The Netherlands' Institute for Health (RIVM) added in a statement that its investigation on passengers on the two flights has now been wrapped up.
The flights had already taken off on Nov 26 when the Dutch government introduced new travel restrictions due to worries about the newly detected Omicron variant.
More than 600 passengers travelling on the flights were kept isolated and tested for COVID-19, with 61 testing positive, including the 18 who were found to have the Omicron variant.
Those who tested positive but have no symptoms will be allowed out of isolation on Saturday while others will have to stay longer, the institute said.
It did not give details on the number of passengers that will be released from isolation.