Adjuvants, and Discovery
Friday, October 21, 2011
Room: Poster Hall B1

Background: RotaTeq™ was approved for the prevention of rotavirus (RV) gastroenteritis in infants in the US in 2006 and subsequently in >100 countries globally.  To explore the potential of expanding public health benefit of the vaccine to elderly, a study was conducted to assess the safety and immunogenicity of RotaTeq™ in adults ³65 years.

Methods: Generally healthy subjects, 65-80 years old and living outside any long-term care facility, were randomized (2:1) to receive 3 doses of RotaTeq™/placebo given 28-42 days apart. Subjects were followed for adverse events (AEs) through 42 days after vaccination. All serious AEs (SAEs) were collected through 6 months following final dose. Fecal vaccine-virus shedding was assessed. Serum anti-RV IgA and serum neutralizing antibody (SNA) responses to RV serotypes G1, G2, G3, G4, and P1A[8] were evaluated after each dose.

Results: 66 subjects were randomized; 40/44 vaccine and 21/22 placebo recipients completed the full 3-dose regimen. No subjects discontinued due to vaccine-related (VR) AEs. No VR-SAEs or VR Grade-4 AEs were reported. A higher percent of vaccine recipients (59.1%) reported AEs compared with placebo recipients (40.9%) [risk difference: 18.2%(95% CI: -7.4, 41.4)]. Diarrhea, nausea, fatigue, myalgia, and headache were the most commonly reported AEs. However, none of the risk differences were statistically significant. No confirmed cases of fecal vaccine-virus shedding were detected. Subjects had similar pre-existing antibodies to rotavirus [geometric mean titers (95% CI) for serum anti-RV IgA were 679.6 (464.5, 994.2) in RotaTeq™ and 578.4 (361.1, 926.4) in placebo recipients]. In all immunologic assays, post-vaccination responses were higher in vaccine than in placebo group. Vaccine recipients had geometric mean fold rises of 1.4-2.8 in anti-RV IgA and SNA; 15-42% achieved ³3-fold increase in titer post-vaccination. The incremental change was greatest after the first dose of RotaTeq™ with minimal changes after doses 2 and 3.  

Conclusion: RotaTeq™ is generally well tolerated and immunogenic in subjects 65-80 years of age. Despite older age and pre-existing antibodies to rotavirus, vaccination with RotaTeq™ boosted immune responses in this population after one dose.


Subject Category: I. Adult and Pediatric Vaccines

Jody Lawrence, MD1, Su He1, Jason Martin1 and Alexander Murray, MD2, (1)Merck Research Laboratories, North Wales, PA, (2)PharmQuest, Greensboro, NC

Disclosures:

J. Lawrence, Merck & Co., Inc.: Employee, Salary

S. He, Merck & Co., Inc.: Employee, Salary

J. Martin, Merck & Co., Inc.: Employee, Salary

A. Murray, Merck & Co., Inc.: Investigator, Merck sponsored clinical trial

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.