As expected, US regulators have given the green light to GlaxoSmithKline’s rotavirus vaccine Rotarix, a move which will see the jab go up against Merck & Co’s rival product Rotateq.

The US Food and Drug Administration has approved Rotarix for the prevention of rotavirus gastroenteritis in infants. The agency’s decision comes after its Vaccines and Related Biological Products Advisory Committee recommended approval at the end of February and Jesse Goodman, director of the FDA's Centre for Biologics Evaluation and Research said that "This vaccine provides another option to combat and reduce a potentially severe illness that affects so many children".

Rotavirus infects virtually every child worldwide by the age of five and is the leading cause of severe gastroenteritis in infants, GSK noted. In the USA each year, 2.7 million children younger than five years of age suffer from rotavirus disease, 55,000-70,000 children are hospitalised and 20-60 die.

The approval followed a review of 11 clinical trials, involving over 75,000 children, of Rotarix which showed that the vaccine did not increase the risk of intussusception. The latter condition, which involves a twisting of the bowel, led to the recall of an earlier rotavirus vaccine, Wyeth’s Rotamune/RotaShield in 1999.

High rates of convulsion and pneumonia-related deaths were seen in some Rotarix patients in one out of the 11 studies carried out but the FDA concluded that “the available data do not establish that these events are related to the vaccine”. However, the agency has asked GSK to conduct post-marketing safety studies involving more than 40,000 infants to provide additional safety information.

GSK says that Rotarix, which is already approved in over 100 countries, allows for completion of the rotavirus vaccination series by four months of age, rather than the present six-month recommendation, as it only requires two doses. 20% of children under five who are hospitalised for rotavirus symptoms are younger than six months.

All this should help the jab make up ground in the USA on Merck’s Rotateq, which requires a three-dose course, though the latter firm believes that its vaccine is easier to administer. Rotarix brought in $182 million into GSK’s coffers last year and the US launch, scheduled for the second half of 2008, can only push that figure up, though it has much to do reach Rotateq. 2007 revenues from the latter reached $525 million.

Rotarix benefits Latin American infants
As the approval was being announced, data from a late-stage study was published in The Lancet which revealed that Rotarix is effective against severe gastroenteritis for up to two years when given to infants during their first two years.

Researchers from the Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, conducted a Phase III trial on more than 15,000 healthy infants from ten Latin American countries, who were randomly assigned to receive two oral doses of Rotarix or placebo. Out of 7,025 vaccinated infants, 32 developed gastroenteritis, compared with 161 in the 7,081 who received placebo.

The results are significant given that rotavirus causes 15,000 deaths a year in Latin America, as opposed to the 30-60 mentioned above in the USA and 200 in Europe.