Ann: Letter to Shareholders, page-115

The vaccine they were able to create uses the standard system of stoping the s-protein or binding protein this process is the same for flu etc...
biotron however are working on a particle based treatment that attaches to main body of the virus and stops replication.
the current problem with the vaccine is that the s-protein is the first to mutate.
the particle however doesn't have any problems with these mutation(s) as the part of the virus it binds to has a very low chance of mutation.
this new particle treatment is quite novel in next generation treatment.
this is why it has taken so long.