Measles in Disneyland: the real stats behind the headlines

One of the biggest health stories in January was the measles outbreak at Disneyland in California, an event that threw a spotlight on the prominent anti-vaccine movement in the US. The movement started in the UK after Andrew Wakefield published his discredited and since retracted report on a supposed link between the MMR vaccine and autism. Once the report reached the US, it played heavily to the American sense of individual freedoms and fear of big government, quickly gathered pace with notable celebrity endorsements driving the movement forward.

Like many states in the US, California allows for an exemption from vaccines for undefined ‘personal reasons’. This has led to the MMR vaccination rate dropping to 90.7% (with a confidence of ±5.3%). With ‘herd immunity’ kicking in around 90-95%, this has made an outbreak almost inevitable.

On, we obviously pay a lot of attention to which diseases and conditions are attracting an unusual amount of traffic and even automatically tweet when a particular town or city in the UK is experiencing a ‘rush’ on a particular condition.

However, the measles outbreak was an entirely different beast. It (quite rightly) gained a lot of press coverage because it just shouldn’t be a problem in the developed world – measles is the leading cause of vaccine preventable death and considering that humanity eradicated smallpox back in the 70s, we really shouldn’t even be having this conversation.

The story broke around the 7-8th January and we immediately noticed an upsurge in traffic of 600%, something we can reasonably expect when a health story hits the news. What happened next was much more interesting though. If you look at our condition leaflet on measles you can see that the incubation period for the diseases is around 12 days.

Around 12 days after the original story broke, we can actually see the incubation period of the disease percolate through the news cycle and into our visitor stats. By the end of the month, we were receiving over 22,000 hits on our measles page, an increase of over 1750%! What’s more, the traffic was heavily skewed to the US, generally we get, at most 25% of our users from the US, however 85% of users viewing our measles content came from America. By the end of the month, our measles page was our most viewed page, jumping from 73rd all the way number 1 in a matter of days.

Despite the fact there were ‘only’ 141 reported cases, since the outbreak we’ve had nearly half a million users come to us for information about the measles, while you could chalk this up to an overreaction or somewhat irrational fear, if it means that some people change their mind about the supposed evils of vaccines and the true horrors of preventable disease then it has to be a good thing.