Long-term incidence of severe malaria following RTS,S/AS01 vaccination in children and infants in Africa: an open-label 3-year extension study of a phase 3 randomised controlled trial

Tinto, Halidou; Otieno, Walter; Gesase, Samwel; Sorgho, Hermann; Otieno, Lucas; Liheluka, Edwin; Valéa, Innocent; Sing’oei, Valentine; Malabeja, Anangisye; Valia, Daniel; Wangwe, Anne; Gvozdenovic, E.; Mendoza, Yolanda Guerra; Jongert, Erik; Lievens, Marc; Roman, François; Schuerman, Lode; Lusingu, John

doi:10.1016/s1473-3099(19)30300-7

Cited by 51 publications

(45 citation statements)

References 10 publications

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“…It was hypothesized that the primary vaccination had prevented vaccinees from acquiring natural immunity, as has been predicted for other malaria prevention tools 16 , increasing the risk of severe malaria in those individuals in whom infection reached the erythrocytic stage. However, on a longer follow-up study of up to 7 years on 3 of 11 sites, no increased risk was found for severe malaria between those groups that received the RTS,S/AS01 vaccine and the control group 31 . Antibody responses to asexual blood stage antigens have been studied previously with samples from phase 2 clinical trials and showed a reduced antibody response in RTS,S vaccinees, but these trials did not include a booster dose 17,32,33 .…”

Section: Discussionmentioning

confidence: 82%

Antibody responses to the RTS,S/AS01E vaccine and Plasmodium falciparum antigens after a booster dose within the phase 3 trial in Mozambique

et al. 2020

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The RTS,S/AS01 E vaccine has shown consistent but partial vaccine efficacy in a pediatric phase 3 clinical trial using a 3-dose immunization schedule. A fourth-dose 18 months after the primary vaccination was shown to restore the waning efficacy. However, only total IgG against the immunodominant malaria vaccine epitope has been analyzed following the booster. To better characterize the magnitude, nature, and longevity of the immune response to the booster, we measured levels of total IgM, IgG, and IgG 1-4 subclasses against three constructs of the circumsporozoite protein (CSP) and the hepatitis B surface antigen (HBsAg, also present in RTS,S) by quantitative suspension array technology in 50 subjects in the phase 3 trial in Manhiça, Mozambique. To explore the impact of vaccination on naturally acquired immune responses, we measured antibodies to P. falciparum antigens not included in RTS,S. We found increased IgG, IgG1, IgG3 and IgG4, but not IgG2 nor IgM, levels against vaccine antigens 1 month after the fourth dose. Overall, antibody responses to the booster dose were lower than the initial peak response to primary immunization and children had higher IgG and IgG1 levels than infants. Higher anti-Rh5 IgG and IgG 1-4 levels were detected after the booster dose, suggesting that RTS,S partial protection could increase some blood stage antibody responses. Our work shows that the response to the RTS,S/AS01 E booster dose is different from the primary vaccine immune response and highlights the dynamic changes in subclass antibody patterns upon the vaccine booster and with acquisition of adaptive immunity to malaria.

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Section: Discussionmentioning

confidence: 82%

Antibody responses to the RTS,S/AS01E vaccine and Plasmodium falciparum antigens after a booster dose within the phase 3 trial in Mozambique

et al. 2020

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“…This could be even more difficult for those residing in rural areas with lower healthcare access and where malaria incidence is often higher. In addition to Olotu et al, other groups have noted the phenomenon of "rebound malaria" [4,16]. Tinto et al observed a negative efficacy point estimate in the last three of 7 years of follow-up in Nanoro, Burkina Faso for both the three-and four-dose vaccines and in Kombewa, Kenya for the three-dose vaccine only.…”

Section: Discussionmentioning

confidence: 98%

“…A trend has been noted: Olotu et al showed that the vaccine tended to have a higher initial efficacy in higher transmission intensity areas, but that the efficacy waned quicker, in an extended phase II trial [3]. Tinto et al observed negative efficacy point estimates in the last three of seven years of the phase III trial in Nanoro, Burkina Faso and Kombewa, Kenya, but not in the site with the lowest incidence of malaria: Korogwe, Kenya [4]. Both Olotu et al and Tinto et al suggest that the efficacy of the vaccine, in higher transmission intensity areas, could wane to less than 0.…”

Section: Introductionmentioning

confidence: 99%

Environmental modifiers of RTS,S/AS01 malaria vaccine efficacy in Lilongwe, Malawi

et al. 2020

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Background: RTS,S/AS01 is the first vaccine against malaria to undergo pilot implementation, beginning in 2019 and vaccinating 360,000 children per year in Malawi, Ghana, and Kenya. The four-dose vaccine is given as a primary three-dose series with a fourth dose given approximately 18 months later. The efficacy of RTS,S/AS01 was variable among the 11 sites participating in the 2009-2014 phase III trial (MALARIA-055, NCT00866619), possibly due to differences in transmission intensity. However, a within-site examination of environmental factors related to transmission intensity and their impact on vaccine efficacy has yet to be conducted. Methods: We implemented the phase III RTS,S/AS01 trial at the Malawi site, which enrolled 1578 infants (6-12 weeks) and children (5-17 months) living in the Lilongwe District in Central Malawi and followed them for 3 years between 2009 and 2014. A global positioning system survey and an ecological questionnaire were conducted to collect participant household locations and characteristics, while additional data on background malaria prevalence were obtained from a concurrent Malaria Transmission Intensity (MTI) survey. Negative binomial regression models were used to assess whether the efficacy of the vaccine varied by estimated background malaria prevalence, household roof type, or amount of nearby vegetation. Results: Vaccine efficacy did not significantly vary by estimated malaria prevalence or by roof type. However, increased vegetation cover was associated with an increase in the efficacy of the three-dose primary RTS,S/AS01 series in the 18 months before the fourth dose and a decrease in the efficacy of the primary vaccine series in the second 18 months following, if the fourth dose was not given. Vegetation cover did not alter the efficacy of the fourth dose in a statistically or practically significant manner. Conclusions: Vegetation coverage in this study site might be a proxy for nearness to rivers or branching, shallow wetlands called "dambos" which could serve as breeding sites for mosquitoes. We observed statistically significant modification of the efficacy of RTS,S/AS01 by forest cover, suggesting that initial vaccine efficacy and the importance of the fourth dose varies based on ecological context. Trial registration: Efficacy of GSK Biologicals' Candidate Malaria Vaccine (257049) Against Malaria Disease Caused by P. falciparum Infection in Infants and Children in Africa. NCT00866619 prospectively registered

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“…The fourth dose of RTS,S/AS01 was more reactogenic, having more systemic and local AE during the 7 days following vaccination compared to the group which received just three doses [58,78]. Severe malaria incidence became reduced following vaccination with 50 µg RTS,S/AS01 in 3-year-old children in Tanzania, Kenya and Burkina Faso during 7-year follow-up, regardless of immunization scheme [82].…”

Section: Rtssmentioning

confidence: 92%

Plasmodium falciparum pre-erythrocytic stage vaccine development

Molina-Franky

Cuy-Chaparro

Camargo

et al. 2020

Malar J

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Worldwide strategies between 2010 and 2017 aimed at controlling malarial parasites (mainly Plasmodium falciparum) led to a reduction of just 18% regarding disease incidence rates. Many biologically-derived anti-malarial vaccine candidates have been developed to date; this has involved using many experimental animals, an immense amount of work and the investment of millions of dollars. This review provides an overview of the current state and the main results of clinical trials for sporozoite-targeting vaccines (i.e. the parasite stage infecting the liver) carried out by research groups in areas having variable malaria transmission rates. However, none has led to promising results regarding the effective control of the disease, thereby making it necessary to complement such efforts at finding/introducing new vaccine candidates by adopting a multi-epitope, multi-stage approach, based on minimal subunits of the main sporozoite proteins involved in the invasion of the liver.

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Long-term incidence of severe malaria following RTS,S/AS01 vaccination in children and infants in Africa: an open-label 3-year extension study of a phase 3 randomised controlled trial

Cited by 51 publications

References 10 publications

Antibody responses to the RTS,S/AS01E vaccine and Plasmodium falciparum antigens after a booster dose within the phase 3 trial in Mozambique

Antibody responses to the RTS,S/AS01E vaccine and Plasmodium falciparum antigens after a booster dose within the phase 3 trial in Mozambique

Environmental modifiers of RTS,S/AS01 malaria vaccine efficacy in Lilongwe, Malawi

Plasmodium falciparum pre-erythrocytic stage vaccine development

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