Ezra Goodjohn, from Stannington, was rushed to Sheffield Children's Hospital following a visit to an out-of-hours GP after he started feeling unwell three days after Christmas 2019.
But within hours, the 18-month-old toddler was pronounced dead, with early indications that he may have developed sepsis.
Since his tragic passing, Ezra's family have worked tirelessly to raise funds and awareness for the disease, which many still appear to be unaware of.
His mum, Emma Chadburn, told how in the two and a bit years since then, she has raised more than £2,000 while working at Morrisons in Hillsborough and £7,000 through a tribute fund set up between Just Giving and UK Sepsis Trust.
This time around, they want to 'throw a big party' in August for Ezra, who would have been four in July, to raise funds for the charity after being unable to do so the previous two years owing to lockdown.
Family ‘trying to keep him present’
Emma said: "He died in December, and then in March we went into lockdown. So his past two birthdays we haven't been able to celebrate.
"Doing this kind of thing does help me, not just fundraising, but raising awareness about these symptoms.
"I've got messages from people who said they wouldn't have taken the child to the hospital if it weren't for me that ended up being sepsis or something quite serious.
"It's hard because while it is like a really good feeling knowing you're making a difference, I wish it were me telling this story, but we manage alright.
"One of my best friends has got a son the same age, two weeks apart. Watching him go to pre-school was hard. It's difficult because he should be starting school in September."
Emma said Ezra's elder sister, Isla, who is now nine, 'misses him a lot' and they are 'trying to keep him present and talk about him'.
She added: "We talk about him a lot and celebrate his life. As painful as losing him is, it's all worth it because we had him."
Emma and her partner, Ryan Goodjohn, 31, have since had another baby, Effie, who is now one.
A three-course dinner and entertainment
Ezra's Birthday Ball will be held at 6pm, August 5 at DoubleTree by Hilton on Chesterfield Road and will include a three-course dinner and entertainment from singer Salli Flaherty.
Additionally, there will be a silent auction where attendees may bid on a signed Sheffield Wednesday ball and a signed Sheffield United shirt, among other items.
There will be a raffle too, dubbed Ezra's Golden Ticket, in which participants can pay £5 for an envelope containing a prize.
She also said they are looking for businesses who would like to donate or sponsor a table.
Each ticket costs £42 and tables of 10 guests can be purchased for a reduced rate of £400.