1. Could Less Be More? Accounting for Fractional-Dose Regimens and Different Number of Vaccine Doses When Measuring the Impact of the RTS,S/AS01E Malaria Vaccine.
- Author
-
Westercamp, Nelli, Osei-Tutu, Lawrence, Schuerman, Lode, Kariuki, Simon K, Bollaerts, Anne, Lee, Cynthia K, Samuels, Aaron M, Ockenhouse, Christian, Bii, Dennis K, Adjei, Samuel, Oneko, Martina, Lievens, Marc, Sarfo, Maame Anima Attobrah, Atieno, Cecilia, Bakari, Ashura, Sang, Tony, Kotoh-Mortty, Maame Fremah, Otieno, Kephas, Roman, François, and Buabeng, Patrick Boakye Yiadom
- Subjects
MALARIA vaccines ,CLINICAL trial registries ,VACCINE effectiveness ,VACCINATION of children ,RABIES vaccines - Abstract
Background The RTS,S/AS01
E (RTS,S) malaria vaccine is recommended for children in malaria endemic areas. This phase 2b trial evaluates RTS,S fractional- and full-dose regimens in Ghana and Kenya. Methods In total, 1500 children aged 5–17 months were randomized (1:1:1:1:1) to receive RTS,S or rabies control vaccine. RTS,S groups received 2 full RTS,S doses at months 0 and 1 and either full (groups R012-20, R012-14-26) or fractional doses (one-fifth; groups Fx012-14-26, Fx017-20-32). Results At month 32 post-dose 1, vaccine efficacy against clinical malaria (all episodes) ranged from 38% (R012-20; 95% confidence interval [CI]: 24%–49%) to 53% (R012-14-26; 95% CI: 42%–62%). Vaccine impact (cumulative number of cases averted/1000 children vaccinated) was 1344 (R012-20), 2450 (R012-14-26), 2273 (Fx012-14-26), and 2112 (Fx017-20-32). To account for differences in vaccine volume (fractional vs full dose; post hoc analysis), we estimated cases averted/1000 RTS,S full-dose equivalents: 336 (R012-20), 490 (R012-14-26), 874 (Fx012-14-26), and 880 (Fx017-20-32). Conclusions Vaccine efficacy was similar across RTS,S groups. Vaccine impact accounting for full-dose equivalence suggests that using fractional-dose regimens could be a viable dose-sparing strategy. If maintained through trial end, these observations underscore the means to reduce cost per regimen thus maximizing impact and optimizing supply. Clinical Trials Registration NCT03276962 (ClinicalTrials.gov). [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF