One in five children under the age of six months was not vaccinated last year, the Department of Health has revealed.

The news sparked concern among children’s health experts.

Richard Fulton, a paediatrician, said the drop should be a concern for the entire population of the island.

Dr Fulton explained: “When you think about vaccinations, most people think about vaccination to protect the individual from infection, but there’s also vaccination to protect the population.

“If you have vaccination rates below 80 per cent, you are at the stage where you are losing your herd immunity.

“Basically, if you vaccinate enough people, then you can protect the population at large, but if you drop below 80 per cent you are risking losing that.

“If there is an infection of something like measles or polio coming into the country and you have enough people who are not vaccinated, it means that it will spread easier and affect a much larger portion of the population.”

Dr Fulton spoke out after a Department of Health spokesman said vaccine coverage for infants up to six months of age fell from 94 per cent to 79 per cent in 2017. But the spokesman added the decline may not just be due to parental refusal to vaccinate their children.

The spokesman said: “While the Department of Health is concerned, the change may be a result of a combination of factors. Parents delaying their child’s vaccination, persons declining vaccines altogether for themselves and their family or changes in health-seeking behaviour as the risk of the diseases are perceived to be low.

“The Department of Health also can’t rule out that some children expected to be vaccinated may have left the island.”

Dr Fulton said there was a trend where parents delayed or refused vaccinations for their children.

He added that some parents were worried children were given too many vaccines too young.But he emphasised there was no scientific evidence to support that view.

Dr Fulton said: “I often get parents who come in and say they have done their research.

“As someone who has spent the better part of their adult life studying vaccinations and having these conversations about vaccinations three or four times a day, it’s a little galling.

“It’s difficult because as a parent you can find all this information.

“You can find reams and reams of information by pseudo-scientists and people who sound like they know what they are talking about and there’s nothing to back up what they say.”

He said the situation was worsened because younger generations do not have the same kind of experience of potential killer diseases that their parents had. Dr Fulton said: “My background is working in intensive care in the UK.

“People often say to me they don’t want to get their child vaccinated against chickenpox, but when I was in the UK I looked after two children who died because of chickenpox. I have treated children with tetanus. I have seen children die of measles.

“I think this generation has been immunised against immunisation because they don’t know people who died of these infections. The other issue is social media and a lot of fake news around this topic.”

Lynn Jackson, child health co-ordinator at the Department of Health, said the decline affected the entire community.

She said: “When more people choose not to vaccinate the risk of getting the disease is greater, especially for the most vulnerable — infants and the elderly.

“But when 95 per cent of all children receive the vaccines as recommended it will help protect those who can’t be vaccinated or who are too young to be vaccinated. The practice of delaying vaccination for infants and young children merely delays their protection from the disease.”

Ms Jackson added reputable scientific evidence underlined the importance and safety of vaccination. She said: “The safety and effectiveness of vaccines are under constant study. Because vaccines are designed to be given routinely to children, they must be extraordinarily safe.

“Safety testing begins as soon as a new vaccine is contemplated, continues until it is licensed, and is monitored indefinitely after being licensed.”