Hong Kong reports reinfection

Wasn't quite sure where to put this, so feel free to move this to a more appropriate forum.

https://www.bbc.com/news/health-53889823

Hong Kong scientists are reporting the case of a healthy man in his 30s who became reinfected with coronavirus four and a half months after his first bout.
They say genome sequencing shows the two strains of the virus are "clearly different", making it the world's first proven case of reinfection.
The World Health Organization warns it is important not to jump to conclusions based on the case of one patient.
And experts say reinfections may be rare and not necessarily serious.

My brother & SIL just visited us. She is a prof. in Boston at a university. She is the director of their Respiratory Care dept. She told me that there are currently SIX strains of the virus circulating. SIX.

And we're going to have a vaccine for which strain?