Anne McCaffrey and Todd McCaffrey
The sequel to their two other collaborations, Dragon's Kin and Dragon Fire, Dragon Harper continues to chart the lives of Kindan and his friends. I'll admit that I haven't read Dragon Fire but this was followable even without that book.
However, it doesn't quite jibe with Moreta. That volume, though written earlier is set much later, and yet it seems that less of the knowledge was lost than was lost in this earlier time. Unless somehow they rediscovered the ability to immunize then lost it again before the events in that book.
With the ending of the story, I'm wondering what Anne and Todd McCaffrey are going to do next. They seem to have wrapped Kindan's story up pretty well with the epilogue.
Still, it's a good read, and the story holds together well.