[Comment] Measles re-emergence in Mexico: essential public health functions under strain

Measles has re-emerged in Mexico and the country risks losing its WHO measles-free status.1,2 The resurgence is more than an epidemiological event: it is a stress test of health-system performance in essential public health functions—routine immunisation, surveillance, and front-line response.3 In unequal settings, measles outbreaks are rarely surprises; they are delayed confirmations of routine operational failure.