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Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine
BACKGROUND: A Phase 1-2b study of the blood stage malaria vaccine AMA1-C1/Alhydrogel was conducted in 336 children in Donéguébougou and Bancoumana, Mali. In the Phase 2 portion of the study (n = 300), no impact on parasite density or clinical malaria was seen; however, children who received the stud...
Autores principales: | , , , , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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BioMed Central
2011
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3036666/ https://www.ncbi.nlm.nih.gov/pubmed/21247484 http://dx.doi.org/10.1186/1475-2875-10-13 |
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author | Ellis, Ruth D Fay, Michael P Sagara, Issaka Dicko, Alassane Miura, Kazutoyo Guindo, Merepen A Guindo, Aldiouma Sissoko, Mahamadou S Doumbo, Ogobara K Diallo, Dapa |
author_facet | Ellis, Ruth D Fay, Michael P Sagara, Issaka Dicko, Alassane Miura, Kazutoyo Guindo, Merepen A Guindo, Aldiouma Sissoko, Mahamadou S Doumbo, Ogobara K Diallo, Dapa |
author_sort | Ellis, Ruth D |
collection | PubMed |
description | BACKGROUND: A Phase 1-2b study of the blood stage malaria vaccine AMA1-C1/Alhydrogel was conducted in 336 children in Donéguébougou and Bancoumana, Mali. In the Phase 2 portion of the study (n = 300), no impact on parasite density or clinical malaria was seen; however, children who received the study vaccine had a higher frequency of anaemia (defined as haemoglobin < 8.5 g/dL) compared to those who received the comparator vaccine (Hiberix). This effect was one of many tested and was not significant after adjusting for multiple comparisons. METHODS: To further investigate the possible impact of vaccination on anaemia, additional analyses were conducted including patients from the Phase 1 portion of the study and controlling for baseline haemoglobin, haemoglobin types S or C, alpha-thalassaemia, G6PD deficiency, and age. A multiplicative intensity model was used, which generalizes Cox regression to allow for multiple events. Frailty effects for each subject were used to account for correlation of multiple anaemia events within the same subject. Intensity rates were calculated with reference to calendar time instead of time after randomization in order to account for staggered enrollment and seasonal effects of malaria incidence. Associations of anaemia with anti-AMA1 antibody were further explored using a similar analysis. RESULTS: A strong effect of vaccine on the incidence of anaemia (risk ratio [AMA1-C1 to comparator (Hiberix)]= 2.01, 95% confidence interval [1.26,3.20]) was demonstrated even after adjusting for baseline haemoglobin, haemoglobinopathies, and age, and using more sophisticated statistical models. Anti-AMA1 antibody levels were not associated with this effect. CONCLUSIONS: While these additional analyses show a robust effect of vaccination on anaemia, this is an intensive exploration of secondary results and should, therefore, be interpreted with caution. Possible mechanisms of the apparent adverse effect on haemoglobin of vaccination with AMA1-C1/Alhydrogel and implications for blood stage vaccine development are discussed. The potential impact on malaria-associated anaemia should be closely evaluated in clinical trials of AMA1 and other blood stage vaccines in malaria-exposed populations. |
format | Text |
id | pubmed-3036666 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-30366662011-02-10 Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine Ellis, Ruth D Fay, Michael P Sagara, Issaka Dicko, Alassane Miura, Kazutoyo Guindo, Merepen A Guindo, Aldiouma Sissoko, Mahamadou S Doumbo, Ogobara K Diallo, Dapa Malar J Research BACKGROUND: A Phase 1-2b study of the blood stage malaria vaccine AMA1-C1/Alhydrogel was conducted in 336 children in Donéguébougou and Bancoumana, Mali. In the Phase 2 portion of the study (n = 300), no impact on parasite density or clinical malaria was seen; however, children who received the study vaccine had a higher frequency of anaemia (defined as haemoglobin < 8.5 g/dL) compared to those who received the comparator vaccine (Hiberix). This effect was one of many tested and was not significant after adjusting for multiple comparisons. METHODS: To further investigate the possible impact of vaccination on anaemia, additional analyses were conducted including patients from the Phase 1 portion of the study and controlling for baseline haemoglobin, haemoglobin types S or C, alpha-thalassaemia, G6PD deficiency, and age. A multiplicative intensity model was used, which generalizes Cox regression to allow for multiple events. Frailty effects for each subject were used to account for correlation of multiple anaemia events within the same subject. Intensity rates were calculated with reference to calendar time instead of time after randomization in order to account for staggered enrollment and seasonal effects of malaria incidence. Associations of anaemia with anti-AMA1 antibody were further explored using a similar analysis. RESULTS: A strong effect of vaccine on the incidence of anaemia (risk ratio [AMA1-C1 to comparator (Hiberix)]= 2.01, 95% confidence interval [1.26,3.20]) was demonstrated even after adjusting for baseline haemoglobin, haemoglobinopathies, and age, and using more sophisticated statistical models. Anti-AMA1 antibody levels were not associated with this effect. CONCLUSIONS: While these additional analyses show a robust effect of vaccination on anaemia, this is an intensive exploration of secondary results and should, therefore, be interpreted with caution. Possible mechanisms of the apparent adverse effect on haemoglobin of vaccination with AMA1-C1/Alhydrogel and implications for blood stage vaccine development are discussed. The potential impact on malaria-associated anaemia should be closely evaluated in clinical trials of AMA1 and other blood stage vaccines in malaria-exposed populations. BioMed Central 2011-01-19 /pmc/articles/PMC3036666/ /pubmed/21247484 http://dx.doi.org/10.1186/1475-2875-10-13 Text en Copyright ©2011 Ellis et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Ellis, Ruth D Fay, Michael P Sagara, Issaka Dicko, Alassane Miura, Kazutoyo Guindo, Merepen A Guindo, Aldiouma Sissoko, Mahamadou S Doumbo, Ogobara K Diallo, Dapa Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
title | Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
title_full | Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
title_fullStr | Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
title_full_unstemmed | Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
title_short | Anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
title_sort | anaemia in a phase 2 study of a blood stage falciparum malaria vaccine |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3036666/ https://www.ncbi.nlm.nih.gov/pubmed/21247484 http://dx.doi.org/10.1186/1475-2875-10-13 |
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