A mother is urging pregnant women to take advantage of a new vaccine offer after she watched “helplessly” as her newborn baby became infected with a serious virus.

Alice Cook’s daughter Henrietta became seriously ill with respiratory syncytial virus (RSV) and had to be treated in emergency hospital at the age of just three weeks.

“Henrietta’s hospital stay was so scary and I wouldn’t wish what we went through on any other family,” Ms Cook said.

The UK Health Safety Authority and the Joint Committee on Vaccination and Immunisation (JCVI) will offer the vaccine to women aged 28 weeks or older from 1 September.

RSV infects about 90% of children within the first two years of life.

The virus is one of the leading causes of child mortality worldwide, resulting in approximately 20,000 hospitalizations of children under one year of age.

It typically causes mild, cold-like symptoms that can lead to severe lung infections such as pneumonia and infant bronchiolitis.

The JCVI expects the vaccination rate to be around 60%. It is hoped that this could save 70,000 RSV infections in infants.

Ms Cook urged more mothers to get involved.

“Since there is no medication for RSV, I felt helpless and it was really a waiting game to see if she would recover,” she said.

“After nine months, Henrietta is now a happy and healthy baby, but the first few weeks of her life were incredibly tough and not what I had imagined a newborn’s bladder would be like.

“I would encourage all pregnant women to get vaccinated against RSV.”

Carmen Murillo of Bristol said she would have been vaccinated if the vaccine had been available when she was pregnant with her daughter.

“I got all my vaccinations when I was pregnant with her and I think it’s a brilliant idea,” she said.

“If that’s what my baby needs, I would just do it.”

Dr Matthew Dominey, of NHS England South West, said he understood that some mothers might have concerns, but the vaccine had been extensively tested and its safety was proven.

He said: “We hope that this vaccine will prevent a large number of hospitalisations for infants. This will free up capacity and time in hospitals to treat other infants and ensure that these sick babies do not have to suffer.”

In addition to the maternal vaccination program, people who turn 75 on or after September 1 will be offered free RSV vaccination.