A 28-year-old male is currently in a life-threatening condition in an Abu Dhabi hospital, prompting fears over a new outbreak.
The man is believed to have contracted MERS (Middle East respiratory syndrome–related coronavirus).
The World Health Organisation said it would continue to monitor the situation in the region.
MERS is closely related to Covid-19 as another member of the coronavirus family - but it is not a strain of the same virus which caused the global pandemic, and was actually discovered several years earlier.
It was first identified by scientists in 2012, and is thought to have originated from an animal source.
It was identified at the time as a priority pathogen, as it causes a severe disease with a high mortality rate - although it is far less transmissible than Covid.
Symptoms include fever, coughing, shortness of breath, chills, body aches, sore throat, headache, diarrhoea, nausea/vomiting, and a runny nose.
The WHO said the latest MERS case involved a non-UAE national living in Al Ain, who had attended a private medical clinic multiple times between June 3 and 7, 2023, complaining of vomiting, right flank pain and pain when passing urine.
On June 8, he attended a public hospital with vomiting and gastrointestinal symptoms including diarrhoea and was given an initial diagnosis of acute pancreatitis, acute kidney injury, and sepsis.
The 28-year-old was in critical condition by June 13, and was referred to an intensive care unit (ICU) at a specialist hospital where was put on mechanical ventilation. He tested positive for MERS-CoV by PCR on June 23, 2023.
It is typically spread after people have been in contact with camels, however, the WHO said he has "no known history of direct contact with animals" including dromedary camels, and had not consumed their raw products.
He also had no known co-morbidities, no history of contact with MERS-CoV human cases, and had not travelled recently outside the UAE.
A total of 108 contacts were identified and monitored for 14 days from the last date of exposure - but no secondary infections were found. Before this case, the last MERS infection reported from the UAE was back in November 2021.
The first laboratory-confirmed case of MERS within the nation was in July 2013, and 94 cases of MERS-CoV have been reported since - with just 12 deaths associated with the virus in the last decade.