Immunogenicity of the RTS,S/AS01 malaria vaccine and implications for duration of vaccine efficacy: secondary analysis of data from a phase 3 randomised controlled trial.
White, Michael T;
Verity, Robert;
Griffin, Jamie T;
Asante, Kwaku Poku;
Owusu-Agyei, Seth;
Greenwood, Brian;
Drakeley, Chris;
Gesase, Samwel;
Lusingu, John;
Ansong, Daniel;
+28 more...Adjei, Samuel;
Agbenyega, Tsiri;
Ogutu, Bernhards;
Otieno, Lucas;
Otieno, Walter;
Agnandji, Selidji T;
Lell, Bertrand;
Kremsner, Peter;
Hoffman, Irving;
Martinson, Francis;
Kamthunzu, Portia;
Tinto, Halidou;
Valea, Innocent;
Sorgho, Hermann;
Oneko, Martina;
Otieno, Kephas;
Hamel, Mary J;
Salim, Nahya;
Mtoro, Ali;
Abdulla, Salim;
Aide, Pedro;
Sacarlal, Jahit;
Aponte, John J;
Njuguna, Patricia;
Marsh, Kevin;
Bejon, Philip;
Riley, Eleanor M;
Ghani, Azra C;
(2015)
Immunogenicity of the RTS,S/AS01 malaria vaccine and implications for duration of vaccine efficacy: secondary analysis of data from a phase 3 randomised controlled trial.
The Lancet infectious diseases, 15 (12).
pp. 1450-1458.
ISSN 1473-3099
DOI: https://doi.org/10.1016/S1473-3099(15)00239-X
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BACKGROUND: The RTS,S/AS01 malaria vaccine targets the circumsporozoite protein, inducing antibodies associated with the prevention of Plasmodium falciparum infection. We assessed the association between anti-circumsporozoite antibody titres and the magnitude and duration of vaccine efficacy using data from a phase 3 trial done between 2009 and 2014. METHODS: Using data from 8922 African children aged 5-17 months and 6537 African infants aged 6-12 weeks at first vaccination, we analysed the determinants of immunogenicity after RTS,S/AS01 vaccination with or without a booster dose. We assessed the association between the incidence of clinical malaria and anti-circumsporozoite antibody titres using a model of anti-circumsporozoite antibody dynamics and the natural acquisition of protective immunity over time. FINDINGS: RTS,S/AS01-induced anti-circumsporozoite antibody titres were greater in children aged 5-17 months than in those aged 6-12 weeks. Pre-vaccination anti-circumsporozoite titres were associated with lower immunogenicity in children aged 6-12 weeks and higher immunogenicity in those aged 5-17 months. The immunogenicity of the booster dose was strongly associated with immunogenicity after primary vaccination. Anti-circumsporozoite titres wane according to a biphasic exponential distribution. In participants aged 5-17 months, the half-life of the short-lived component of the antibody response was 45 days (95% credible interval 42-48) and that of the long-lived component was 591 days (557-632). After primary vaccination 12% (11-13) of the response was estimated to be long-lived, rising to 30% (28-32%) after a booster dose. An anti-circumsporozoite antibody titre of 121 EU/mL (98-153) was estimated to prevent 50% of infections. Waning anti-circumsporozoite antibody titres predict the duration of efficacy against clinical malaria across different age categories and transmission intensities, and efficacy wanes more rapidly at higher transmission intensity. INTERPRETATION: Anti-circumsporozoite antibody titres are a surrogate of protection for the magnitude and duration of RTS,S/AS01 efficacy, with or without a booster dose, providing a valuable surrogate of effectiveness for new RTS,S formulations in the age groups considered. FUNDING: UK Medical Research Council.
