I'm a big believer that increased herd sizes are the greatest method in EEHV prevention. Asian and African elephants both congregate regularly in large groups outside of their natal herd and these interactions both socialise and immunise juvenile calves. Hopefully in the long run Werribee's herd will reflect successful zoos with low EEHV death rates like Carbaceno and African Lion Safari. The only issue in the meantime is growing their numbers to the size (20ish) where EEHV presents less of a threat. Currently, Australia has a calf survival rate of roughly 60%, which suggests that ZoosVic will need to produce a whopping 15-18 calves over the next couple of decades to grow themselves out of the EEHV 'danger-zone'.
This makes me wonder whether sending Pak Boon and Tang Mo to Werribee is a better idea than to Monarto. The more elephants in one place the better imo, increasing the exposure for their three young calves. This would leave Monarto as a retirement/bachelor facility but I'd rather have one large successful breeding facility than two smaller ones scourged with EEHV.
It also makes me wonder whether Man Jai being completely separated from all the cows for 10-11 months now was a bad decision, reducing his exposure and resulting in a drop in his antibodies. I understand he and Luk Chai would have been disruptive to the herd and annoyed the cows, but a bit of adversity would've been good for development. Even then, separate contact with Kulab and Mek Kappah could have been achieved with Man Jai and Luk Chai.