Offering the meningitis B vaccine to all children is "not cost effective" and would be a waste of NHS money, the UK government says.
Public support for extending the vaccine grew after the mother of two-year-old Faye Burdett shared pictures of her dying from the infection.
The jab is offered to children in their first year of life.
But more than 800,000 people signed a petition for it to be given to all children under 11.
Faye, from Maidstone, died on Valentine's Day after fighting the infection for 11 days. Her mother Jenny said the family had endured "a pain you cannot describe".
And soon after ex-England rugby captain Matt Dawson talked about how his two-year-old son Sam survived meningitis W after "two weeks of hell".
In response to the most popular petition in parliamentary history, the Department of Health said it was following the expert advice of its Joint Committee on Vaccination and Immunisation (JCVI).
It said: "With this programme, our priority is to protect those children most at risk of Men B, in line with JCVI's recommendation.
"The NHS budget is a finite resource, it is therefore essential that JCVI's recommendations are underpinned by evidence of cost-effectiveness.
"Offering the vaccine outside of JCVI's advice would not be cost effective, and would not therefore represent a good use of NHS resources which should be used to benefit the health and care of the most people possible."
It added: "When any new immunisation programme is introduced, there has to be a cut-off date to determine eligibility.
"While this is extremely difficult for parents whose children aren't eligible, there is no other way of establishing new programmes to target those at highest risk without introducing inequalities."
The UK is the only country in the world to offer the vaccine routinely to children of any age.
It is offered only in the first year of life when infants are most vulnerable to the infection.
The issue is still scheduled to be debated in the House of Commons.
Lee Booth, who set up the petition, said: "It's very disappointing that that's the initial sort of reaction to the campaign.
"Y'know there's 817-thousand people that have obviously raised concerns over the lack of the meningitis B vaccine being available, to their children.
"It beggars belief really that the government are putting costs ahead of saving childrens' lives."
Follow James on Twitter.