Rotavirus vaccine
A rotavirus vaccine protects children from rotaviruses, which are the leading cause of severe diarrhoea among infants and young children.[1] Each year more than 500,000 children die from diarrhoeal disease caused by rotavirus,[2] and another two million are hospitalised.[3] Most deaths occur in developing countries, where access to treatment is limited; however, nearly every child in the world will suffer an episode of diarrhea caused by rotavirus before age five.[4]
On June 5, 2009, the World Health Organization (WHO) recommended that rotavirus vaccine be included in all national immunization programs. Clinical trials “in high-mortality, low-socioeconomic settings of South Africa and Malawi,” WHO stated, “found that the vaccine significantly reduced severe diarrhoea episodes due to rotavirus.” This announcement pertains to GlaxoSmithKline’s oral RotarixTM vaccine. Results of clinical trials with Merck’s oral RotaTeq vaccine in poorer communities in Bangladesh, Viet Nam, Ghana, Mali, and Kenya are expected in fall of 2009.[5][6]
The Rotavirus Vaccine Program aims to reduce child morbidity and mortality from diarrhoeal disease by accelerating the availability of rotavirus vaccines in developing countries. The Rotavirus Vaccine Program is a collaboration between PATH, WHO, and the U.S. Centers for Disease Control and Prevention, and is funded by the Global Alliance for Vaccines and Immunization.[7]
History
In 1998 a rotavirus vaccine (RotaShield, by Wyeth) was licensed for use in the United States. Clinical trials in the United States, Finland, and Venezuela had found it to be 80 to 100% effective at preventing severe diarrhea caused by rotavirus A, and researchers had detected no statistically significant serious adverse effects. The manufacturer of the vaccine, however, withdrew it from the market in 1999, after it was discovered that the vaccine may have contributed to an increased risk for intussusception, or bowel obstruction, in one of every 12,000 vaccinated infants. The experience provoked debate about the relative risks and benefits of a rotavirus vaccine.[8]
In 2006, two vaccines against Rotavirus A infection were shown to be safe and effective in children: Rotarix by GlaxoSmithKline[9] and RotaTeq by Merck.[10] Both are taken orally and contain disabled live virus.
Rotarix
Rotarix is a human, live attenuated rotavirus vaccine containing a rotavirus strain of G1P[8] specificity. ROTARIX is indicated for the prevention of rotavirus gastroenteritis caused by G1 and non-G1 types (G3, G4, and G9) when administered as a 2-dose series in infants and children.[9] The licensure of Rotarix is in process in the European Union.[11]
RotaTeq
RotaTeq is a live, oral pentavalent vaccine that contains five rotaviruses produced by reassortment. The rotavirus A parent strains of the reassortants were isolated from human and bovine hosts. Four reassortant rotaviruses express one of the outer capsid, VP7, proteins (serotypes G1, G2, G3, or G4) from the human rotavirus parent strain and the attachment protein VP4 (type P7) from the bovine rotavirus parent strain. The fifth reassortant virus expresses the attachment protein VP4, (type P1A), from the human rotavirus parent strain and the outer capsid protein VP7 (serotype G6) from the bovine rotavirus parent strain. In February 2006, the U.S. Food and Drug Administration approved RotaTeq for use in the United States. In August 2006, Health Canada approved RotaTeq for use in Canada.[12] Merck is working with a range of partners including the Rotavirus Vaccine Program, PATH, (Program for Appropriate Technology in Health) and other governmental and non-governmental organisations to develop and implement mechanisms for providing access to this vaccine in the developing world.[13