Public health experts are encouraging parents to get boosters for young children after concerns were raised about a low up-take at some surgeries.
The vaccine is given to children under five
Health leaders say too few youngsters are receiving the Hib vaccine, which could prevent serious illness.
The Hib (haemophilias influenza B) vaccine fights a type of flu which can cause meningitis, pneumonia or septicaemia.
A vaccine was introduced in 1992 that virtually wiped out the bug, but it is making a comeback.
Now parents of under-fours in the East Midlands are being urged to have their children vaccinated again.
The Nottingham Public Health Protection Service says the jabs often work better as children get older because their immune systems are more fully developed.
Dr Richard Slack, a communicable disease expert with the service, said: "We had good reaction to the campaign when it first started years ago, but we need to get the message across again."
"We would urge all mothers of infants to come forward when they get a letter from the NHS or their general practice."
Parents with young children are being advised to contact their GP or NHS Direct if they are in any doubt.
Children under five years old usually do not need the vaccine.