Public Health Success Is Fragile - The Return Of Measles Is Proof

When I was a medical resident in South India in the 1990s, I rarely saw kids with measles. And I did not see much of polio or diphtheria or whooping cough either. None of this was a matter of luck. It was because childhood vaccination coverage in that region of India was high, and vaccines were highly effective in preventing these deadly childhood killers. Sadly, globally, childhood vaccination coverage is dropping, in part due to the health system disruptions caused by Covid-19 pandemic, and also because of increase in vaccine hesitancy. About 22 million children missed their measles vaccination in 2023. As a consequence, measles cases surged worldwide, infecting 10.3 million people in 2023, a 20% increase from 2022.

In his timely new book “Booster Shots: The Urgent Lessons of Measles and the Uncertain Future of Children's Health,” Adam Ratner, MD, MPH, a professor of pediatrics and microbiology at NYU Grossman School of Medicine, traces the history of measles, its impact on child health, the spectacular success of vaccination campaigns, and the emerging threats to this success story.

Madhukar Pai: The timing of your book on measles could not be more relevant, with the inauguration of President Trump, and his choice of anti-vaccine activist Robert F. Kennedy Jr. to lead the nation's biggest health agency. Several new books have documented the alarming rise of disinformation and anti-science. In this context, tell us a bit about the importance of your book and its biggest messages.

Adam Ratner: We have come to a place where political polarization is having direct negative effects on children’s health. This was true before the most recent election, and it was true – though to a substantially lesser extent – even before the COVID-19 pandemic. The pandemic accelerated and accentuated our divisions, and people focused their anger and frustration on public health measures, including vaccines, and on the messengers. As a result, we are now faced with a much worse scenario, in which even routine vaccination is under threat.

Vaccines represent one of humanity’s greatest achievements – they allow us to prevent death and suffering from a host of diseases that were major causes of childhood death not that long ago. The measles vaccine alone has saved more than 60 million lives – mostly children’s lives – over the past 25 years. The most important message of my book is that those sorts of achievements are not guaranteed. Public health successes can be fragile. Politics, education, trust in science – these things all matter, and with the fraying of trust that is unfolding in front of us, we risk losing that hard-won progress.

Madhukar Pai: In your book, you explain how measles infects humans, how extraordinarily infectious the virus is, and the immune amnesia it causes. Because many parents today have not seen the deadly consequences of measles, they think it is a mild cold. Why do we need to take measles seriously?

Adam Ratner: Before the measles vaccine became available in 1963, nearly everyone had measles at some point during childhood. It is, quite literally, the most contagious virus known, so there was really no escaping it. In high-income nations like the United States and Canada, most children and families experienced measles as an inconvenience – a week or so of fever and rash, followed by a complete recovery. Even in those countries, though, measles caused tens of thousands of hospitalizations and hundreds of deaths every year. These numbers were low enough that most people could still think of measles as just another childhood illness, but every year there were families that were shattered as a result of measles.

Measles infection also induces a kind of immune amnesia, literally erasing our immune system’s memory and increasing the odds of acquiring other serious infections for several years afterwards. As a result, measles vaccination provides two kinds of benefits – protection against the short-term risks of measles as well as prevention of the longer-term danger of measles-induced immune amnesia. Because measles is so contagious, we get the best protection when a very high proportion of the population (more than 95%) is vaccinated. Because very young children and some immunocompromised people can’t get the measles vaccine, it is even more important for all of the rest of us to get vaccinated.

WHO's Science in 5 - Measles: A growing threat

Madhukar Pai: In your book, you write, ‘measles preys on the weak, the crowded, the malnourished.’ Can you please explain the relevance of this and how it also translates into information that can be used to limit the damage measles can cause?

Adam Ratner: Across the world and across centuries, the burden of measles falls on those with the least resources. In the absence of vaccination or prior infection, all humans are susceptible to measles infection, but the outcome of that infection can depend on a much wider range of socioeconomic factors. One of the best examples is nutrition. We know that children with vitamin A deficiency are at substantially higher risk of death from measles than those who are not deficient. Providing vitamin A supplementation and, on a larger scale, ensuring adequate nutrition overall, decreases the risk of death from measles and many other infections. Likewise, overcrowded living conditions lead to children having increased exposure to measles at an earlier age – another factor that increases the risk of severe or fatal infection. Preventing measles through vaccination is the most important way to limit its toll, but understanding which kids are at highest risk and how we might be able to mitigate the impact of a host of infections beyond measles by targeting social and economic inequities is empowering in a different way.

Madhukar Pai: By 2000 the US had successfully eliminated measles. So what happened after 2000? Why are there so many measles cases and outbreaks today? What went wrong?

Adam Ratner: Thanks to expanded measles vaccine coverage, we were able to eliminate measles from the US in 2000. Some of the reasons that we are still dealing with measles today are (1) elimination is not the same as eradication. Elimination of a disease from a specific area at a specific time is a huge accomplishment, but it is a state that requires constant vigilance and maintenance of high vaccination levels. Travel-associated cases can still occur, and if vaccination levels drop, elimination is threatened. (2) There was an underestimation of the growing threat of the anti-vaccine movement. This threat has grown significantly, and we have seen alarming decreases in childhood vaccination rates, particularly in recent years.

Madhukar Pai: The Covid-19 pandemic has dented public confidence in vaccines, in public health, and in science itself. As a pediatrician and vaccine expert, how do you tackle vaccine hesitancy among parents?

Adam Ratner: There is no easy answer to this question, and addressing vaccine hesitancy or frank anti-vaccine attitudes has to happen at multiple levels – from individual families, to local communities, to regional or national policy. Pediatricians remain trusted advisors for parents, and as I discuss in the book, it is important for us to have these discussions carefully, with empathy, but clearly. It is crucial to make sure that parents have the information that they need and a strong and well-explained recommendation from their child’s pediatrician. At the level of communities and even governments, we need calm, science-based voices to explain the role of vaccination in keeping kids healthy and to counteract the continuous onslaught of misinformation and even disinformation that comes from an increasingly sophisticated and well-funded anti-vaccine movement.

Madhukar Pai: Globally, childhood vaccination coverage rates have dropped during the Covid-19 pandemic, and there is resurgence of whooping cough and polio as well. This is a massive challenge for global health. What lessons can we learn from measles, that we can apply to this problem?

Adam Ratner: The erosion of vaccine confidence has both short- and long-term impacts, neither of them good for children. In the short term, delaying or declining vaccines for individual kids puts them at risk for serious infections. We are already seeing increasing numbers of vaccine-preventable diseases. Because it is so contagious, measles clusters are often a bellwether for falling vaccine rates and loss of trust in public health systems. Pertussis (whooping cough) is another important vaccine-preventable disease, and we should also remember that we have vaccines to reduce the risk of influenza and COVID-19. Both of those vaccines provide considerable protection against hospitalization and death. Last year we had more than 200 deaths from influenza in children in the US, yet less than half of eligible kids get vaccinated. Bringing attention to these issues and trying to stem the erosion of public health systems are going to be crucial goals in the coming years – if vaccination rates continue to fall, we will see more frequent, more sustained outbreaks of preventable diseases.

Madhukar Pai: In your book, you talk about how measles thrives when we forget. And you recommend that we need ‘booster shots’ (title of your book) to bring back the memory. Please explain this for us.

Adam Ratner: Vaccines are medical marvels – they can protect children and adults from serious diseases – but the absence of disease doesn’t look like much. It just looks like regular life. You never get to know which kids were protected from meningitis or pneumonia or whooping cough. Vaccines are masters at making nothing happen. The problem is that, as we have seen with measles and polio, as time passes, generations of parents (and even doctors) come along who have never seen or even heard of these diseases, and people begin to question why pediatricians are advocating that they vaccinate against infections that are rare. The answer, of course, is that the diseases are rare because of vaccination and that if we stop vaccinating, in many cases, these diseases will return. This is a sort of “societal amnesia” that is analogous to the way that measles infection can specifically target the memory cells of a person’s immune system, causing them to become susceptible to diseases that they have encountered in the past – a situation called “immune amnesia”.

Just like a booster shot of a vaccine can remind your immune system how to fight off a microbe when your immunity is waning, we need to communicate about our past public health successes, recognize and own up to when we have fallen short, and engage with parents, community leaders, and policymakers. We need to make sure that we don’t lose our collective understanding of how important vaccination and other aspects of public health are for children. If we don’t succeed at this, the consequences for kids may be dire.