Archie Sussex, the oldest child of Prince Harry and Duchess Meghan, is turning 2.

The young royal and great-grandchild of Queen Elizabeth and the late Prince Philip is expected to celebrate his second birthday in California, where his family moved last year from the United Kingdom.

Archie's parents, Harry and Meghan, put out a fundraising request in honor of their son's birthday to help provide COVID-19 vaccines to people in developing countries.

Along with a letter posted on the website of their Archewell non-profit foundation, the couple shared a photo of their 2-year-old son holding a big bouquet of balloons outside.

PHOTO: Prince Harry and Meghan shared a photo of their 2-year-old son Archie on his birthday on their website Archewell.com.
The Duke and Duchess of Sussex
Prince Harry and Meghan shared a photo of their 2-year-old son Archie on his birthday on their website Archewell.com.

"We have been deeply touched over the past two years to feel the warmth and support for our family in honor of Archie’s birthday," Harry and Meghan wrote. "Many of you donate to charities on his behalf, and mark the occasion by giving back or doing an act of service—all through the goodness of your hearts. You raise funds for those who need it most, and continue to do so organically and selflessly. We remain incredibly grateful."

The Sussexes go on to describe the need for vaccines in developing countries amid the ongoing coronavirus pandemic, and then added their fundraising plea for Archie's birthday.

"We will not be able to truly recover until everyone, everywhere, has equal access to the vaccine. And with that intention, we are inviting you to contribute whatever you can—if you have the means to do so—to bring vaccines to families in the world’s most vulnerable places," they wrote. "For a donation of just $5, you can cover the cost of a dose for someone in need. And because we were able to secure matching support from a number of organizations, that $5 you give will automatically turn into $20—covering the cost of four doses. Every single dollar counts—not only will it help save lives but it will help save families and communities."

Harry and Meghan added, "We cannot think of a more resonant way to honor our son’s birthday. If we all show up, with compassion for those we both know and don’t know, we can have a profound impact. Even a small contribution can have a ripple effect."

In addition to his parents' letter, Archie received birthday wishes on social media from his family members in the U.K., including his great-grandmother, Queen Elizabeth, his uncle and aunt, Prince William and Duchess Kate, and his grandparents, Prince Charles and Camilla, Duchess of Cornwall.

Archie will become a big brother this summer, when Meghan is expected to give birth to her second child, a girl.

"Amazing. Just grateful," Harry told Oprah Winfrey in March about becoming a father again. "To have any child, any one or any two, would have been amazing, but to have a boy and then a girl, I mean, what more can you ask for?"

"Now we've got our family," he said. "We've got, you know, the four of us and our two dogs."

Archie has only been seen publicly a handful of times in his first years of life, but Harry and Meghan gave a glimpse into his life during their tell-all interview with Winfrey.

The Sussexes revealed Archie is "on a roll" with his vocabulary, most recently saying "hydrate" and telling visitors to the family's Santa Barbara-area home to "drive safe."

"Whenever anyone leaves the house, he's like, 'Drive safe,'" said Harry.

Harry, who grew up living in royal palaces in the U.K., spoke about Archie when asked by Winfrey what he cherishes most about his life in the United States.

"I guess the highlight for me is sticking him on the back of the bicycle in his little baby seat, and taking him on these bike rides, something which I never was able to do when I was young," Harry said. "I can see him on the back, and he's got his arms out and he's like, 'Wooh,' chatting, chatting, chatting, going, 'palm tree,' 'house,' all this sort of stuff."

"And I do, I think to myself, wow," said Harry, who added he also loves going on hikes and going to the beach with Archie, Meghan and their dogs.

The Sussexes shared with Winfrey what appears to be family footage of Archie playing on the beach with Meghan and one of their dogs.

PHOTO: Meghan, Duchess of Sussex, is pictured playing on the beach with her son Archie in an image from an interview with Oprah Winfrey, that aired March 7, 2021.
Harpo Productions/CBS
Meghan, Duchess of Sussex, is pictured playing on the beach with her son Archie in an image from an interview with Oprah Winfrey, that aired March 7, 2021.

At the family's multi-million dollar home in Montecito, California, Archie is known to have an outdoor playhouse that was the setting for the family's Christmas card last year.

Archie also has a chicken coop on his family's property that is named after him.

PHOTO: Meghan, The Duchess of Sussex, speaks to Oprah Winfrey in an image made from video that aired on CBS, March 7, 2021.
Harpo Productions/CBS
Meghan, The Duchess of Sussex, speaks to Oprah Winfrey in an image made from video that aired on CBS, March 7, 2021.

Winfrey and Harry and Meghan filmed inside the coop, which hosts a sign that reads, "Archie's Chick Inn — established 2021."