The Catechism in Questions & Answers

569. Will there be any protection in the time of the “great tribulation”?

Yes. In the time of the “great tribulation”, there will be a place of spiritual protection for those who belong to the church of Jesus Christ and who have not been caught up to Jesus Christ. They will continue to experience divine help and spiritual care so that their faith may be preserved.
In the book of Revelation, they are represented by the image of the woman clothed with the sun, who has given birth to a male child. They continue to receive divine support and spiritual care such that their faith may be preserved (cf. Revelation 12: 6).
In the time of the “great tribulation” there will be people who are killed for professing Christ. These steadfast witnesses will thus become martyrs.