Hertfordshire health officials are urging pregnant women to ensure they are vaccinated against whooping cough to protect their newborn babies – as the number of cases increases across the UK.

Nationwide, 4,793 cases were confirmed between January and April this year – compared to just 858 in the whole of 2023.

During the same period in Hertfordshire there have been 124 cases, which is said to be “far higher” than normal.

Babies under three months are at the highest risk of developing complications from whooping cough, which is also known as petassis. So far this year eight babies have died nationwide – although no deaths have been recorded in Hertfordshire.

Newborns are offered a vaccination against the bacterial infection from the age of eight weeks.

But until then they rely on antibodies passed on from their mothers, in response to a maternal vaccination that can be administered after the 20-week stage of the pregnancy.

In Hertfordshire and West Essex, latest data suggests that just 65 per cent of new mums have been vaccinated during pregnancy – compared to a target of 95 per cent.

Hertfordshire’s director of public health Sarah Perman acknowledged that some women may be worried about having a vaccination during their pregnancy.

But speaking at a media briefing on Monday (June 17), she said the vaccine had been used for many years, was “totally safe” and was the best possible thing mums to be could do to protect their infants.

“When the whooping cough vaccination is given in pregnancy it helps women to produce antibodies to protect against whooping cough,” she said.

“These antibodies are then passed on to the baby, through the placenta – giving the baby high levels of protection until they are able to have their own whooping cough vaccination, from the age of eight weeks.”

Ms Perman describes the deaths of the eight babies already recorded as  “really, really shocking”.

“We do need to do everything we can to make sure the message is out there – and try to make sure we don’t have any further seriously ill or even babies that die because of petassis.”

Ms Perman stresses that any woman who is concerned about the vaccination or who may not have been offered it after 20-weeks of their pregnancy can talk to their midwife or GP.

Whooping cough is a bacterial infection of the lungs and airways. It initially has symptoms that are similar to a cold, such as a runny nose and a sore throat.

But after a week it will lead to coughing bouts that can last for a few minutes – and may make a characteristic ‘whoop’ sound, made by the gasp of air between coughs.

It can be spread very easily through coughing and sneezing, says Ms Perman.

Vaccination is routinely offered for young infants at eight, 12 and 16 weeks, as part of the ‘six in one’ vaccination – with a pre-school booster.

And in Hertfordshire Ms Perman says the routine childhood vaccination rate is 91 per cent at 12 months of age – which is still lower than the 95 per cent target.

However immunity from the vaccine does wane over time and Ms Perman says they are seeing cases in teenagers and young people who have and have not been vaccinated.