Monday, July 25, 2011
Vaccinations Should Not Be Mandatory
In a recent article for Big Think, David Ropeik argues that the risk posed by unvaccinated people is sufficient to justify coercing them into vaccinating. Measles is a potentially deadly disease and outbreaks are occurring due to declining vaccination rates, he reasons. "What does society do when one person’s behavior puts the greater community at risk? [...] We make them stop." I suppose it depends on the behavior and the degree of risk, but where vaccination is concerned, I disagree that coercive measures are warranted. While measles is not a fun disease and it can kill people, the sacrifice of individual autonomy isn't justified in this case.
The risk of getting the measles in the US is very low.
Between 2001 and 2010, the US saw 692 cases. 292 of these were imported by travelers who caught the disease in another country. Since you can't blame your unvaccinated compatriots if you catch the measles in another country, we'll exclude these. That leaves 400 cases in 10 years out of approximately 297 million people. The odds of getting the measles in the US in a typical year are thus 0.13 in a million. Given that about 10% of the population is unvaccinated, the odds of an unvaccinated person getting the disease are about 1.3 in a million.1 Note that the odds are higher for the unvaccinated, but 1.3 in a million is still extremely rare.
Of course, the risk is undoubtedly higher this year since there were over 150 cases reported by the end of June. However, the majority of these were foreign visitors and US residents who caught the disease abroad. Assuming half of these cases were acquired in the US and that current trends continue until year end, we could expect the odds of an unvaccinated person getting the measles this year to be about 4.9 in a million (150 in 30.9 million). These are pretty slim odds, measly even.
People often argue that it isn’t those who refuse vaccination they’re worried about, but those who are too young to be vaccinated, typically those under a year of age. About 15% of measles cases reported in the first half of this year affected children in this age group. This could end up being as many as 23 infants by year end (again using 150 as an estimate for the year total). So the chances of a child under age one getting the measles this year would be about 5.3 in a million.2 To put this risk in perspective, these odds are about the same as the odds of dying from a fall down the stairs (5 in a million).3 Odds of dying from the measles are less than 1 in 1000 cases. So the odds of an infant getting the measles in the US and dying as a result are about 5.3 in a billion. Panic is not in order.
The risk associated with vaccines is also incredibly small but it merits consideration if you think a 5 in a million chance of getting the measles warrants losing sleep. The rate of anaphylaxis (a serious allergic reaction) following MMR vaccination was estimated from VAERS reports at 1.8 in a million. With current levels of immunization coverage, the risk of a serious allergic reaction to a vaccine is comparable to the risk of an unvaccinated person getting measles in a typical year. However, it's worth keeping in mind that it’s because 90% of the population is vaccinated that the risk of getting measles is as low as it is. If a bunch of people reason “well, the chances are slim that I’ll get the disease so I’ll skip the vaccine” the chances of getting the disease will climb. With this in mind, a 1.8 chance in a million of anaphylaxis is worth taking. Of course there are other adverse events associated with the MMR vaccine, like fever, but these are minor and transient. (If there were convincing evidence of a link between autism and vaccines I’d discuss it here but I haven't found any).
Given the recent resurgence of vaccine-preventable diseases, people might understandably assume that vaccination rates have dropped and that forcing vaccine refusers to vaccinate will solve the problem. This doesn't seem to be the case.
Vaccination rates aren't declining
Ropeik argues: “The evidence is overwhelming that declining vaccination rates are contributing to outbreaks of disease. Take just one example, measles. The WHO reports outbreaks in many countries where vaccination rates have gone down: As of June - France (12,699 cases in 2011, more than in all of 2010 already, including six deaths), Spain (2,261), Italy (1,500), Germany (1,193, one death), Switzerland (580), Romania, Belgium, Denmark, and Turkey.” Based on WHO data, however, the rates of vaccination with “measles containing vaccine” do not appear to be declining (see chart below).
*2005 and 2006 data for France were not available.
While vaccination in many countries may be below desired levels, globally, childhood immunization is higher than ever. Despite the prevalence of anti-vaccination sentiments and misinformation in the media (on both sides of the debate), vaccination rates in the US is not declining either (see chart below).
*Based on CDC data for 19- to 35-month-olds. The 2010 value used is an estimate based on data provided for July 09 to June 10. Data was not available for 3+DTP (3 doses or more) for 2005-2008.
Between 2008 and 2009, there was a noticeable dip in MMR uptake, but this is unlikely to have had a sudden or dramatic effect on overall coverage, since fluctuations in this age group would be buffered by the rest of the population. Despite minor fluctuations, vaccination coverage in the US is relatively high and stable. The CDC agrees. As Anne Schuchat, director of CDC's National Center for Immunization and Respiratory Diseases, notes "Nearly all parents are choosing to have their children protected against dangerous childhood diseases through vaccination."
Coercive measures may not work
In light of the recent resurgence of vaccine-preventable diseases, it would be a good time for vaccine refusers to rethink vaccination and for vaccine accepters to get a booster. It would also be a good idea for travelers to other countries to make sure their immunizations are up to date. It isn’t clear, however, how much of an effect coercive measures to boost already-high vaccination rates in the US would have on outbreaks. In France, where MMR vaccination is compulsory for pre-school children, coverage is only at 85%.
Ropeik suggests that we might place restrictions on the community/social facilities that unvaccinated people may use. There's reason to believe that this may be counterproductive. Despite overall high, stable vaccination rates, rates have declined in some areas resulting in pockets or clusters of susceptible people. If certain schools or facilities have a high proportion of susceptible members, a single infected person could result in a large outbreak, with contagious people subsequently dispersing throughout the community and infecting others. Restricting the unvaccinated to a smaller selection of schools or facilities would concentrate susceptible people in these places. If the clustering of unvaccinated people is an important factor in disease transmission, policies that promote it are ill-advised.
Increased vaccination may not save money
Ropeik points out that “[One] outbreak cost two local hospitals a total of nearly $800,000, and the state and local health departments tens of thousands more, to track down the cases, quarantine and treat the sick, and notify the thousands of people who might have been exposed." The cost of managing outbreaks, however, serves as poor justification for coercive measures, since the cost of vaccinating the remaining 10% of the population would be at least $1.2 billion ($20/dose x 2 doses x 30.9 million); $800, 000 is chump change. It might not be worthwhile financially to vaccinate a population beyond what’s considered ample to establish herd immunity. Of course, cost isn’t always a great guide when it comes to ethical decision-making since not all things of value come with price tags. What value would we assign to a human life? Autonomy, too, has value.
To sum up, coercive measures aren't indicated because the risk posed by measles is low, a high proportion of the population is vaccinated and continue to vaccinate their children voluntarily, coercive measures may be counterproductive, and autonomy is valued by many people.
I wholeheartedly endorse vaccination, at least where dangerous diseases are concerned and the vaccines have a long track record of being relatively safe and effective. For polio, measles, and pertussis, I think everyone who can be vaccinated should be. What I oppose is the unjustified denial of people’s right to make their own informed decisions. I’d like to live in a society with 99% immunization coverage, but an 8 or 9% increase with a slight reduction in an already-low risk isn’t worth a sacrifice of others' autonomy.
1 This assumes that all 40 measles cases per year affect unvaccinated people which is actually not the case, so this estimate is high.
3 This statistic is attributed to the National Safety Council; I found it in Discovery Channel's shark week quiz. Give it a try.
photo credit: Wikimedia Commons
*Correction/clarification: I previously stated that Ropeik’s piece was titled “Should Vaccination Be Mandatory?”. I subscribe to Big Think’s newsletter and Ropeik’s article had been delivered to my inbox with this heading, so I mistakenly thought it was the title. This correction has now been made in my post. Regrettably, I also titled my post in response to this question and I think the term “mandatory” is confusing here. By mandatory, I mean that exemptions for philosophical and/or religious reasons wouldn’t be allowed, as they generally are. Ropeik seems to be arguing for coercive measures beyond policies that are currently in place and this is where my disagreement lies.
Posted by Quinn O'Neill at 12:50 AM | Permalink