The Early Childhood Council says 40 percent of its members expected to lose unvaccinated teachers today.
The government's vaccine mandate means staff without a Covid-19 vaccination are not allowed at work.
The council says 370 of its members responded to a survey.
Thirty-one percent said they would lose one or two teachers and 10 percent said they would lose between three and five.
The council says centres will have to send children home if they do not have enough staff to maintain minimum staff child ratios.
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