Another Melbourne school has closed due to coronavirus concerns after three more Victorian cases were confirmed.

It brings the total number of cases in Victoria to 21.

In the most recent case, a man aged in his 50s became unwell on March 7, one day after arriving in Melbourne from the US.

The man worked at Yeshiva-Beth Rivkah College for half a day while infectious on March 9.

As a result, the school has been closed today as a precautionary measure while contacts can be identified and provided with advice.

Students are also being tested, with results due today.

“The Department is working closely with the school and Department of Education and Training to support students, parents and staff to ensure that all contacts are identified and the appropriate action is taken.

“For the virus to spread, extended close personal contact is most likely required. But visitors to locations where cases have been should be aware of the signs and symptoms of COVID-19. Close personal contact is at least 15 minutes face-to-face or more than two hours in the same room,” Victoria’s chief health officer Brett Sutton said in a statement.

All three cases confirmed overnight involved people flying from the US.

The 19th case is a man aged in his 50s who returned to Melbourne from Seattle on March 7 at 7am on Virgin Australia flight VA24.

After he arrived home, the man became unwell on March 7 with lethargy and dry cough, developing flu-like symptoms a few days later. He is now recovering in home isolation.

Passengers from that flight are being traced.

Both cases 20 and 21, the Yeshiva-Beth Rivkah College incident, were on flights from the USA which have had confirmed COVID-19 cases in passengers this week (UA0600 and QF94).

Both cases are recovering in home isolation and acquired the virus in the USA.

The Department of Health and Human Services is continuing to contact passengers on both flights UA0600 and QF94.