A significant number of infants missed out on essential vaccinations. Infants who have not received a specific vaccine by age one are considered zero-dose children. This vaccine is crucial as it contains protection against diseases such as diphtheria and pertussis.

Further information is available from the source, which reports on the situation in multiple countries. The source provides details on the definition of zero-dose children and the number of children affected.

A total of 57 countries are involved, with a substantial number of children having received no routine vaccine, according to the available data.