NPHET is worried about the significant number of people traveling abroad who have not yet been fully vaccinated.
It says while unvaccinated travel isn't fuelling another wave, it presents a real risk to individuals.
It's estimated that daily case numbers would currently be over 10 thousand if it wasn't for the vaccination programme.
Chair of NPHET's Modelling Group Professor Philip Nolan is appealing to people who are not vaccinated to cancel any planned holidays.
