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Safety and Differential Antibody and T-Cell Responses to the Plasmodium falciparum Sporozoite Malaria Vaccine, PfSPZ Vaccine, by Age in Tanzanian Adults, Adolescents, Children, and Infants.

Authors :
Jongo SA
Church LWP
Mtoro AT
Chakravarty S
Ruben AJ
Swanson PA
Kassim KR
Mpina M
Tumbo AM
Milando FA
Qassim M
Juma OA
Bakari BM
Simon B
James ER
Abebe Y
Kc N
Saverino E
Gondwe L
Studer F
Fink M
Cosi G
El-Khorazaty J
Styers D
Seder RA
Schindler T
Billingsley PF
Daubenberger C
Sim BKL
Tanner M
Richie TL
Abdulla S
Hoffman SL
Source :
The American journal of tropical medicine and hygiene [Am J Trop Med Hyg] 2019 Jun; Vol. 100 (6), pp. 1433-1444.
Publication Year :
2019

Abstract

In 2016, there were more cases and deaths caused by malaria globally than in 2015. An effective vaccine would be an ideal additional tool for reducing malaria's impact. Sanaria <superscript>®</superscript> PfSPZ Vaccine, composed of radiation-attenuated, aseptic, purified, cryopreserved Plasmodium falciparum (Pf) sporozoites (SPZ) has been well tolerated and safe in malaria-naïve and experienced adults in the United States and Mali and protective against controlled human malaria infection with Pf in the United States and field transmission of Pf in Mali, but had not been assessed in younger age groups. We, therefore, evaluated PfSPZ Vaccine in 93 Tanzanians aged 45 years to 6 months in a randomized, double-blind, normal saline placebo-controlled trial. There were no significant differences in adverse events between vaccinees and controls or between dosage regimens. Because all age groups received three doses of 9.0 × 10 <superscript>5</superscript> PfSPZ of PfSPZ Vaccine, immune responses were compared at this dosage. Median antibody responses against Pf circumsporozoite protein and PfSPZ were highest in infants and lowest in adults. T-cell responses were highest in 6-10-year olds after one dose and 1-5-year olds after three doses; infants had no significant positive T-cell responses. The safety data were used to support initiation of trials in > 300 infants in Kenya and Equatorial Guinea. Because PfSPZ Vaccine-induced protection is thought to be mediated by T cells, the T-cell data suggest PfSPZ Vaccine may be more protective in children than in adults, whereas infants may not be immunologically mature enough to respond to the PfSPZ Vaccine immunization regimen assessed.

Details

Language :
English
ISSN :
1476-1645
Volume :
100
Issue :
6
Database :
MEDLINE
Journal :
The American journal of tropical medicine and hygiene
Publication Type :
Academic Journal
Accession number :
30994090
Full Text :
https://doi.org/10.4269/ajtmh.18-0835