The male patient, 28, had been diagnosed with Covid-19 after returning from the United States on March 27.
He was put into isolation at Queen Elizabeth Hospital before he was transferred to the North Lantau Hospital Hong Kong Infection Control Centre (HKICC) to wait for a confirmatory test, and for gene sequencing to be performed on the coronavirus he was carrying.
The HA said initial tests conducted by Department of Health found that he was not infected with a particular mutation of the coronavirus known as N501Y, which is commonly found in a UK variant of the virus.
Staff then followed the usual practice of putting him together with three other confirmed patients on the afternoon of March 28.
He was with them for more than a full day before further sequencing tests found that the virus he was carrying had the E484K mutation – which scientists say may be more resistant to immune responses and render vaccines less effective.
The HA said the three exposed patients, along with the index patient, were subsequently isolated separately from 1am on Tuesday.
“HKICC will continue to closely monitor the condition of the four patients and communicate with the Centre for Health Protection (CHP) on the isolation and quarantine requirements for these patients, ” an HA spokesman said.
“The HA will deliberate further with the CHP and relevant experts on enhancing the workflow of the gene sequencing tests and the subsequent patient isolation arrangement,” he added.
The latest case came on the heels of a separate incident involving a woman infected with the UK variant, who was accidentally placed in the same cubicle as four other patients for 20 minutes last Friday.
The spokesman also stressed that no ‘variants of concern’ (VOC) – or mutations that can make the coronavirus more contagious or deadly – have been identified in any local Covid-19 cases so far.
Separately, an expert committee looking into the deaths of patients after receiving coronavirus jabs has looked into six more cases, and again found no direct link between the vaccinations and the fatalities.
The committee has now concluded that eight of the 13 fatalities being looked at have no causal relation with the Covid vaccines.