Since the neighbouring countries are still not polio-free, India needs to remain vigilant and continue with its vaccination programme against the disease, Union Health Minister Mansukh Mandaviya said on Saturday, highlighting that door-to-door inoculation campaigns will be conducted to ensure that no one is left behind. The minister, who launched the National Polio Immunisation Drive for 2022 by administering polio drops to children below five years of age in the Ministry of Health, said over 15 crore children aged below five years will be vaccinated against the disease in the coming months.