A French noble winner said the virus has the dna sequence of hiv/aids. Search with "Luc Montagnier" for news. Can't link as it's controversial. But that spells trouble. Indicating vaccine makers might have some hard time. Or we might never be able to come up with an effective one.
Immunity once infected isn't guaranteed. South Korea is finding 2% getting reinfected after the first time.
https://edition.cnn.com/2020/04/17/health/south-korea-coronavirus-retesting-positive-intl-hnk/index.html