Several major drugs companies have announced big cuts to the amounts they charge for their vaccines in the developing world.GSK, Merck, Johnson & Johnson and Sanofi-Aventis have agreed to cut prices through the international vaccine alliance Gavi.GSK said it would cut the price of its vaccine for rotavirus by 67% to $2.50 (£1.50) a dose in developing countries.Rotavirus-related diarrhoea kills more than 500,000 children a year.Source: BBC