The Catechism in Questions & Answers

447. Did the Apostle ministry cease to exist after the death of the early Apostles?

The Apostle ministry continued to exist despite the fact that the Apostles died. This ministry has been instituted by Jesus Christ for His church. Even during the time when there were no bearers of this ministry on earth, the ministry established by Him was still present.
The Apostles are to be witnesses of Christ until the end of the age (cf. Matthew 28: 19-20). In order to fulfil this comprehensive task in view of His return, Jesus Christ also sends Apostles today.

“End of the world”: The Greek original text of Matthew 28: 20 uses the term aeon, which can refer to an era, a long period of time, or also “end of the world”. There is a similar reference to the “end of the earth” in Acts 1: 8, but this is meant in geographical terms.