WARRINGTON, United States -- When British couple Alison and David Henry booked to visit their son Liam in New York in March last year, little did they know Covid-19 would delay the trip by nearly two years.

In the meantime they missed celebrating their son's 30th birthday and their own 30th wedding anniversary together, while Liam contracted the virus and Alison was diagnosed with skin cancer.

"It's been so hard," a tearful Alison, 63, told AFP in the family's home in Warrington, northwest England, as they prepared to finally make the journey to the United States.

"I just wanted to go and be his mum, but we just couldn't get there," she added, noting her melanoma diagnosis made the upcoming visit "all the more poignant".

"I just want to see my son." The United States will reopen its land and air borders from Monday to fully vaccinated foreign visitors.

The move will end a more than 18-month ban on travel from much of the globe that separated families like the Henrys, hobbled tourism and strained diplomatic ties.

Together with Alison's 87-year-old mother Pat Sanderson, the trio from Warrington are set to be among the first to land in the US from Europe next week.

"I can't wait," said Pat, sipping a gin and tonic on the family couch ahead of the flight from London's Heathrow Airport early Monday.

"It'll be nice to walk up and put my arms around him," she added of her grandson.

- 'Frustrating' - Liam, now 31, moved permanently to New York in 2017 after meeting his boyfriend Jeremy there.

His parents last visited in 2019 -- the longest period apart ever for the close-knit family.

David, 74, recalled they were "devastated" when their original trip to see their son was cancelled at the last minute as the pandemic swept the world early last year.

Despite speaking to Liam online once a week, it has lacked the intimacy of in-person meetings, he said, and he looks forward to being able to hug and enjoy simple pleasures like sharing meals again.

"We didn't know how long it would be -- we never envisioned it would be this long before the USA would open up," David added.

His wife noted the anxious wait for US travel to restart had been made all the harder by US citizens being able to visit Britain since the summer.

"It was really frustrating," she said. "We've seen Donald Trump here, and then Joe Biden here, and it's like: 'Well, you're over here, why can't we come over there?' It's unfair." As well as getting PCR Covid tests and completing various paperwork, the family has also been busy assembling Liam's favourite things from his homeland, including British tea, biscuits, mustard -- and some homemade sticky toffee pudding.

"I hope we can take it through!" Alison said, fearing airport security may confiscate her creation.

- 'No end in sight' - Meanwhile Isabelle Karpinski, 26, an American living in the United Kingdom since 2014, was forced to repeatedly postpone a trip home to Mississippi to introduce her boyfriend, also called Jeremy, to relatives.

The London-based couple had planned the trip -- 27-year-old Jeremy's first to the US -- pre-pandemic but were forced to repeatedly reschedule and then cancel it.

They are now finally set to join her Polish-born parents for Christmas.

"It's just been waiting, and everything's kind of out of your hands," she told AFP.

"It was a bit surreal and definitely frustrating to just see the trip getting pushed and pushed and pushed, and then just fully cancelled." Karpinski said she was reluctant to visit her family, which includes elderly members, until everyone was fully vaccinated, and at times it had felt like there would be "no end in sight" to the pandemic curbs.

"It was like: Am I going to see my family again?" Now, with transatlantic travel finally back, she is left with the more typical concerns of a partner about to introduce their other half to their parents.

"They're gonna get along swimmingly, so I'm not really too worried," the film and television industry researcher said.

"It's Christmas, so who wouldn't be excited?"