Measles is raging worldwide: are you at risk?
Summary
Measles is resurging globally: several countries have lost their measles-free status and the United States recorded more than 2,000 cases in 2025. The virus is extremely contagious (each case can infect an average of 12–18 others) and outbreaks are being driven by falling vaccination coverage. The measles vaccine remains highly effective (≈93% after one dose, ≈97% after two) and most vaccinated people are well protected; however, a minority experience ‘breakthrough’ infections that are usually milder.
Key Points
- Global resurgence: multiple nations (including the UK, Spain, Austria and Canada) have recently lost measles-free status; the US saw >2,000 cases in 2025.
- High contagiousness: measles has an R0 of roughly 12–18 and infects up to 90% of susceptible contacts.
- Vaccine efficacy: ~93% protected after one dose and ~97% after two; protection is generally long-lasting.
- Herd immunity threshold is around 92–95%; falling coverage (US kindergarten uptake fell from 95.2% in 2019–20 to 92.5% in 2024–25) opens the door to outbreaks.
- Breakthrough infections occur (≈12% of US cases from 2001–2022) but typically have milder symptoms and fewer complications.
- Travellers can spark transmission—prolonged exposure, such as on long flights, increases risk of spread.
- Modelling suggests more mixing between vaccinated and unvaccinated people raises the chance of breakthrough cases and sustained transmission.
Content summary
This Nature news piece by Mariana Lenharo outlines why measles is making a comeback: declines in vaccination coverage and increased opportunities for exposure are eroding herd immunity. The article summarises recent outbreaks, national changes in measles status, vaccine protection levels, and evidence that while vaccinated people can occasionally get measles, those cases are generally less severe. It uses US case data, a large South Carolina outbreak and an air-travel transmission example to illustrate how outbreaks start and spread.
Context and relevance
The article is important because measles is preventable but highly transmissible; reduced vaccine uptake and rising exposure mean outbreaks will become more frequent unless coverage improves. It ties into broader trends in vaccine hesitancy, public-health preparedness and travel-related transmission, so it’s relevant to parents, travellers, health-care workers and policy makers monitoring infectious-disease risks.
Why should I read this
Short and blunt: if you’ve got kids, travel, work in health care or just want to avoid avoidable outbreaks, this is worth five minutes. It tells you how protected vaccinated people really are (mostly fine), why outbreaks are happening now, and what to watch for — useful, practical and timely.