Research results show need to tailor vaccines to improve their impact
Nov 11, 2012
Rotavirus is an important cause of life-threatening diarrhoea in Africa but available vaccines may not be the best adapted. Research presented at the 7th African Rotavirus Symposium by Epicentre, the epidemiological research arm of Médecins Sans Frontières (MSF) and other African researchers contributes to this growing body of evidence.
“Vaccine developers have not taken into account the full rotavirus picture in places that are hardest hit by diarrheal illness and deaths caused by rotavirus,” said Dr Anne-Laure Page, an epidemiologist at Epicentre. “This study adds to the growing body of research that underscores the need to ensure that vaccines are developed that effectively address the needs of developing countries.”
The research includes two years of surveillance data of over 10,000 children with severe diarrhoea in Niger. Stool samples were collected from all children under 5 years having diarrhoea with moderate or severe dehydration and tested for rotavirus using a rapid diagnostic test. The data confirms that rotavirus is an important cause of severe diarrhoea in Africa; 30.4% of the cases in the study were associated with rotavirus. However, the most common rotavirus genotypes documented in the study are not included in the two existing vaccines that aim to prevent the disease (GSK’s Rotarix and Merck’s RotaTeq).
The two available rotavirus vaccines were developed and tested in industrialised countries, and have an efficacy rate of 90% against severe diarrhoea in these countries, compared to an estimated 50-60% in countries in Africa and Asia. The current vaccines are also bulky and have a limited shelf life at room temperature, further making them unsuitable for developing countries that lack adequate refrigeration capacity.
“Right now, vaccines are mainly developed for industrialised countries and then used in Africa and Asia at a later stage, whether they’re adapted to those contexts or not,” said Kate ELDER, Vaccines Policy Advisor with MSF’s Access Campaign. “We need to see a paradigm shift in vaccine development, with the specific needs of developing countries incorporated into research and development from the very start of the process.”
Epicentre’s research further builds the case that global immunisation effort needs to prioritise better-adapted vaccines for developing countries and settings where MSF operates.
A study in Uganda is looking to address the burden of pneumococcal disease in vulnerable populations by delivering one dose of pneumococcal conjugate vaccine (PCV) to a wide age range, instead of a three-dose schedule to young children. There is presently no WHO recommendation or global policy on the use of PCV in crisis-affected populations. The results of this research may have applications for routine programmes, in addition to interventions in crises.
Another Epicentre study in Chad is looking at use of the tetanus toxoid vaccine in a flexible cold chain, because keeping vaccines cold represents a major logistical obstacle to vaccinating children in many remote and rural settings.
“The fact that currently available vaccines are not easy to use in the places that are hardest to reach contributes to the fact that 22 million children born each year do not receive even the basic vaccination package,” said Elder.
“Vaccine developers have not taken into account the full rotavirus picture in places that are hardest hit by diarrheal illness and deaths caused by rotavirus,” said Dr Anne-Laure Page, an epidemiologist at Epicentre. “This study adds to the growing body of research that underscores the need to ensure that vaccines are developed that effectively address the needs of developing countries.”
The research includes two years of surveillance data of over 10,000 children with severe diarrhoea in Niger. Stool samples were collected from all children under 5 years having diarrhoea with moderate or severe dehydration and tested for rotavirus using a rapid diagnostic test. The data confirms that rotavirus is an important cause of severe diarrhoea in Africa; 30.4% of the cases in the study were associated with rotavirus. However, the most common rotavirus genotypes documented in the study are not included in the two existing vaccines that aim to prevent the disease (GSK’s Rotarix and Merck’s RotaTeq).
The two available rotavirus vaccines were developed and tested in industrialised countries, and have an efficacy rate of 90% against severe diarrhoea in these countries, compared to an estimated 50-60% in countries in Africa and Asia. The current vaccines are also bulky and have a limited shelf life at room temperature, further making them unsuitable for developing countries that lack adequate refrigeration capacity.
“Right now, vaccines are mainly developed for industrialised countries and then used in Africa and Asia at a later stage, whether they’re adapted to those contexts or not,” said Kate ELDER, Vaccines Policy Advisor with MSF’s Access Campaign. “We need to see a paradigm shift in vaccine development, with the specific needs of developing countries incorporated into research and development from the very start of the process.”
Epicentre’s research further builds the case that global immunisation effort needs to prioritise better-adapted vaccines for developing countries and settings where MSF operates.
A study in Uganda is looking to address the burden of pneumococcal disease in vulnerable populations by delivering one dose of pneumococcal conjugate vaccine (PCV) to a wide age range, instead of a three-dose schedule to young children. There is presently no WHO recommendation or global policy on the use of PCV in crisis-affected populations. The results of this research may have applications for routine programmes, in addition to interventions in crises.
Another Epicentre study in Chad is looking at use of the tetanus toxoid vaccine in a flexible cold chain, because keeping vaccines cold represents a major logistical obstacle to vaccinating children in many remote and rural settings.
“The fact that currently available vaccines are not easy to use in the places that are hardest to reach contributes to the fact that 22 million children born each year do not receive even the basic vaccination package,” said Elder.
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