Britain has become the first country to implement a vaccination program for all newborn babies against meningitis B, which is fatal in one in 10 cases.
Campaigners hope the vaccine, which will be given to babies at two, four and 12 months old, will prevent up to 4000 cases by 2025.
It is billed as the world's first nationwide publicly-funded program against the infection.
Trials found that the vaccine was effective against 88 percent of the hundreds of strains of meningococcal group B bacteria.
"Over the next decade this vaccine could potentially prevent up to 4000 cases of meningococcal disease in children younger than five years in the UK," said Christopher Head, from the Meningitis Research Foundation, on Tuesday (local time).
Sue Davie, chief executive of the charity Meningitis Now, called the move a "massive step forward".
Group B is the most common meningitis in Britain, with around 1700 cases diagnosed each year. Babies already receive a meningitis C vaccination.
The National Health Service warns that the vaccine can cause side effects, "but studies suggest they are generally mild and don't last long".
"Since the vaccine was licensed, almost a million doses have been given, with no safety concerns identified," it said.
Bacterial meningitis, which includes Meningitis B, accounts for 170,000 deaths globally every year, according to the World Health Organisation.