Authorities in the Philippines have ordered an investigation of a vaccine for dengue fever, that has been used on more than 730-thousand children.This comes after an announcement by French drug company, Sanofi, that said the drug could worsen the disease in some cases. A non-governmental organization in the Philippines said it had received information, that three children who were vaccinated with Dengvaxia in April 2016, had die. However, Sanofi says no deaths have been reported as a result of the programme. A spokesman for Philippines President Rodrigo Duterte said on Sunday, the government would hold to account those responsible for a programme, that had placed thousands of lives at risk.