The Effects of Increased Inoculum on Oral Rotavirus Vaccine Take and Immunogenicity

University of Vermont220 enrolled

Overview

Rotavirus is the leading cause of diarrhea in children worldwide. Oral rotavirus vaccines work remarkably well in high-income countries, but for unclear reasons they underperform in low-income countries. A double-blind, randomized control trial will be performed to evaluate whether using a higher dose of a currently licensed vaccine (Rotarix, GlaxoSmithKline) can improve immune responses among infants in Dhaka, Bangladesh. Infants will be randomized 1:1 to receive either a standard or a double dose of Rotarix at 6 and 10 weeks of life. Infants will be assessed for fecal vaccine shedding and serum rotavirus-specific IgA responses to determine vaccine immunogenicity.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

QUADRUPLE

Enrollment

220

Conditions

Rotavirus Infection Vaccine Response Impaired Vaccine Virus Shedding

Interventions

Eligibility

Sex: ALLMax age: 15 WeeksHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: 1. Generally healthy infant (as determined by medical officers) 2. Age 0-7 days at enrolment 3. Mother willing and able to provide signed informed consent 4. Mother willing to allow infant to be vaccinated according to study schedule 5. Mother willing to allow biological specimens, including blood, stool, and saliva, to be collected from infant according to study protocol 6. Mother willing and able to adhere to study schedule Exclusion Criteria: 1. Obvious congenital malformation 2. Birth weight (if known) or enrolment weight (if birth weight unknown) \< 2000 gm 3. Known immunocompromising condition in infant 4. Enrolment in other vaccine research trials 5. Other household member enrolled in this study

Outcomes

Primary Outcomes

Number (or Percentage) of Infants in Each Study Arm Who Test Positive for Fecal Rotavirus Vaccine-strain Virus Shedding Post-vaccination

This will be an aggregate measure demonstrating a change from baseline. Infants will have stool collected immediately prior to Rotarix vaccination at weeks 6 and 10 of life, then 4, 7, and 14 days following each dose (i.e. last assessment at week 12 of life). Each specimen will be assessed for vaccine-strain virus (i.e. fecal vaccine shedding) at each time point by polymerase chain reaction. Any child who has a change in fecal vaccine shedding status, from negative at baseline (6 weeks) to positive at any subsequent time point, will be categorized as having met the outcome measure for positive fecal vaccine shedding.

Time frame: Measured through week 12 of life

Number (or Percentage) of Infants in Each Study Arm With Rotavirus-specific Plasma Immunoglobulin A (IgA) Seroconversion Post-vaccination

This outcome will measure seroconversion, i.e. the change in plasma rotavirus-specific IgA concentration at week 14 of life compared to week 6 of life (baseline). Blood will be collected from infants prior to the first dose of Rotarix at week 6 of life and again at week 14 of life (4 weeks following the second dose) for measurement of plasma rotavirus-specific IgA by enzyme immunoassay. Infants will be assessed for seroconversion (IgA concentration \<=20 U/mL pre-vaccination and \>20 post-vaccination). Infants who demonstrate rotavirus-specific IgA seroconversion will be categorized as having met the outcome measure.

Time frame: Measured at week 14 of life

Number (or Percentage) of Infants in Each Study Arm With Successful Vaccine Take, Defined as Positive Fecal Vaccine Shedding Post-vaccination OR Rotavirus-specific Plasma IgA Seroconversion Post-vaccination

Vaccine take is an aggregate, dichotomous immunogenicity measure (successful vaccine take vs no vaccine take). Infants positive for either fecal vaccine shedding OR plasma rotavirus-specific IgA seroconversion (as described in Outcomes 1 and 2, respectively) will be categorized as having met the outcome measure of successful vaccine take. Those who met neither outcome will be categorized as no vaccine take.