West Australian health authorities have discovered a breach in Covid-19 protocols during the transfer of an infected crew member from a ship, forcing one person into quarantine and exposing more than 50 others as casual contacts.

A staff member was potentially exposed to the virus after entering a lift that the infected crew member, from MV Emerald Indah, had been in at Geraldton Health Campus.

WA Country Health Service principal health officer Helen Van Gessel told reporters on Wednesday that the error was identified immediately.

“The breach occurred when a staff member, who wasn’t involved in the transfer of the patient, entered the lift that the patient had been in before it could be appropriately cleaned, and that staff member was not wearing PPE,” she said.

“This error was immediately identified. The staff member was sent home to isolate immediately and didn’t have any contact with the community.”

The staff member is fully vaccinated but will be required to quarantine for two weeks and be tested because they have been deemed a close contact.

The seafarer was initially taken to Geraldton Health Campus on Sunday evening before being transferred to Perth, where he remains in a stable condition.

Public Health Emergency Operations strategy co-ordinator Clare Huppatz said authorities had examined the patient’s full journey with a fine-tooth comb.

She said so far authorities had identified 28 staff, 18 patients and five visitors to the emergency department who were not wearing PPE and were therefore considered casual contacts.

“The patient was in the emergency department for longer than you would normally expect – up to three hours,” she said.

“There’s a very small risk because of that, that there might have been a transmission event inside the emergency department.

“I need to add that this is out of an abundance of caution that we’re making this call.”

The casual contacts can “go about their normal business” but must be tested three times during the next 14 days.