Mastitis requires throwing out milk and spreads easily, so farmers are pretty quick to cull chronically infected cows. 25% of culls are for mastitis or other udder problems.
Small error: the linked article states 15% of culls were for “mastitis or udder”, not 25% .
https://www.thecattlesite.com/articles/695/guidelines-to-culling-cows-with-mastitis/
I would also take slight issue with the statement above because it implies culling is done to prevent transmission. Per the article aggressive culling doesn’t stop transmission, so culling is only done if the animal itself isn’t economically viable due to low milk production or chronic infection. Only some mastitis is transmissible, and per the article, hygiene, not culling, is the most economical way to deal with it.
Without a vaccine, where we are now is where people were before the chicken pox vaccine; if you’re a woman of reproductive age and planning to have children, you actually want to have it already, because primary infection during pregnancy is so dangerous.
In my personal life I’ve met two children with congenital CMV. One lived only a few days after birth, the other came close to death in infancy but survived but with lifelong disabilities, both physical and cognitive. In my view a vaccine can’t come fast enough!