Covid-19 Vaccination: Manmohan Singh said the centre should retain only 10 per cent of vaccines (File) New Delhi: Veteran Congress leader Manmohan Singh has urged Prime Minister Narendra Modi to allow states to define categories of frontline workers that need to be vaccinated against Covid on priority "even if they are below 45 years of age". Asking the centre to place "enough" vaccine orders in advance, Mr Singh, in a letter, said the distribution of jabs among states should be based on a "transparent formula". "States should be given some flexibility to define categories of frontline workers who can be vaccinated even if they are below 45 years of age. For example, states may want to designate schoolteachers, bus, three-wheeler and taxi drivers, municipal and panchayat staff, and possibly lawyers who have to attend Courts as frontline workers. They can then be vaccinated even if they are below 45," he said in the letter.