Prince Charles and Camilla, Duchess of Cornwall also sent birthday wishes to Meghan Markle and Prince Harry's son with a message on their Clarence House Instagram

Happy 2nd birthday Archie!

The son of Meghan Markle and Prince Harry (and soon-to-be big brother!) received birthday wishes from some of his royal family members early Thursday morning.

Queen Elizabeth sent her great-grandson a birthday message via the official Royal Family Instagram account.

"Wishing Archie Mountbatten-Windsor a very happy 2nd birthday today. 🎈," read the caption alongside a snapshot of a newborn Archie with his proud parents.

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"Happy birthday to Archie, who turns two today. 🎂," Prince Charles and Camilla, Duchess of Cornwall wrote on the Clarence House Instagram accompanying a black-and-white throwback photo of Harry with his then-newborn son.

Harry, Duke of Sussex; Meghan, Duchess of Sussex
Meghan Markle and Prince Harry with son Archie in 2019
| Credit: DOMINIC LIPINSKI/AFP via Getty Images

Prince William and Kate Middleton got in on the celebrations too, wishing their nephew across the pond "a very happy 2nd birthday today" alongside a group family photo from Archie's July 2019 christening.

Meghan and Harry also shared a new photo of Archie holding a bouquet of birthday balloons on their Archewell Foundations website, along with a request for fans to donate to vaccine equity in honor of Archie's second birthday.

Archie Mountbatten-Windsor
Archie's recent birthday image
| Credit: The Duke and Duchess of Sussex

"We will not be able to truly recover until everyone, everywhere, has equal access to the vaccine," the couple wrote. "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 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. Together, we can uplift, protect, and care for one another."

Prince Harry, Meghan Markle
Prince Harry, Meghan Markle and Archie
| Credit: Toby Melville/Samir Hussein/WireImage

Amid the birthday celebrations for her son, Meghan, 39, recently announced that she has written her first children's book, inspired by her husband and son's relationship.

"The Bench started as a poem I wrote for my husband on Father's Day, the month after Archie was born," Meghan said in the press release from publisher Random House Children's Books. "That poem became this story."

RELATED VIDEO: Meghan Markle and Prince Harry Announce They Are Expecting Baby No. 2

In February, Meghan and Harry, 36, excitedly announced they are expecting their second child this summer. "We can confirm that Archie is going to be a big brother. The Duke and Duchess of Sussex are overjoyed to be expecting their second child," a spokesperson for the couple told PEOPLE at the time.

In March, they shared the news that Meghan is pregnant with a baby girl. "To have a boy then a girl — what more can you ask for?" Harry said during the couple's sit-down with Oprah Winfrey.

The growing family has been settling into life in Montecito, California, since their move last summer.

"They are both extremely attentive parents. Harry wants to give Archie the childhood he always wanted," an insider previously told PEOPLE. "They spend a ton of time outside, and both Harry and Meghan love to play — all the private space is a dream for them."