"Harry Potter" star Jessie Cave revealed her infant son, Abraham, has been hospitalized with coronavirus.

The 33-year-old actress, who played Lavender Brown in the blockbuster movie franchise, shared the news on social media on Tuesday. 

"I watched the news about lockdown from an isolated room in hospital," she wrote. "Poor baby is covid positive. He’s okay and doing well but they are being vigilant and cautious, thankfully."

Cave continued: "This strain is super powerful and contagious so I do hope that people take extra care in the coming weeks. Really didn’t want this to be the start of my families [sic] new year. Really didn’t want to be back in a hospital so soon after his traumatic birth. Once again I’m in awe of nurses and doctors.

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"He's 9llbs 7 now so he's a stronger and bigger boy than he was when we were last in a hospital room (and the needle went into his hand with louder more powerful screams 😣😣😣😣😣.)," she added. "Love and best wishes to everyone ❤️ 🏥 #nhsheroes #nhs."

Abraham was born in October and joins siblings Margot, 4, and brother Donnie, 6, whom Cave shares with her husband, Alfie Brown.

On Monday, British Prime Minister Boris Johnson ordered a national lockdown in the United Kingdom through mid-February in an effort to combat a variant of the coronavirus that is continuing to rapidly spread in the region.

Jessie Cave's infant son tested positive for coronavirus. 

Jessie Cave's infant son tested positive for coronavirus.  (David M. Benett/Dave Benett / Getty Images for Shortlist Media)

"We now have a new variant of the virus and it's been both frustrating and alarming to see the speed with which the new variant is spreading," Johnson said in an address.  

Under the rules, which are set to go into effect as soon as possible, primary and secondary schools, and colleges will be closed for face-to-face learning except for the children of key workers. University students will not be returning until at least mid-February.

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Non-essential businesses such as hair salons and restaurants will be closed, although eateries can operate delivery services. As of Monday, England reported more than 26,600 COVID-19 patients in hospitals, which is a 30% jump from a week ago. 

Fox News' Greg Norman contributed to this report.