Measles cases spike worldwide

UK health officials are urging people to make sure they are vaccinated against measles following the death of a child from the disease in Liverpool. There has been a huge surge in cases in parts of the UK over the last couple of years, as well as across Europe. The United States is also experiencing its worst measles outbreak in decades. The cause is solely down to under-vaccination: migration from parts of the world with weaker public health and vaccine programmes, as well as poor uptake in the country means we’ve fallen below the protective “herd immunity” threshold needed to keep everyone safe. Michael Marks is professor of medicine at the London School of Hygiene and Tropical Medicine…

Michael - Measles is a viral infection. And historically, it was a very common infection of children. And most people who get measles will have an illness where they may have fever, sore eyes, and characteristically a rash over their whole body. And the proportion of people that get measles will become more unwell with that. They may get pneumonia, a chest infection. And some people will have an infection of the brain. But some people can get much more seriously unwell.

Chris - We've luckily got a vaccine these days, haven't we? Is that particularly effective or ineffective?

Michael - So it's a very good vaccine, probably one of the best vaccines that we have. If you've had all of your doses of measles vaccine, it's probably more than 95% effective at stopping you getting measles. What we know is that measles is very, very infectious. So I'll try and give a comparison to help people understand. If you think about probably the biggest virus we've all talked about in the last five or six years, which is COVID. On average, one person with COVID will transmit that virus to two or three other people. Measles, if you had a room full of people, all of whom had not been vaccinated, and there was one case of measles, that person might spread the measles virus to 16 to 20 people. So it is much, much more infectious than all other viruses. And that's why the vaccine is such a critical part.

Chris - So if we've got amazing vaccines that are effective in the way you say, at combatting one of the world's most infectious viruses, why have we got outbreaks?

Michael - The first is that because this is probably the most infectious virus we know of, in order to stop spread between people, you need to have a really, really high rate of vaccination in the population in or around 95% of people. So that's the first thing, you need a really high level of vaccine in the community. And unfortunately, for a number of reasons, rates of vaccination in many parts of the community are much lower than that, they might be 75 or 80%. And although that still sounds very high, because measles is so infectious, you need to get this really, really high level of vaccination to stop transmission.

Chris - Many of the victims are really little kids, as in they're under one year old when we get really bad cases, and in some cases, unfortunately, deaths. But we don't give the vaccine until more than one year of age. So that seems a bit illogical. Why would we wait when the vulnerable period is younger than the age we're vaccinating if the vaccine is so effective?

Michael - If we can vaccinate enough of the population, then we can stop the virus spreading. And that protects those individuals, in this case, young children who haven't yet had a chance to be vaccinated. And that is a concept that has been called herd immunity. So this is the idea that if enough of the population are immune, they cannot catch the virus, they therefore cannot spread the virus to other people. That protects those individuals who because of their age, or because of other medical reasons, can't receive the vaccine. So that's the strategy that we rely on. But it does, as I've said, mean we need to get really, really high vaccination rates in order to protect those individuals who haven't yet had a chance to be vaccinated.

Chris - So why don't we just vaccinate them younger?

Michael - The baby's immune system is still maturing, you need the right cells to make a good response to that vaccine. Because what you don't want to do is give the vaccine, and it only protects you for six months, and you have to vaccinate again, and again, and again. And what we've been able to establish through studies, if we vaccinate young children at a year, and then they receive several other doses in their young childhood, they develop immunity, protection from measles that lasts for life. So we've got a schedule of giving the vaccines to the children when we know that they will respond well, and that they will develop protection for themselves for life.

Chris - What's the reason then for the under-vaccination that's going on? It's not just the UK, we've had big outbreaks in the US, in Texas, they've had enormous numbers of cases there, in Europe, many, many countries in Europe that previously have very low levels of measles activity have seen in recent years a big spike again, all attributable to low levels of vaccine uptake. What's behind this?

Michael - We have grown up over the last 20 or 30 years when we have had this vaccine. And so most people don't have the experience of seeing this disease and understanding how devastating it can be. So that I think is one part. And then the other part are that people have very incorrectly raised a number of concerns over the safety of the vaccine, they have said that the vaccine might cause serious side effects. But really, there is comprehensive data from many, many countries and millions and millions of children who have been vaccinated that show that this is a very, very safe vaccine. So unfortunately, we have this perfect storm, disinformation, incorrect information being shared, telling people that the vaccine is not safe, when the vaccine is perfectly safe. And at the same time, people feeling like maybe measles isn't such a big problem. And so we're seeing those two things come together now. And that is meaning that we only have 70 or 80% of the population being vaccinated, and many, many children acquiring measles, some becoming sick, and unfortunately some dying.

Chris - Do you think the problem will just take care of itself then? Because so many people will catch it that one of those reasons you've highlighted, which is that people haven't seen cases, therefore they don't know how dreadful this is, it will educate people, and perhaps it will flip the pendulum back the other way. Or do you think we're actually going to have to do something about this?

Michael - We will have to do something about it. This sort of disinformation, this misinformation, it's so pervasive now. And we're seeing it spread almost like a virus freely. It's not just measles vaccine, you know, we're seeing declines in the rates of many, many childhood vaccines, uptake, as you say, not just in the UK, but across Europe, across North America. And I think we will need public health efforts, both to reassure the population about the safety of the vaccines. And we'll need to think about, you know, campaigns, for example, catch up campaigns for children that have missed these vaccines. Now you're three or you're four or you're five, we need a program in place to let you catch up and be vaccinated.