Coronavirus cases in four states have forced the closure of two Sydney schools just a day after reopening, and prevented the departure of a live export ship in Fremantle.

Two schools in Sydney’s east, Waverley College and Moriah War Memorial College, were evacuated on Tuesday after boys in year five and year seven tested positive to COVID-19.

On the other side of the country, six crew from the Al Kuwait, a live export ship from the United Arab Emirates, tested positive to the coronavirus. Western Australian Premier Mark McGowan said he expects more cases among the 48 crew members.

And SA Health said a woman in her 50s who travelled from Victoria had been confirmed with COVID-19 after arriving in Adelaide on the weekend. She was granted permission to fly to SA for family reasons.

The Al Kuwait docked in Fremantle on Friday. Mr McGowan said Commonwealth authorities had given it permission to dock, despite three crew members reporting elevated temperatures.

“Straight away, I had thoughts of the cruise ship saga. I thought these kinds of situations were behind us,” he said.

Ms McGowan said the situation with the Al Kuwait was evolving quickly. The infected crew were being quarantined at a Perth hotel while the others remained on the ship.

“I suspect it is probably more than likely that more crew members may become infected with the virus,” he said.

“There is an extremely concerning situation that we find ourselves in.”

Earlier on Tuesday, the two Sydney schools closed immediately after a boy from each tested positive for the coronavirus just 24 hours after a return to classrooms across the state.

About 9am on Tuesday, parents of students at Waverley College in Sydney’s east were issued with a note to “immediately” come and pick up their children after a year seven boy tested positive.

Later in the morning, at Moriah War Memorial College in Queens Park, just 1.5 kilometres away, a year five boy also tested positive.

A note sent to parents of Waverley College students read: “A member of the senior campus has tested positive for COVID-19 and is in isolation”.

The school said staff “immediately activated our critical response to get the boys home quickly and safely”.

“Those students who were unable to have parents collect them immediately were sent directly home on private buses that the College organised.”

“Staff had been preparing for some time, because the school was in a hot spot.”

Waverley College deputy principal Patrick Brennan also said the school had procedures to deliver schooling online if an extended closure was necessary. The school will be deep-cleaned and re-opened after a NSW Health investigation.

Nearby, Moriah college, a modern Orthodox Jewish school, closed about 12pm on Tuesday after it received confirmation from NSW Health a student, who was on campus on May 21, had tested positive for COVID-19.

In a statement the college, which started bringing students back on May 7, said it had activated its evacuation plan and was planning to re-open on June 1. Teaching would be continue online until then.

“In accordance with NSW Health advice, the college has closed whilst contact tracing is conducted, and the school is cleaned and sanitised,” it said.

Moriah College in Sydney’s east was  the second school to close. Photo: Google Maps

Meanwhile, in Victoria, a Melbourne teacher was confirmed to have the coronavirus, ahead of 400,000 public school students returning on Tuesday.

The teacher, who was one of 17,500 staff tested ahead of Victoria’s staggered reopening of primary and secondary education, had not been at school.

The teacher at Keilor Downs Secondary College tested positive on Friday. State Education Minister James Merlino said they had not been at the school, and close contacts weren’t identified on site, so no further action was needed.

Infectious disease experts say it is “extremely rare” to see COVID-19 cases among children, an age group not considered highly infectious amid the pandemic, compared to the flu.

Consultant paediatrician Kirsten Perrett told the ABC: “Most of the time [with] respiratory viruses such as influenza, children are actually more susceptible to infection and severe disease, but this is not the case that we’re seeing with COVID-19”.

“If this was influenza,” infectious disease physician and microbiologist Peter Collignon added, “we would keep schools closed until this was over”.

The Ruby Princess at Port Kembla south of Sydney after a NSW police launched an investigation. Photo: AAP

Another Ruby Princess passenger tests positive

A passenger of the ill-fated Ruby Princess who tested positive to coronavirus is suspected to have carried the “dormant” virus for almost 10 weeks before falling ill.

The woman was diagnosed in Cairns on Monday, taking the total number of Queensland cases to 1057, with just 12 remaining active.

Authorities suspect she is the latest case to have carried the inactive coronavirus and become sick weeks after exposure.

Last week another woman in Queensland was diagnosed two months after returning from India.

“We are monitoring that very closely to work out if it’s directly related to the Ruby Princess or if it was acquired in some other way,” Queensland Premier Annastacia Palaszczuk said.

A spokesperson for the health minister said the woman had returned a negative result after a recent test and it was not possible she was contagious since she left the ship on March 19.

-with agencies