Antivirals should be given to pregnant women and young children as early as possible to prevent severe H1N1 influenza, the World Health Organization (WHO) said.

WHO clinical expert Niki Shindo said new guidelines would be issued in countries where the pandemic was spreading, according to AFP.

“Firstly, people in at-risk groups need to be treated with antivirals as soon as possible when they have flu symptoms; this includes pregnant women, children under two years old, and people with underlying conditions,” Shindo said.

Shindo said the virus had not mutated and that antiviral drugs, such as Roche‘s oseltamivir, have been shown to be safe in the most vulnerable groups of patients.