Rotavirus Vaccine Shows Promise In Latin American Infants

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Main Category: Immune System / Vaccines
Also Included In: Infectious Diseases / Bacteria / Viruses;  Public Health;  Pediatrics / Children's Health
Article Date: 04 Apr 2008 - 0:00 PST

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By administering two doses of an oral, live, attenuated human rotavirus to Latin American infants during the first two years of life, scientists were able to effectively fight severe rotavirus gastroenteritis for up to two years. These results were published in an Article released on April 4, 2008 in The Lancet.

Rotavirus is a genus of viruses storing its genetic information in double stranded RNA. Organisms in this genus are a leading cause of diarrhea in young children, and it is transmitted by oral contact with fecal matter. It is extremely common, and affects children in developed and developing countries around the world. In developing countries, however, it is a leading cause of death in infants and children, which lends great importance to the development of an effective vaccine.

To this end, Professor Miguel O'Ryan, Institute of Biomedical Sciences, Faculty of Medicine, University of
Chile, and colleagues performed a double-blind, placebo-controlled phase III study with 12,183 healthy infant subjects from ten Latin American countries. These children were randomly assigned to groups administered either two oral doses of RIX4414, the vaccine, or a placebo. The team then measured the efficacy of the vaccine from two weeks after the second dose until one year of age, during the second year, and for the entire two year period until 24 months of age.

In the analysis of the data, the vaccine showed the following:

• In the combined two year period, fewer cases of severe rotavirus gastroenteritis (0.4% or 32 of 7205) were reported in the vaccinated infants than in the placebo group (2.3% or 161 of 7081). 
• For the specific wild-type G1 rotavirus strain, the vaccine was 80.5% - 82.1% effective. Against non-G1 strains as a whole group, the efficacy was 77.5%, and of the non-G1 strains, the vaccine was 80.5% effective against P8 strains. 
• Efficacy for hospital admission for rotavirus gastroenteritis was 83.0%. Efficacy for admission for diarrhea of any kind was 39.3%. 
• Intussusception, the invagination of one part of the intestine into another, was not reported for the second year.

The researchers conclude with a discussion of the potential positive effects widespread use of this vaccine could have. "The investigators conclude: "Inclusion of this vaccine in routine paediatric immunisation schedules can be expected to greatly reduce the burden of rotavirus disease worldwide." 

Professor Keith Grimwood of the Queensland Paediatric Infectious Disease Laboratory, Discipline of Paediatrics and Child Health, Royal Children's Hospital and University of Queensland, Brisbane, Australia, contributed an accompanying article in which he gives some perspective on the instances of rotovirus and future expectations of this vaccine program. "WHO is awaiting efficacy data from low-income countries of Africa and Asia, where much greater strain diversity exists and where 413,000 rotavirus deaths occur every year compared with 15,000 in Latin America and 200 in Europe." 

Efficacy and safety of an oral live attenuated human rotavirus vaccine against rotavirus gastroenteritis during the first 2 years of life in Latin American infants: a randomised, double-blind, placebo-controlled phase III study.
Alexandre C Linhares, F Raul Velazquez, Irene Perez-Schael, Xavier Saez-Llorens, Hector Abate, Felix Espinoza, Pio Lopez, Mercedes Macias-Parra, Eduardo Ortega-Barria, Doris Maribel Rivera-Medina, Luis Rivera, Noris Pavia-Ruz, Ernesto Nunez, Silvia Damaso, Guillermo M Ruiz-Palacios, Beatrice De Vos, Miguel O'Ryan, Paul Gillard, Alain Bouckenooghe, and the Human Rotavirus Vaccine Study Group
The Lancet, Vol 371, April 5, 2008
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Human rotavirus vaccines: too early for the strain to tell
Keith Grimwood, Carl D Kirkwood
The Lancet, Vol 371, April 5, 2008
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Written by Anna Sophia McKenney
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