This threw already stalled talks about forming a new government further into disarray, setting them back by weeks if not months and making it virtually impossible to predict the outcome.
Rutte, 54, had narrowly survived a no-confidence vote on Friday after parliament passed a motion disapproving of his behaviour during government formation talks following last month's election.
He was supported by the two main parties that formed part of his previous coalition, the centre-left D66 and centre-right Christian Democratic Appeal (CDA), while all opposition parties voted against him.
The vote was to take place later in the day, after Rutte appeared in parliament to explain why he had told reporters he had not discussed a political appointment for one lawmaker, but it later emerged he had.
"He will get it done". The test is set for Wednesday, which is the period -- five days from being in contact with an infected person-- the Dutch health authorities advise for getting a test after such exposure.
Keijzer, who announced her infection on Twitter, was at a weekly Cabinet meeting on Friday attended by Rutte and more than a dozen senior government officials.
The election is widely seen as a referendum on the government's performance during the crisis, in which more than 15,000 people have died of COVID-related illnesses and police have clashed with protestors opposed to lockdown measures.
Rutte's main rivals have criticized a slow vaccine roll out, but struggled to distinguish themselves as they support government policy.
Meanwhile, an appeals court was hearing more arguments about whether it had ever been legal to introduce the curfew, which triggered street protests when it was brought in last month.
Protesters and political opponents say the curfew, the first seen in the Netherlands since World War Two, is a unnecessary restriction on freedoms.