 I'm Salvatore Bobonis and this week's global social problem of the week is public resistance to immunization. Nothing better illustrates the fact that all people share in a single biological society than the epidemiology of immunization. Obviously, we all share each other's germs, which are spread through breathing, touching, kissing, and myriad other ways. As a result, one person's immunization from germs is another person's immunization from the same germs. When I immunize me, I immunize you. But in many countries today, public resistance to immunization puts the benefits of this so-called herd immunity at risk. Look, in most developed countries today, it's perfectly safe to walk barefoot in public parks. At least safe from communicable diseases. You might stub your toe. You might get mugged by a criminal. But you are not going to catch tapeworm parasites that bore into your feet from contact with parasites in the soil, infect your blood and make their way to your intestines where they hook on and grow inside your intestines. It's also safe to roll around on the grass and then touch your hands, your lips without having to worry that you're going to contract cholera from bacteria in the soil. There are diseases you can catch from soil, but you're not going to catch common communicable diseases. And the reason is that nobody around you in society has those diseases. If there's no one to catch them from, you can't catch the disease. It's relatively safe to drink from public water fountains, to sit on public toilet seats, even to kiss complete strangers. In general, it's simply safe to go out in public without wearing a mask and rubber gloves because the other people who are there out in public don't have diseases you can catch from them. Well, it's also relatively safe to go without immunization from serious diseases, as long as most of the other people around you in society are immunized for you. This is known as herd immunity. Heard immunity arises because a disease cannot spread in a population unless there are susceptible people for it to spread to. Even if one person gets the disease, if that person is surrounded by dozens of people who are all immunized, that disease won't spread from that one person. So if I live in New York and a disease enters United States in San Francisco, even if I'm not immunized in New York, the 300 million immunized people between me and San Francisco will prevent that disease from spreading from San Francisco to me in New York. It doesn't take 300 million immunized people. In fact, the immunization of even a portion of the population can break the chain of transmission of disease from an infected person to a person who might not be immunized. Now the effectiveness of this herd immunity depends on how infectious the disease is. Measles, which is extraordinarily infectious, requires an immunization rate of 90 or 95 percent of the population to prevent a full-blown epidemic, to prevent transmission, continued transmission throughout the population. Other diseases are not quite so communicable. So the common flu requires something like 50 percent immunization. As long as 50 percent of the population is immunized against the particular strain of flu that happens to hit, everybody else is more or less safe from the flu because the flu won't spread throughout the population if half the population have been immunized. Herd immunity is less a public good that is susceptible to free riding. A public good is a benefit of some kind that cannot be limited or kept private. It's something that you can't keep to yourself. If you immunize yourself from a disease, you immunize other people. You can't just keep the benefits of immunization to yourself. You share those benefits with other people. Unfortunately, public goods are susceptible to free riding. Free riding is taking advantage of public goods provided by others. So when you don't immunize, but you live in a population that is largely immunized against a disease, you're free riding on the immunization on the public good provided by other people. In other words, herd immunity sets up a classic tragedy of the commons in which people prioritize their needs over the needs of the community. The tragedy of the commons arises from 18th century England where common land held in common by a village in which every villager had the right to graze his or her cattle on the common land. Common land tended to become highly degraded. There was no grass on the common land because any time a single blade of grass appeared, everyone wanted to graze their cattle on the common land. Nobody wanted to have to use their own land to graze cattle. The tragedy of the commons is that if you have land held in common that everybody can share, it gets overused and as a result is available to no one. Other classic tragedies of the commons are fish in the ocean which have been so overfished that the world's oceans today are largely devoid of large fish. There just aren't fish in the ocean because of the tragedy of the commons and the ultimate tragedy of the commons perhaps being global warming. Well herd immunity is also a tragedy of the commons. It's inconvenient to get immunized for diseases. It may be costly in some places you have to pay to be immunized although usually governments subsidize vaccination at least in developed countries and it may even be dangerous to get immunized. I mean all vaccines carry some risk of adverse reaction. Every year some people die as a result of some kind of allergic reaction to the immunization itself. So there is some risk or inconvenience of getting immunized. There's certainly an incentive not to immunize whether through laziness or through fear and as a result there are people who don't immunize. Vaccination is focused especially on the measles, bumps, rubella, the MMR vaccine because many activists allege that it causes autism. Some activists argue that it's not the MMR vaccine itself that causes autism but that the large number of vaccines given to infants together cause autism and that MMR as a combined vaccine is part of that confluence of vaccines that's causing autism. Now I'm a sociologist, I'm not a biologist or an epidemiologist or a medical doctor. I can't form a judgment on whether vaccines cause autism but I want to be very clear that the community of professional epidemiologists is absolutely united in the conclusion that vaccines are not linked to autism. Now many people view vaccination as an individual choice but when too many people choose not to vaccinate their children, herd immunity suffers. Obviously this affects the people who neglected to immunize against the disease so people who are negligent, uninformed, too poor and even if immunizations are free people can still be too poor to take a day off work to take their children to get vaccinated. There are also children of parents who refuse to immunize them to get them vaccinated. So the lack of herd immunity or the lack of immunization is not a decision that children make yet it's something that puts children at risk, parents putting their own children at risk. Well we might say that that's your own problem. If you want to take the risk of the disease or if you want to put your child at risk of the disease that's your own business. After all we all face risks every day and parents every day have to make decisions about what's good or bad for their children. But less obviously the decision not to vaccinate affects people who are unable to immunize themselves against the disease. So people who are under immunosuppressive therapy like cancer patients, people with AIDS and other immune disorders and probably the most photogenic group of people who are at risk of disease, babies who are too young to be vaccinated. So babies under one year of age who have not received the vaccine but can still get the disease. Newborn babies rely on herd immunity to protect them from the disease because they don't have sufficient immunity themselves against the disease. Also when you put all this together it's just bad public health. I mean getting beyond the cost benefit analysis and the morality and thinking about all of these kind of you know big moral and scientific issues it's just unprofessional. Vaccination is a cornerstone of public health and vaccinating our children is certainly good public health. And here's the evidence. I mean in the United States vaccination especially for measles has become very controversial. Many people believe that measles vaccination is the root of the autism epidemic spreading or that has emerged in the country in the last 15 or 20 years. And so parents especially relatively well off parents, well informed parents are choosing not to vaccinate against measles. Their argument is often that well measles isn't around I've never even seen anyone with measles the disease is long since gone and so they don't bother to vaccinate. Well in January 2015 an outbreak of measles occurred at Disneyland in Southern California in Anaheim. It's suspected though not proven that the initial case came from the Philippines the strain of measles that spread around the US in 2015 was a strain that is common in the Philippines of course people from all around the world go to Disneyland and non-immunized non-vaccinated children came into contact with this child unknown child in Disneyland 92 children came down with measles in California and then a scattering of children from the rest of the country. Now these weren't all children who'd gone to Disneyland these were both the small the initial group of children who'd caught the disease at Disneyland who then spread it to their non-vaccinated classmates and friends who then spread it further and spread it further. As with any tragedy of the commons immunization can be promoted via education but must be enforced via government I mean just think about climate change it's all great that we educate people to turn off their lights when they leave the room or to you know buy more fuel efficient automobiles but that's simply not sufficient to make sure that we solve the problem of global warming. Voluntary targets simply don't work and in the same way with immunization voluntary immunization is not really enough governments have to insist on immunization and the number one way they do that is by requiring immunization in order for children to be able to attend public schools. Now of course research should continue into the safety of vaccines and the possibility of any link with autism or with other diseases that we may not yet have understood could be linked to vaccination but vaccination is so important for the public health that really can't be left up to individual discretion. Every individual must take the risk associated with vaccination in order for the rest of the population to be safe from disease. Unfortunately in the United States and other developed countries vaccination is coming to be seen as a matter of personal choice and personal freedom rather than a matter of public health. The attitude is very much I'm in charge of myself and my health not the government and of course this is linked to you know a neoliberal ideology that has originated in the United States and spread to much of the rest of the world that emphasizes individual responsibility for personal outcomes rather than public responsibility for national outcomes. We can see where this leads in countries like Pakistan and Nigeria religious authorities demand the freedom for families to refuse vaccination with dire consequences. This is a polio victim in Pakistan begging for charity on the roadside. Polio is a very real disease in Pakistan, Afghanistan, India, Nigeria, you know places where the world where it has not yet been eradicated. It doesn't exist in the West because we have been immunizing people for some 60 years now against polio. It's not that these diseases somehow simply won't come to the West. It's the fact that we immunize that we force people to immunize against diseases even diseases that haven't been seen in decades in order to prevent their reoccurrence. Thank you for listening. I'm Salvatore Bobonis. You can find out more about me at SalvatoreBobonis.com where you can also sign up for my monthly newsletter on global affairs.