Bristol nine-year-old Solly Foster is like any other girl this Christmas, playing with her brother and sister and excited about what presents she might get.

It is a welcome change for the girl the Foster family, from Montpelier, celebrated Christmas with last year.

Solly spent the day needing intravenous drugs every eight hours to fight off a life-threatening infection.

Three years ago Solly was diagnosed with Common Variable Immunodeficiency (CVID), which means she does not have the defensive cells that help fight infections.

She spent much of 2007 in Bristol Children's Hospital with infections and bouts of pneumonia, and in the lead up to Christmas she was in hospital again, coughing and feverish.

Doctors believe she developed a particularly resistant infection which may have caused all her illnesses.

Solly's mother, Tot, 40, said: "They confirmed that she definitely had that infection on December 21, and then put her on heavy duty antibiotics.

"It was my mum's 70th birthday on Christmas Eve and we really wanted her to be able to get out of hospital for that.

"The Children's Hospital staff did everything they could to get her home."

Staff trained Solly's father, IT engineer Dan Tagg, 42, to make up Solly's intravenous drugs and give them to her.

Tot's cousin, an adult nurse, also received training so she could help out.

Solly was out of hospital on Christmas Eve, but still needed intravenous drugs every eight hours.

"It was a difficult time, and Solly says it makes her sad to think back to it. She is relieved that she is not ill like that now – and she is really looking forward to Christmas this year," said Tot, a former university lecturer.

This year has been better for Solly, who has not been in hospital since January.

In July her doctors said the infection to blame for her Christmas illness had finally been killed off.

But it was only one battle out of many Solly has fought and will have to fight.

"It is always breathing down your neck, the unpredictability of it all," said Tot.

"We know she will have to go back into hospital at some point."

But Tot is full of praise for the help the family gets from the Children's Hospital, and their support from the charity WellChild.

"I cannot praise the hospital staff enough," she said.

"They are so understanding of what Solly needs as a little girl. They know she needs to have as normal life as possible – they do anything they can to keep her out of hospital and with us at home."

WellChild, which supports ill children and their families, helps to fund Bath-based service Lifetime, which provides a nurse who makes it easier for the family to get on with day to day life by doing tasks such as replenishing the supply of syringes needed to give Solly her medication.

Lifetime also provides a psychologist to help Solly with her fears and anxieties.

Solly does physiotherapy exercises every day for her lungs, takes antibiotics daily and has an infusion of immunoglobulin – the infection-fighting cells which she lacks – once a week, but when she is well her parents try to make her life as normal as possible.

There is more information on WellChild available at www.wellchild.org.uk.