A toddler almost died from meningitis when Ealing Hospital staff sent her home after initially misdiagnosing her as having a harmless temperature.
Erin Kent was saved only when parents Lisa and Andy Kent insisted on bringing her back to the hospital later that day.
Now Mr and Mrs Kent have pledged to help find a vaccine by participating in a sponsored walk for charity Meningitis UK.
Erin suffered meningitis last December when she was seven months old.
When Mrs Kent, of Beechwood Avenue, Greenford, took her daughter to the hospital with a temperature she was told to take the child home and give her Calpol.
The 32-year-old mother said: "As the day went on I still felt something was wrong. My mum always told me to go with my instincts, so when Erin began vomiting I took her back to hospital.
"By the time we got there she was having fits and her temperature was 42 degrees. They didn't know what was wrong but the doctor gave her a massive antibiotics dose just in case."
That dose saved Erin's life as a lumber puncture confirmed she had meningococcal meningitis. Doctors told her that had Mrs Kent left it another few hours Erin would have died.
The disease left her immune system weakened and has affected her brain, meaning she does not now know when she is hungry.
Mrs Kent added: "We don't know the full impact meningitis will have. She still suffers fits; we've been lucky - she could easily have been in a box."
Mr and Mrs Kent raised £2,000 and are walking the last leg of the char-ity's Big 4 Walk with other families affected by meningitis.
Meningitis UK founder Steve Dayman said: "Vaccine research requires a large amount of investment. With continued support we can achieve our goal."
To sponsor Mr and Mrs Kent, visit www.justgiving.com/lisa andandykent.
* For more information on Meningitis UK call 0117 373 73 73 or visit www.meningitisuk.org .