Merck & Co will be hoping to enjoy some welcome relief from news coverage of its Vioxx drug liability lawsuits when one of its new vaccine products, Rotateq, goes up against a US Food and Drug Administration (FDA) advisory committee later today.

But statements published by the FDA reviewer in the application ahead of the meeting suggest that a positive vote may not be a foregone conclusion. The FDA is of the opinion that Rotateq is safe for the prevention of rotavirus diarrhoea in children, but may need additional evidence to support its efficacy.

One study is supportive of efficacy, according to statements posted on the FDA website, but questions still remain about a second, confirmatory trial. However, the concerns seem to relate to a discrepancy in the way the efficacy data has been presented in the dossier, rather than any failure of the vaccine, and the FDA reviewer maintains that Rotateq seems to be ‘highly effective’.

Crucially, the FDA report notes that there is no evidence that Rotateq causes the sometimes fatal intestinal twisting (intussusception) cases that caused Wyeth to withdraw its rotavirus vaccine RotaShield in 1999. It is expected that the panel will ask Merck to undertake stringent monitoring of this potential side effect if the product reaches the market.

Rotavirus is a serious pathogen, killing nearly 500,000 children under age five every year worldwide. In the USA, the virus causes about 50,000 hospitalisations and 20 to 40 deaths a year. Merck said earlier this month it had started a major clinical development programme for the vaccine in Asia.

Merck and European partner for Rotateq, Sanofi Pasteur MSD, are going head-to-head with GlaxoSmithKline in the race to bring rotavirus vaccination back to world markets. GSK’s Rotarix product candidate has already been launched in Mexico, its first market, but has not yet been filed for approval in the USA.