Dutch scientists have so far identified 13 cases of the Omicron variant of coronavirus among the 61 people who tested positive after flying to Schiphol on two flights from South Africa on Friday.

The research is still ongoing and more cases maybe found, public health institute RIVM said on Sunday afternoon.

Everyone on board the flights – a total of 624 people – was tested for coronavirus before they were allowed to leave the airport. Most of the people who have the virus were taken to a hotel for the duration of their quarantine period, but five people, who live alone, were allowed home.

The Omicron variant was first identified in South Africa but has already turned up in Belgium, Germany, Britain and several other countries.

The Netherlands is now urging some 5,000 people who have travelled to the Netherlands from southern Africa since November 22 to make an appointment for a test, even if they don’t have any symptoms of the virus.

Health minister Hugo de Jonge said on Sunday he did not rule out imposing extra measures to try to deal with the new variant, but much depends on how infectious and how serious it is.

‘The World Health Organisation has described it as a variant of concern,’ De Jonge said. ‘We are worried, but we will only know how worried we should be in the coming weeks.’

Flight ban

De Jonge said it is not possible to halt all flights from southern Africa, as some have suggested, because people from the EU have a right to return home.

Everyone flying in from southern Africa will have to go into quarantine at home for at least five days and checks will be carried out on everyone to make sure they do stay in, De Jonge said. This will involve a phone call and a home visit.

The regional health board has also opened a special testing area at Schiphol airport for passengers flying in from South Africa.