TABLE 6. Seroprotection rates in children at 1 month after a 2-dose primary series of inactivated Vero cell culture–derived Japanese encephalitis vaccine administered according to the dose and schedule approved by the Food and Drug Administration*.
| Study site | Age group | Seroprotection rate† |
|||||
|---|---|---|---|---|---|---|---|
| 0.25-mL JE-VC dose |
0.5-mL JE-VC dose |
||||||
| Total | No. seroprotected | (%) | Total | No. seroprotected | (%) | ||
| Philippines |
2 mos–17 yrs |
148
|
147 |
(99)§ |
237
|
237 |
(100) |
| India |
1–2 yrs |
23
|
22 |
(96) |
—
|
— |
—¶ |
| United States, Europe, Australia | 2 mos–17 yrs | 5 | 5 | (100) | 57 | 57 | (100) |
Sources: Food and Drug Administration. Ixiaro: Japanese encephalitis vaccine, inactivated, adsorbed [package insert]. Vienna, Austria: Valneva Austria GmbH; 2018. https://www.fda.gov/media/75777/download; Dubischar KL, Kadlecek V, Sablan JB, et al. Immunogenicity of the inactivated Japanese encephalitis virus vaccine IXIARO in children from a Japanese encephalitis virus-endemic region. Pediatr Infect Dis J 2017;36:898–904; Kaltenböck A, Dubischar-Kastner K, Schuller E, Datla M, Klade CS, Kishore TS. Immunogenicity and safety of IXIARO (IC51) in a Phase II study in healthy Indian children between 1 and 3 years of age. Vaccine 2010;28:834–9; Jelinek T, Cromer MA, Cramer JP, et al. Safety and immunogenicity of an inactivated Vero cell–derived Japanese encephalitis vaccine (IXIARO®, JESPECT®) in a pediatric population in JE non-endemic countries: An uncontrolled, open-label phase 3 study. Travel Med Infect Dis 2018;22:18–24.
Abbreviations: FDA = Food and Drug Administration; JE-VC = Vero cell culture–derived Japanese encephalitis vaccine.
* For children aged 2 months–2 years, 2 doses (0.25 mL each) administered 28 days apart; for children aged 3–17 years, 2 doses (0.5 mL each) administered 28 days apart.
† Proportion with 50% plaque reduction neutralization test titer ≥10.
§ Of an additional 98 children aged 3–11 years who received 2 doses of 0.25 mL, 94 (96%) were seroprotected at 1 month after the second dose.
¶ Of 21 children aged 1–2 years who received 2 doses of 0.5 mL, 20 (95%) were seroprotected at 1 month after the second dose; the FDA-approved dose for children aged 1–2 years is 0.25 mL.