I just hope the vaccine can cover the broad range of EEHV. It seemed to me there is more than one strain, just like COVID with at least two or three because viruses have a way of evolving.
The vaccine is currently targeted towards EEHV1A, which is the most lethal strain in Asian elephants. You’re correct that there are multiple strains.
For the handful of elephants that have survived EEHV, it’s believed they henceforth have some level of immunity towards that strain.