As a particularly nasty strain of flu works its way around the world, some health officials say employers should pay for the cost of vaccinations.

Tackling just five health factors could prevent millions of premature deaths and increase global life expectancy by almost five years, the UN's World Health Organisation says.

Poor childhood nutrition, unsafe sex, alcohol, bad sanitation and hygiene, and high blood pressure are to blame for around a quarter of the 60 million premature deaths around the world each year, the Global Health Risks report says.