Gavin Roberts, who celebrated his 12th birthday on Sunday, had repeatedly asked his mother, Alice Roberts, for the vaccine after the death of his father Charles Roberts from Covid.
Mr Roberts, who was 45 years-old at the time of his death, had been a police officer with the Glen Ridge Police Department when he caught the virus and died. There were no vaccines available at the time.
Ms Roberts said her husband had been healthy and took the pandemic “very seriously” before collapsing and being taken to hospital, where he died on 11 May 2020.
She said of their son, Gavinn: "I kept asking him what he wanted for his birthday, [and] He was always saying it's the vaccine, we're going to get that."
The school teacher also told NBC New York that when vaccines did become available for herself and Gavin’s two older sisters, all of her family all got jabs because it was “the only way out of the pandemic”.
"Throughout this whole experience, we’ve felt that if we can turn a really sad, horrible moment in our lives into something that can help people we want to do that," Ms Roberts said.
Gavin told the network that “he hoped people just learn that its very hard to go through”, when you lose a family member from Covid, and that he hoped people saw that it was preventable with the vaccine.
“By seeing us, hopefully it personalises it for people and it’s a real thing and it really happened to us. We’re not paid actors. It really happened and it can happen to anyone,” Ms Roberts added.
In a opinion piece for NJ.com, she criticised some first responders and law enforcement who were most at risk from Covid, but who were “not vaccinated and are against the mandates”.
It comes after US President Joe Biden announced a mandate for employers with more than 100 staff to ask workers for proof of vaccination against Covid.
Children aged below 12, meanwhile, will soon be approved for a vaccine, manufacturer Pfizer said on Monday.