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PoAC: Anatomy of an Epidemic
May. 4th, 2006 04:59 amThis is a work in progress, people. Please, if there's an area of this that I've made a mistake on, let me know about it. I'm not a scientist, just a well-read and concerned parent.
1) Public Health officials and medical researchers identify a disease that could be prevented with a vaccine. They develop the vaccine for this common ailment which we'll call Disease A, and advise parents to vaccinate their children. Since most parents know of at least one person who suffered complications from Disease A, and since they all know about the weeks of misery it causes even without the complications, the vast majority of parents agree to the vaccinations. All children receive it, either at school or at checkups, and it is added to the roster for babies to receive on a certain schedule. Within twenty years, most people under 30 are vaccinated against Diesease A. Incidence drops dramatically.
2) The people who were first vaccinated are now becoming parents. Most have never seen the nasty complications that are possible with Disease A; in fact, many have never seen a case of Disease A at all. However, their parents have, as have their doctors. Most people continue to vaccinate, but a few neglect their vaccines, mostly without a conscious choice; they just don't make it to see their doctor at the right time, and because the public health push is over and Disease A is off the radar, most doctors don't follow up on missed vaccinations. However, incidence does not rise much because most of the population at this point is protected from it. The unprotected grow up in blissful ignorance of the nastiness they've missed, and their parents, if they think about it at all, don't really worry. No one gets Disease A nowadays.
3) Something happens to damage the public's trust in the vaccine. Perhaps one study links the vaccine with a developmental problem. Perhaps one ingredient is found to be a possible carcinogen in large doses. Perhaps a few people come down with a mild form of Disease A, from getting the vaccine. Whatever happens, a small portion of the population begins to see the vaccine as more dangerous than the disease. They read up on the symptoms of the disease, but they skip the section about complications; those only happen in one or two percent of cases, or they only happen to the elderly/immuno-deficient, etc, etc, so it doesn't apply to their children. Having seen very few cases of this disease in their lifetimes, these parents decide that the vaccination is a bigger risk than the disease itself, and they choose not to vaccinate. There is now a substantial segment of the population that is not getting vaccinated, either due to parental choice or parental neglect of well-child doctor's visits. Slowly, incidence starts to rise.
4) Incidence is rising because more people are unprotected from disease A than a few years before, including people of every age group. Adults have neglected their booster shots - or doctors have not offered them - so the immunity they had as children is weakening. Those who were among the first generation of parents to vaccinate are now elderly, and their immune systems may be compromised by age or illness. Children are also growing up without immunity - enough of them to create the possibility of a school-level outbreak. Still, though, it has not risen to the point where there are many cases of complications. While many people now know someone who has recently had Disease A, few know someone who was part of the 1% complication rate, and practically nobody knows someone who has recently died of the disease. Parents who are worried about the vaccine continue to see the vaccine as more dangerous than a common childhood ailment that they've still rarely seen in action. Public Health officials ask that parents vaccinate, but they do not enforce. Everyone has the right to decide on health care for their children, after all.
5)By this point, the level of protection available to most of society has dropped significantly. Large numbers of people are not adequately vaccinated against Disease A. Suddenly, or perhaps gradually depending on the disease, there is a huge outbreak. Maybe it begins with an outbreak in another country, brought by travellers who didn't realize they had it. Maybe it begins with bacteria or a virus in sewage and there's a break in the treatment process that causes the disease to be widely spread through tap water or public places like pools. In any case, those who are not protected start getting sick. Some of them don't get very sick. They have mild cases, or they carry the disease with no illness at all. Some people who have been vaccinated also get sick, for several reasons. Perhaps they were very run-down when they came in contact with Disease A, and their body couldn't fight it off. Perhaps they were one of the 1% of the population for whom the vaccine never created an immunity. Perhaps it has worn off over a long period of time. In any case, people realize that the vaccine isn't protecting them as well as they thought it was. Because there are now significantly more cases, people are starting to see and know the 1% of people who suffer complications from Disease A. They're now getting concerned, but their trust in the vaccine has diminished to the point where they don't think it will help. After all, lots of people are getting sick in spite of the vaccine, and there was all that stuff about how the vaccine can produce X side effect, and there's no smoke without some fire, right? These people decide not to vaccinate, or to hold off on their vaccinations for their children until a different, safer version of the vaccine comes on the market. Unfortunately, getting this safer version takes time, and meanwhile, their kids are part of the growing percentage of the population who are at risk of catching Disease A.
6) At this point, less than half the population has adequate protection. Outbreaks are common. Then the disease in question does something unexpected: it mutates. It has come across so many people who were immune to it that it has figured out how to get around the protections offered by the vaccine. In all likelihood, the people who are vaccinated are still receiving some protection, but it's no longer enough to keep most of them from getting at least mildly ill. Medical researchers scramble to come up with a new vaccine for this knew strain of the virus or bacteria. It takes a while. People get sick. In some areas, where rates of vaccinations were especially low, hospitals are overwhelmed by the number of acute cases. People start to die of complications, because there aren't enough beds to take proper care of them in the hospital. Others, seeing this, distrust the medical system even more. They keep their families away from hospitals, but not necessarily out of the public sphere. Many of these people are still spreading the disease, either because they are mildly sick or because they are carriers who never got sick in the first place.
7) The new vaccine is ready. Health officials advise everyone, vaccinated or not, to get the new vaccine. Most do, because they've seen, now, what happens when this disease runs rampant in the population. Some don't, because their fears of the old vaccine have carried over to the new one, or because they figure they have immunity from this since they came down with it. This time, not quite everyone gets immunity because not as many people are prepared to trust the vaccine. Without that complete level of societal protection, there is still the occasional outbreak. The cycle will start again, but sooner this time due to a higher number of vulnerable people in the population and a higher level of distrust of the vaccines. They told us the last vaccine would protect us, and look where that landed us - Aunt Mary died of it, on a guerney in a hospital corridor!
8) The spillover from the recurrence of Disease A, affects the rate of vaccination for other vaccines. Even though the ingredients are different (either because they've been changed or because they were different to start with) people still mistrust all vaccines. The chances of a deadly outbreak of a different disease have increased because fewer people are choosing to vaccinate their children.
Prevention of this cycle is actually really simple: ensure an adequate level of protection before the first new outbreak. Make sure that booster shots are available to adults. Make sure that parents understand the possible complications, not just for their own kids but for others who may contract this disease through contact with their children. Work constantly to improve the safety of vaccines, hopefully before the public becomes aware that there was a potential problem with them. Make sure that the people reporting on scientific findings for non-scientists actually know what they are talking about and how statistics work in science, so that they can present risks as they actually are, and not in some journalist's view of a "balanced" report.
Mumps and whooping cough are already at the stage where outbreaks are taking hold in the population. In some parts of the world, polio is making a comeback due to the cessation of vaccination programs in Nigeria and other countries (a cessation which has a lot to do with government scare tactics and inter-religious conflict.) Hepititus B and HPV might never get as far as widespread immunity due to general mistrust of the vaccines and the stigma associated with these diseases, perceived to be STD's. And every person who remains unvaccinated is one more in the link to death for someone else.
1) Public Health officials and medical researchers identify a disease that could be prevented with a vaccine. They develop the vaccine for this common ailment which we'll call Disease A, and advise parents to vaccinate their children. Since most parents know of at least one person who suffered complications from Disease A, and since they all know about the weeks of misery it causes even without the complications, the vast majority of parents agree to the vaccinations. All children receive it, either at school or at checkups, and it is added to the roster for babies to receive on a certain schedule. Within twenty years, most people under 30 are vaccinated against Diesease A. Incidence drops dramatically.
2) The people who were first vaccinated are now becoming parents. Most have never seen the nasty complications that are possible with Disease A; in fact, many have never seen a case of Disease A at all. However, their parents have, as have their doctors. Most people continue to vaccinate, but a few neglect their vaccines, mostly without a conscious choice; they just don't make it to see their doctor at the right time, and because the public health push is over and Disease A is off the radar, most doctors don't follow up on missed vaccinations. However, incidence does not rise much because most of the population at this point is protected from it. The unprotected grow up in blissful ignorance of the nastiness they've missed, and their parents, if they think about it at all, don't really worry. No one gets Disease A nowadays.
3) Something happens to damage the public's trust in the vaccine. Perhaps one study links the vaccine with a developmental problem. Perhaps one ingredient is found to be a possible carcinogen in large doses. Perhaps a few people come down with a mild form of Disease A, from getting the vaccine. Whatever happens, a small portion of the population begins to see the vaccine as more dangerous than the disease. They read up on the symptoms of the disease, but they skip the section about complications; those only happen in one or two percent of cases, or they only happen to the elderly/immuno-deficient, etc, etc, so it doesn't apply to their children. Having seen very few cases of this disease in their lifetimes, these parents decide that the vaccination is a bigger risk than the disease itself, and they choose not to vaccinate. There is now a substantial segment of the population that is not getting vaccinated, either due to parental choice or parental neglect of well-child doctor's visits. Slowly, incidence starts to rise.
4) Incidence is rising because more people are unprotected from disease A than a few years before, including people of every age group. Adults have neglected their booster shots - or doctors have not offered them - so the immunity they had as children is weakening. Those who were among the first generation of parents to vaccinate are now elderly, and their immune systems may be compromised by age or illness. Children are also growing up without immunity - enough of them to create the possibility of a school-level outbreak. Still, though, it has not risen to the point where there are many cases of complications. While many people now know someone who has recently had Disease A, few know someone who was part of the 1% complication rate, and practically nobody knows someone who has recently died of the disease. Parents who are worried about the vaccine continue to see the vaccine as more dangerous than a common childhood ailment that they've still rarely seen in action. Public Health officials ask that parents vaccinate, but they do not enforce. Everyone has the right to decide on health care for their children, after all.
5)By this point, the level of protection available to most of society has dropped significantly. Large numbers of people are not adequately vaccinated against Disease A. Suddenly, or perhaps gradually depending on the disease, there is a huge outbreak. Maybe it begins with an outbreak in another country, brought by travellers who didn't realize they had it. Maybe it begins with bacteria or a virus in sewage and there's a break in the treatment process that causes the disease to be widely spread through tap water or public places like pools. In any case, those who are not protected start getting sick. Some of them don't get very sick. They have mild cases, or they carry the disease with no illness at all. Some people who have been vaccinated also get sick, for several reasons. Perhaps they were very run-down when they came in contact with Disease A, and their body couldn't fight it off. Perhaps they were one of the 1% of the population for whom the vaccine never created an immunity. Perhaps it has worn off over a long period of time. In any case, people realize that the vaccine isn't protecting them as well as they thought it was. Because there are now significantly more cases, people are starting to see and know the 1% of people who suffer complications from Disease A. They're now getting concerned, but their trust in the vaccine has diminished to the point where they don't think it will help. After all, lots of people are getting sick in spite of the vaccine, and there was all that stuff about how the vaccine can produce X side effect, and there's no smoke without some fire, right? These people decide not to vaccinate, or to hold off on their vaccinations for their children until a different, safer version of the vaccine comes on the market. Unfortunately, getting this safer version takes time, and meanwhile, their kids are part of the growing percentage of the population who are at risk of catching Disease A.
6) At this point, less than half the population has adequate protection. Outbreaks are common. Then the disease in question does something unexpected: it mutates. It has come across so many people who were immune to it that it has figured out how to get around the protections offered by the vaccine. In all likelihood, the people who are vaccinated are still receiving some protection, but it's no longer enough to keep most of them from getting at least mildly ill. Medical researchers scramble to come up with a new vaccine for this knew strain of the virus or bacteria. It takes a while. People get sick. In some areas, where rates of vaccinations were especially low, hospitals are overwhelmed by the number of acute cases. People start to die of complications, because there aren't enough beds to take proper care of them in the hospital. Others, seeing this, distrust the medical system even more. They keep their families away from hospitals, but not necessarily out of the public sphere. Many of these people are still spreading the disease, either because they are mildly sick or because they are carriers who never got sick in the first place.
7) The new vaccine is ready. Health officials advise everyone, vaccinated or not, to get the new vaccine. Most do, because they've seen, now, what happens when this disease runs rampant in the population. Some don't, because their fears of the old vaccine have carried over to the new one, or because they figure they have immunity from this since they came down with it. This time, not quite everyone gets immunity because not as many people are prepared to trust the vaccine. Without that complete level of societal protection, there is still the occasional outbreak. The cycle will start again, but sooner this time due to a higher number of vulnerable people in the population and a higher level of distrust of the vaccines. They told us the last vaccine would protect us, and look where that landed us - Aunt Mary died of it, on a guerney in a hospital corridor!
8) The spillover from the recurrence of Disease A, affects the rate of vaccination for other vaccines. Even though the ingredients are different (either because they've been changed or because they were different to start with) people still mistrust all vaccines. The chances of a deadly outbreak of a different disease have increased because fewer people are choosing to vaccinate their children.
Prevention of this cycle is actually really simple: ensure an adequate level of protection before the first new outbreak. Make sure that booster shots are available to adults. Make sure that parents understand the possible complications, not just for their own kids but for others who may contract this disease through contact with their children. Work constantly to improve the safety of vaccines, hopefully before the public becomes aware that there was a potential problem with them. Make sure that the people reporting on scientific findings for non-scientists actually know what they are talking about and how statistics work in science, so that they can present risks as they actually are, and not in some journalist's view of a "balanced" report.
Mumps and whooping cough are already at the stage where outbreaks are taking hold in the population. In some parts of the world, polio is making a comeback due to the cessation of vaccination programs in Nigeria and other countries (a cessation which has a lot to do with government scare tactics and inter-religious conflict.) Hepititus B and HPV might never get as far as widespread immunity due to general mistrust of the vaccines and the stigma associated with these diseases, perceived to be STD's. And every person who remains unvaccinated is one more in the link to death for someone else.