LIKE many parents, Gary and Kerry-Anne Baxter did not think a case of the flu was that serious — until it almost killed their four-year-old daughter.

“They said we needed to say goodbye, she might not survive. We were in shock and devastated. It didn’t dawn on me flu could be so serious,” Mrs Baxter said.

When their twins were diagnosed with the flu, Ellie began to improve after six days of a high fever and coughing. But her identical twin Rosie developed pneumonia, a common complication of influenza, and ended up on life support.

“She was in a coma for 10 days and twice we were told she probably wouldn’t live. The doctors told us she was the most critically ill child in the state at one point,” Mrs Baxter said.

After a 10-day bedside vigil, Rosie finally turned the corner. Weighing 24kg before, she lost a quarter of her body weight, but miraculously pulled through.

“It was extremely traumatic. We had no idea this is what flu could do, we didn’t know it still killed people and the doctors said it can happen to any healthy child, it doesn’t discriminate,” she said.

Now eight, Rosie is shorter than her identical twin sister, a legacy of the illness’s impact on her body.

Influenza is the 11th-most common cause of death, claiming on average 3000 lives a year. It kills more children than meningococcal disease and the only prevention is vaccination.

“I vaccinate the family every year. People underestimate these diseases and I’m delighted NSW has agreed to offer a free flu vaccination to children,” Mrs Baxter said.

Dr Vicky Sheppeard, NSW Health’s director communicable diseases, said NSW experienced one of the worst flu seasons on record last year with more than 650 deaths, including two children.

She said this year’s flu shot will be available from tomorrow at most GPs, Aboriginal Medical Services and council and community health clinics that routinely provide vaccination services.

Children up to five years of age will be eligible for free flu shots this year. Children are more vulnerable to influenza as their immune systems have not been exposed before.

“Less than 5 per cent of children were vaccinated and last year there were 12,500 notifications of children hospitalised and two children died,” Dr Sheppeard said.

Sydney University’s Immunisation expert Professor Robert Booy said siblings like Rosie often get sicker as a result of a heavier exposure to the virus.

“The first twin perhaps got a small infecting dose at daycare, but the second twin, or sibling in other families, get a heavier dose due to more exposure. The second sibling tends to get flu more severely,” Prof Booy said.

Last year in Australia there were 221,853 flu infections, one of the worst on record.

Influenza A H3N2 was responsible for the majority of deaths in the elderly and influenza B mostly responsible for illness in children.

Only 23 per cent were vaccinated and the H3N2 virus mutated during the vaccine production, rendering the vaccine less effective.

Dr Sheppeard said NSW Health has made the flu vaccine mandatory for staff who work in Intensive Care Units and cancer, transplant, neonatal and birth and labour wards in the state’s public health facilities.