Measles cases triple in a year

Cases of measles virus have tripled since last year, new figures from the Word Health Organisation reveal. In 2018, numbers were already significantly higher, with nearly 150,000 people dying of the infection and an estimated 10 million infected. The United States has reported its highest number of cases in 25 years, and four countries in Europe - including the UK - lost their measles elimination status following long-term outbreaks of the disease. This week, in the grip of a massive outbreak, the Pacific island of Samoa declared a curfew and a mass vaccination campaign to try to stop it. So why is this happening, what will be the consequences, and what can be done to stop it? Chris Smith asked Freya Jephcott, who studies disease outbreaks at the University of Cambridge…

Freya - Well, I guess the short answer is that vaccination coverage has dropped, but then when we try and understand why vaccination coverage is dropping, we have to look at, sort of, individual countries and take it region by region.

Chris - Why is measles such a scourge?

Freya - Measles is incredibly infectious. I think people somewhat underestimate quite how infectious it is. So if say none of us were vaccinated, and someone with measles was walking around, that one person would be expected to infect maybe 16 to 18 other people.

Chris - How would that compare with say flu? Because that's infectious too.

Freya - Well, I think a really good point of comparison is maybe Ebola because that's also in the news at the moment. Ebola is typically, you could expect a case to maybe infect one or two other people.

Chris - So yes, it is the king of infectious viruses then?

Freya - Very much so.

Chris - And so the point is that once it gets a toe hold, it really goes to town quickly. It spreads like wildfire.

Freya - It's incredible. I think that Samoa makes a really good case for this. So just since October they had 4,500 cases and we're talking about a country with only 200,000 people.

Chris - And it's not trivial once you catch measles, is it? Because the death toll, I mentioned there in the introduction 150,000 people that we know about in 2017/18. Each year we're seeing these big numbers. That's probably the tip of the iceberg though, isn't it?

Freya - Absolutely. I think this is one of the things underlying low vaccination rates, especially in North America and Europe, is that we've largely forgotten quite how dangerous it can be.

Chris - And when people talk about vaccines, how does this actually work to curtail the spread of these things and why are we getting low uptake of vaccines?

Freya - So the measles vaccine does two things for us. It protects us on an individual level, so we can't get sick, but when we have 95% of the population protected, or ideally even more, then it can't spread through populations either. Which is great because not everybody can receive the measles vaccination, like babies under one for instance. So this protects them too.

Chris - And this is the concept of herd immunity, isn't it? The idea that you've got protection from being part of that herd where the vast majority of them cannot propagate measles?

Freya - Yeah absolutely, and I think in this day and age with sort of international travel and such, you've got to understand that the community we're trying to protect is much larger than just our local village town or country.

Chris - So Samoa have had a sort of lockdown, they've had a curfew, why will that work? Or will it indeed work? Because at the same time they've also started a mass vaccination campaign, because their vaccine rates are only about 30%. So now they've tripled them to about 90%, so they're close to the magic number that you're highlighting, but not quite there.

Freya - Unfortunately, Samoa was in the situation where they had a reactive measles vaccination, which is where, sort of, the cat's already out of the bag and you're doing everything you can to sort of limit the damage. So essentially they told everybody to stay home, to try and stop people who are potentially un-vaccinated mixing with infected people. Before that they had actually locked down the schools and stopped children going to any public places.

Chris - What's the lesson that we can learn from this and what might be therefore the next steps in trying to deal with the fact that we're just seeing this enormous escalation in numbers around the world?

Freya - Obviously the answer is getting vaccination rates above 95% across the world, but I think for North America, Europe, the Pacific islands, we've got to look at public health education and science communication. I think they're really the answers to getting rates back up.

Chris - Because you've helped to investigate and control Ebola outbreaks as well in your career, haven't you? And there must be some parallels here? Because one of the things that emerged when we had the huge outbreak in West Africa of Ebola in the last five years, five years ago, 2014 wasn't it? The people said that there was so much misinformation floating around that the local population didn't know the right thing to do, not to catch Ebola.

Freya - Ebola is slightly different in that it is such an unusual situation. Ebola outbreaks are really quite rare, that when they happen - and these large, quite strange responses, people in sort of spacesuits running around - it's quite a terrifying and novel experience for people. So then everything you're doing is kind of weird, intimidating and unfamiliar. I think maybe we have less of an excuse on the measles vaccination front. And again, we're aware that this is an effective, readily available way of protecting ourselves against this.

Chris - So don't take risks?

Freya - Yeah.