The fact that fully vaccinated children contracted a potentially fatal disease is the latest in a number of disturbing revelations to undermine public confidence.These include news that thousands of children will have to be re-inoculated against TB as the vaccines they received were not potent enough, and that uptake of the controversial MMR vaccine has fallen to unsafe levels because parents are worried about a possible link with autism.In addition, a damning report first revealed in Ireland On Sunday, hints that vaccines may not always be kept properly refrigerated and are sometimes used after their expiry date.

This latest revelation regarding the children with whooping cough will cause yet more heart-searching for parents. The disease causes coughing so violent that children have to 'whoop' to inhale and it can lead to fatal complications like pneumonia, brain swelling or brain haemorrhage. The children have not been named, but we can reveal that they live in the Southeast. Public health specialist Dr Neville de Souza of the South Eastern Health Board said the cases were unrelated to each other and that a small percentage of children contracting whooping cough after full immunisation is known to happen.

To most people, whooping cough is an illness from another era but it has never gone away. In a separate incident, two Irish children died from the disease last year.Statistics from the National Disease Surveillance Centre (NDSC) show that countrywide, recorded cases have been falling since the mid-1990s, but the story is very different in the Southeast, where cases have been rising in the past three years.In the year 2000, the South Eastern Health Board's figure was 11, but that has increased to 26 so far this year. And as only those who are taken to hospital are usually recorded, it is believed the true figures may be 10 times higher.

'The whooping cough vaccine is not one of the most effective vaccines and doesn't take in a percentage of children,' Dr de Souza said. 'The immunity doesn't last. While there will be a small percentage of children who do get the whooping cough after being fully immunised, it wouldn't be as severe as it is in unimmunised children and the children don't tend to carry the virus.'Dr Lorraine Hickey of the NDSC said: 'There is no such thing as a 100pc effective vaccine but the vaccines are generally very effective.'The wider issue of immunisation against TB and other major diseases continues to cause alarm, however.

Health Minister Micheál Martin last month set up an expert group to investigate vaccines after the Irish Medicines Board, which regulates drugs, withdrew a batch of BCG, which is given to babies to protect against TB. It was said the vaccines were not potent enough and that more than 2,500 children would have to be re-inoculated. Meanwhile, parents' fears have not been allayed by assurances that the MMR vaccine - given to protect against measles, mumps and rubella - is not linked to autism, and national uptake of the vaccine has dropped to just over 70pc. For the MMR programme to succeed, an uptake level of 95pc is required.It has also emerged that a large number of out-of-date polio vaccines were distributed in the late 1990s, forcing re-inoculation of thousands.

This picture of a shambolic vaccination programme is outlined in a confidential report conducted by the health boards and revealed by Ireland on Sunday earlier this year. A main recommendation in the report was the setting up of a new body to oversee the vaccination programme. Health Minister Martin has not, however, made any moves to establish the new body. Patients' Association spokesman Stephen McMahon said: 'Immunisation programmes are a crucial element for any society. The management, production, distribution and delivery must be well managed for everyone to have confidence in the programmes.'