New Zealand is in the thick of its worst measles epidemic in 22 years, with more than 850 cases so far. As one vaccinologist says, it was predictable, entirely preventable and the government were warned. So how did we get here? Jamie Morton and Natalie Akoorie explain.

Where did this outbreak come from?

Whittling this year's measles catastrophe down to a single origin is impossible, for the simple reason that there really isn't one. It's a messy story.

The first outbreak of measles in New Zealand this year began in the Waikato in January with 10 cases.

That strain came


What's the bigger picture, here?

How does this stack up with previous outbreaks?

So how does the MMR vaccine actually work – and what's herd immunity?

What's being – and should be - done?