evidence: In one sense it is an easy question to answer. Samoa’s vaccination rate was too low to protect its people when measles arrived, probably brought by a traveller from New Zealand, which has suffered its own measles outbreak over the last year. [...] The rate plummeted sharply after a scandal that rocked Samoa in July 2018, when two Samoan nurses administered MMR vaccines to babies who subsequently died. The problem was not with the vaccine, an investigation determined, but rather its administration, after it emerged that one of the nurses mixed the MMR vaccine powder with expired muscle relaxant anaesthetic instead of water. [...] "These outbreaks just don’t happen by themselves in places like Samoa," says Hagan. "They’re really isolated and they haven’t had any cases in years and years … the fact that this measles outbreak is whipping around the world on airplanes, which is really a global failure to protect children against this horrible disease."