The parents of a toddler whose death prompted hundreds of thousands of people to back a campaign calling for greater coverage of the meningitis B vaccine will give evidence to MPs today.
At the moment the vaccine is only routinely available to infants and those deemed to be at risk in the UK.
The government say that offering it to every child would not be a good use of limited NHS resources.
But over 800,000 people have signed a petition calling for the immunisation effort to be expanded.
The man behind the petition, Lee Booth, 44, said it would be more cost-effective for the NHS to vaccinate all children up to at least the age of 11 rather than treating meningitis survivors for the rest of their lives.
Ahead of the first of two public evidence sessions in Parliament starting on Tuesday, father-of-two Mr Booth said ministers should consider the cost implications of not vaccinating all children.
British Gas worker Mr Booth, who lives in Newcastle-upon-Tyne, said:
Mr Booth launched the petition last September after one of his two young daughters was deemed too old to have the vaccine on the NHS.
The campaign attracted around 900 signatures until two-year-old Faye Burdett, from Maidstone, Kent, caught the infection and died on Valentine's Day after an 11-day battle.
A flood of support followed after a harrowing picture of Faye covered in a rash and lying in a hospital bed just before she died was shared by her family.
A vaccine to protect against meningitis B is available on the NHS for babies aged two months, followed by a second dose at four months and a booster at 12 months.
But parents who wish to have older children vaccinated must pay privately, although a worldwide shortage of the vaccine Bexsero means stocks are very low.
Manufacturer GlaxoSmithKline hopes to have increased stocks in the UK by the summer. The NHS programme is unaffected.