Immunogenicity and Safety of Japanese Encephalitis Vaccine When Given With Measles-Mumps-Rubella (MMR) Vaccine

Measles immunogenicity was assessed by the percentage of participants with demonstrated seropositivity for measles at 56 days post-vaccination. Seropositivity was defined by a concentration of ≥ 120 mIU/mL of anti-measles neutralizing antibody titer, as measured by the plaque reduction neutralization test (PRNT) (dilution converted to concentration using the 3rd International Standard Reference serum).

Rubella immunogenicity was assessed by the percentage of participants with demonstrated seropositivity for rubella at 56 days post-vaccination. Seropositivity was defined as antirubella immunoglobulin G (IgG) concentration of ≥ 10 IU/mL (corresponding to an optical density ratio ≥ 1.10) using a commercial IgG enzyme-linked immunosorbent assay (ELISA).

Mumps immunogenicity was assessed by the percentage of participants with demonstrated seropositivity for mumps at 56 days post-vaccination. Seropositivity was defined as an optical density ratio ≥ 1.10 using a commercial ELISA.

Anti-measles neutralizing antibody concentration was measured by the plaque reduction neutralization test (PRNT).

Anti-rubella immunoglobulin G (IgG) concentration was measured using a commercial IgG enzyme-linked immunosorbent assay (ELISA).

The seroconversion rate for measles at 56 days post-vaccination was defined as the percentage of participants with a change in serostatus from negative to positive 56 days after vaccination or a four-fold rise in concentration 56 days after vaccination if seropositive for measles at baseline. Seropositivity was defined by a concentration of ≥ 120 mIU/mL of anti-measles neutralizing antibody titer, as measured by the plaque reduction neutralization test (PRNT).

The seroconversion rate for mumps at 56 days post-vaccination was defined as the percentage of participants with a change in serostatus from negative to positive 56 days after vaccination. Seropositivity was defined as an optical density ratio ≥ 1.10, measured using a commercial ELISA. Participants with equivocal serostatus at baseline are counted as non-responders.

The seroconversion rate for rubella at 56 days post-vaccination was defined as the percentage of participants with a change in serostatus from negative to positive 56 days after vaccination or a four-fold rise in concentration 56 days after vaccination if seropositive for rubella at baseline. Seropositivity is defined as a post-vaccination concentration of ≥ 10 IU/mL measured using a commercial ELISA.

Japanese encephalitis (JE) immunogenicity was assessed by the percentage of participants with demonstrated seropositivity 28 days after CD-JEV vaccination. Seropositivity was defined as an anti-JE serum neutralizing antibody titer of ≥ 1:10, as measured by JE PRNT-50.

Anti-JE serum neutralizing antibody titer was measured using JE PRNT-50.

Participants were observed for 30 minutes after each vaccination for immediate reactions. Immediate reactions included both local (injection site) and systemic reactions. MMR vaccine was injected on left upper thigh and CD-JEV was injected on right upper thigh.

Serious reactions were those meeting one of the following conditions:

• Death.
• Life threatening
• Required inpatient hospitalization or prolongation of existing hospitalization.
• Resulted in a persistent or significant disability or incapacity.
• Important medical events that, based upon appropriate medical judgment, may jeopardize the participant and may require medical or surgical intervention to prevent one of the outcomes listed above.

Reactogenicity post-vaccination was assessed from 30 minutes through 14 days following vaccination.

Parents used a structured reactogenicity diary card to record the following solicited (pre-listed) local and system reactions.

Local reactions (at injection site):

• Ecchymosis (bruising)
• Erythema (redness)
• Edema (swelling)
• Induration (hardness)
• Pain/tenderness

Systemic reactions:

• Fever
• Rash
• Cough
• Runny nose
• Change in eating habits
• Diarrhea
• Sleepiness
• Irritability
• Unusual crying
• Vomiting

Parents recorded local reactions on a diary card.

Local ecchymosis, erythema, edema, and induration were graded as follows:

Grade 1: ≤2.5 cm in diameter.

Grade 2: >2.5 cm in diameter with 50% of surface area of extremity segment involved.

Grade 3: ≥50% surface area of extremity segment involved OR ulceration OR secondary infection OR phlebitis OR sterile abscess OR drainage.

Grade 4: potentially life-threatening (e.g., abscess, exfoliative dermatitis, necrosis involving dermis or deeper tissue).

Injection site pain/tenderness (pain without touching or tenderness when the area is touched) were graded as follows:

Grade 1: pain/tenderness causing no or minimal limitation of use of limb. Grade 2: pain/tenderness causing greater than minimal limitation of use of limb.

Grade 3: pain/tenderness causing inability to perform usual social and functional activities.

Grade 4: pain/tenderness causing inability to perform basic self-care OR hospitalization indicated.

Parents recorded systemic reactions on a diary card.

Fever was recorded and graded as follows (axillary temperature):

Grade 1: 37.5°C to 37.9°C

Grade 2: 38.0°C to 38.4°C

Grade 3: 38.5°C to 40.0°C

Grade 4: >40.0°C

Rash, cough, runny nose, change in eating habits, diarrhea, sleepiness, irritability, unusual crying, vomiting, and any other unsolicited reaction occurring from 30 minutes through 14 days post vaccination were graded as follows:

Grade 1: symptoms causing no or minimal interference with usual social and functional activities.

Grade 2: symptoms causing greater than minimal interference with usual social and functional activities.

Grade 3: symptoms causing inability to perform usual social and functional activities with intervention or hospitalization indicated.

Grade 4: symptoms causing inability to perform basic self-care functions OR medical or operative intervention indicated to prevent permanent impairment, persistent disability, or death.

Each adverse event (AE) was assessed for relationship to vaccine by the study clinician according to the following:

Definitely Related: An adverse event or unanticipated problem clearly related to the research procedures.

Possibly Related: There is a reasonable possibility that the adverse event or unanticipated problem, incident, experience, or outcome may have been caused by the procedures involved in the research.

Not Related: Any adverse event or unanticipated problem clearly not related to study procedures.

Related adverse events includes events that were assessed as definitely or possibly related.

A serious adverse event (SAE) was defined as an AE that met one of the following:

• Death
• Life threatening
• Required inpatient hospitalization or prolongation of existing hospitalization
• Resulted in persistent or significant disability or incapacity
• Important medical events that, based upon appropriate medical judgment, jeopardized the participant and required medical or surgical intervention to prevent an outcomes listed above

AEs were assessed for relationship to vaccine by the study clinician according to the following:

Definitely Related: An AE or unanticipated problem clearly related to the research procedures.

Possibly Related: There is a reasonable possibility that the AE or unanticipated problem, incident, experience, or outcome may have been caused by the procedures involved in the research.

Not Related: Any AE or unanticipated problem clearly not related to study procedures.

Related SAEs includes events that were assessed as definitely or possibly related.