I have written extensively about several whooping cough (Bordetella pertussis) outbreaks which had reached epidemic levels in areas like the Washington state, which had been considered one of the worst outbreaks in the USA during the past several decades. This whooping cough outbreak has lead to several deaths here in the USA and in other countries such as the UK.
Of course, these outbreaks and epidemics have lead to the “blame game” from the antivaccination cult, because they have claimed that since A) most kids are vaccinated, and B) we’re having this outbreak, then C) either the vaccines are useless or are actually the cause of the outbreak. Seriously. They blame the vaccines.
There have been numerous reports about a whooping cough outbreak in the Reno County, KS area, with about 70 cases of the disease being reported. The report indicates that most of the kids who have the disease were vaccinated. It is unclear who said this, and what are the actual statistics. But for now, we’ll take this at face value.
Since this outbreak will undoubtedly lead to the typical antivaccine rhetoric about the whooping cough vaccines, DTaP or Tdap (which also protect against tetanus and diphtheria), I decided to search the internet to find the most popular vaccine denialist arguments regarding pertussis vaccinations–then debunk them. Hopefully, this will be useful for those who are observing what’s going on in Reno.
Continue reading “Whooping cough outbreak – science and simple math”
Yesterday, Dorit Rubinstein Reiss explained why most experienced journalists ignore Robert F. Kennedy Jr’s views on vaccines. He gets simple facts about vaccines completely wrong again and again. She was referencing an interview Kennedy had given on Fox News – as a part of that interview, Kennedy misused a small study about the DTaP vaccine (for diphtheria, tetanus and pertussis, or whooping cough). Unfortunately, RFK Jr and vaccine safety of DTaP has continued – he has doubled down on misusing this study in an article by him published today.
I thought we would take a look at the issues specific to this new version of RFK Jr and vaccine safety – we’ll analyze his comments and then take a detailed look at the published article that forms the basis of Kennedy’s comments.
RFK Jr and vaccine safety – the article
RFK Jr’s article about vaccine safety was published in Collective Evolution, a pseudoscience-pushing website that has articles about the sun exploding soon and aliens circling the moon. No, I’m not joking, Kennedy thinks his outlandish claims about vaccines fit well next to an article about alien structures on the moon.
But let’s get to what he’s saying about the DTaP vaccine:
Now a team of Scandinavian scientists has conducted such a study and the results are alarming. That study, funded in part by the Danish government and lead by Dr. Soren Wengel Mogensen, was published in January in EBioMedicine. Mogensen and his team of scientists found that African children inoculated with the DTP (diphtheria, tetanus and pertussis) vaccine, during the early 1980s had a 5-10 times greater mortality than their unvaccinated peers.
In the primary analysis, DTP-vaccinated infants experienced mortalities five times greater than DTP-unvaccinated infants. Mortalities to vaccinated girls were 9.98 times those among females in the unvaccinated control group, while mortalities to vaccinated boys were 3.93 times the controls. Oddly, the scientists found that children receiving the oral polio vaccine simultaneously with DTP fared much better than children who did not. The OPV vaccine appeared to modify the negative effect of the DTP vaccine, reducing mortalities to 3.52 times those experienced among the control group. Overall, mortalities among vaccinated children were 10 times the control group when children received only the DTP.
The data suggest that, while the vaccine protects against infection from those three bacteria, it makes children more susceptible to dying from other causes.
If this were true, it would be one scary study. However, does this study actually make that claim? Stay tuned, we’ll get to it.
Kennedy, then, comes to this conclusion:
In 2014, The World Health Organization (WHO) Strategic Advisory Group of Experts on Immunization (SAGE) conducted its own literature review of the potential non-specific effects (NSEs) of several vaccines, including DTP, and found that the majority of studies reported a detrimental effect of DTP (Higgins et al., 2014; Strategic Advisory Group of Experts of Immunization, 2014) due to its penchant for increasing susceptibility to unrelated infections. SAGE recommended further research.
Moreover, Mogensen and his colleagues observe that the studies reviewed by SAGE probably underestimated the lethal effect of the DTP vaccine because of unusually high mortality in the control groups, ”Unvaccinated children in these studies have usually been frail children too sick or malnourished to get vaccinated and the studies may therefore have underestimated the negative effect of DTP”. The Mogensen study sought to avoid this pitfall by using controls selected by birthday and by eliminating underweight children and orphans from both the study group and the control group. It included only children who were breastfed. All the infants were healthy at the time of vaccination. Nevertheless, the Mogensen authors point out that, even in their study, the unvaccinated children had slightly worse nutritional status and travelled more – biases that would tend to increase mortality. They conclude that, “The estimate from the natural experiment may therefore still be conservative.”
In fact, this is what SAGE says about the pertussis vaccine (a component of DTP) safety (pdf):
Evidence supports a high degree of confidence in the estimate of the effect that incidence of serious adverse events following whole cell pertussis vaccination is low. From the reviewed articles, there is no significant risk of serious adverse events following administration of wP (see Note 1).
This is what SAGE says about the diphtheria component (pdf):
Diphtheria toxoid (see Note 2) is one of the safest vaccines available. Severe reactions are rare, and to date no anaphylactic reac- tions attributable to the diphtheria component have been described.
Finally, this is what SAGE says about the tetanus component (pdf):
Severe adverse events are extremely rare. TTCV using various presentations have demonstrated to be safe to use in immunocompetent individuals of various age and population groups including infants, children, adolescents, adults and pregnant women.
In other words, SAGE has never said that there’s a detrimental effect of the DTP (or DTaP) vaccine on children, adults, or anyone. In summary, SAGE has been very positive, with regards to vaccine safety and adverse events, not even close to the narrative pushed by Robert F Kennedy Jr.
But let’s take a look at this Danish study pushed by RFK Jr.
RFK Jr and vaccine safety – the study
The study, published in EBioMedicine, by Dr. Soren Wengel Mogensen et al. studied the mortality rate of children after vaccination with DTP from 1984-1987. The children received the vaccine during quarterly weigh-ins in Guinea, Africa. Here are some of the issues with the study:
- It was published in a rather obscure journal. This alone does not give us an indicator of the quality of the paper, but if we really had data that showed us there was a concern with the DTaP vaccine, an important part of the childhood vaccine schedule, it should have been published in a higher quality journal, maybe one that focuses on vaccines, such as the journal Vaccine. Generally, I have found that publishing in obscure journals results from not finding a place in a major journal, mostly as a result of the weakness of the data.
- The study looks at the mortality rate after the vaccine used at that time, which, as I mentioned, contained the whole-cell version of pertussis. That vaccine was pulled from the market and replaced with the acellular version. The reasons for changing the vaccines are complex, but it was partially because of the higher rate of minor adverse events with the wP version of the pertussis vaccine. On the other hand, there is no evidence that the wP version caused more deaths than the current aP version.
- The study only examined 1057 children, which is a tiny number in any epidemiological study that tries to compare one group to another to examine a potential effect. Many case control studies that examine vaccine effects (either effectiveness or adverse events) use 100,000 to several million patients.
- The number of deaths that was used in the study was tiny, sometimes only 1 death in a population group (like female unvaccinated children). Because they used such small numbers, unintentional bias could occur.
- The deaths were not categorized. Were they auto accidents, violence, or other mortality events that absolutely have nothing to do with vaccination. With such small numbers analyzed, it’s possible that unrelated mortality could have given results that could change dramatically with just a handful of unrelated deaths. Unless you can convince me that vehicle mortality is somehow related to vaccination status.
- Ironically, the study showed that there was decreased mortality with the children who received oral polio vaccine (separate from the DTP vaccine). If we accept this statistically suspect small sample as unbiased (which we can’t), the overall results are positive with a full vaccination. It kind of contradicts the RFK Jr and vaccine safety narrative.
It’s difficult for me to accept the viability of this study on just about any level. At best, at the very best, we can accept this study as an observational one which could, if not contradicted by better studies, form the basis of a hypothesis about the DTaP vaccine.
And that leads me to another critical point. Robert F Kennedy Jr cherry-picked a study that supports his beliefs about vaccine safety, the antithesis of real science (hence, Kennedy chose the pseudoscientific Collective Evolution for his article). If we look at larger studies more broadly, what can we say about the safety profile of the DTaP vaccine?
Here’s a Danish study that included over 805,000 children looking at various outcomes to getting multiple antigen vaccines, such as DTP or DTaP, came to this conclusion:
These results do not support the hypotheses that multiple-antigen vaccines or aggregated vaccine exposure increase the risk of nontargeted infectious disease hospitalization.
In plain speak, there is no data to support RFK Jr and vaccine safety issues – with respect to these vaccines, there was no difference in non-targeted (that is non-diphtheria, -pertussis or -tetanus) infections in the vaccinated vs. non vaccinated groups. This is much more robust data than the study upon which Kennedy relies for his belief set.
But there’s more. In a meta-review, considered the pinnacle of high quality scientific research hierarchy, which included over 183,000 participants in 58 different trials, the authors concluded that,
Acellular vaccines have fewer adverse effects than whole-cell vaccines for the primary series as well as for booster doses.
Thus, the authors found no vaccine related mortality for either vaccine, which completely and utterly contradicts Kennedy’s belief about the safety of the DTaP vaccine. If we’re going to cherry pick, let’s choose the studies that actually are well designed with good statistics and outcomes that can reject or accept a hypothesis. Kennedy’s study does neither.
Not only does RFK Jr use research that has no relevance to the modern DTaP vaccine, but also he relies on a weak, small, and poorly designed study. Furthermore, the study he uses is clearly of lower quality than other, more powerful and robust studies, which show that there is no mortality concerns with the vaccine.
Kennedy’s cherry picked study simply fails to provide us with any quality evidence that we should be concerned about the modern DTaP vaccine. None. Only in a world of pseudoscience, where a weak, one-off study has more value than better designed and populated studies, can we cherry pick bad evidence to dismiss one of the most useful vaccines in the armamentarium of diseases preventing weapons.
RFK Jr and vaccine safety? Yeah, he’s wrong. Badly wrong.
- wP, or whole cell pertussis vaccine, is no longer used in the USA. We use aP, or acellular pertussis, in our DTaP vaccine. At the time of the vaccination of the children in the study, the whole cell version was used.
- The diphtheria vaccine doesn’t protect directly against the bacterial infection but against the toxin produced by the diphtheria bacteria which causes the symptoms of the infection.
- Hviid A, Wohlfahrt J, Stellfeld M, Melbye M. Childhood vaccination and nontargeted infectious disease hospitalization. JAMA. 2005 Aug 10;294(6):699-705. PubMed PMID: 16091572.
- Mogensen SW, Andersen A, Rodrigues A, Benn CS, Aaby P. The Introduction of Diphtheria-Tetanus-Pertussis and Oral Polio Vaccine Among Young Infants in an Urban African Community: A Natural Experiment. EBioMedicine. 2017 Mar;17:192-198. doi: 10.1016/j.ebiom.2017.01.041. Epub 2017 Feb 1. PubMed PMID: 28188123; PubMed Central PMCID: PMC5360569.
- Zhang L, Prietsch SO, Axelsson I, Halperin SA. Acellular vaccines for preventing whooping cough in children. Cochrane Database Syst Rev. 2014 Sep 17;(9):CD001478. doi: 10.1002/14651858.CD001478.pub6. Review. PubMed PMID: 25228233.
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About two years ago, California’s governor, Jerry Brown, signed SB277 into law, which mandated that all school age children must have all vaccines appropriate for their age before they could enter private or public schools. The law nearly eliminated the ability to get personal belief exemptions (PBE), which allowed parents to object to vaccinations for almost any reason. The new law does allow for medical exemptions, that is, children who have some medical condition that contraindicates a vaccine may be exempted from these rules. As a result of this law, it was predicted that the California vaccine uptake for school age children would increase substantially, while reducing the incidence of vaccine preventable diseases.
Those of us who have been keen observers and supporters of SB277 were hoping for the best – that the vaccination rate in the state would show increases quickly. And it did.
Data released this week (pdf), from the California Department of Public Health, showed an exceptional increase in the percentage of California’s kindergarteners who were fully vaccinated (for their age group) – it rose from 92.8% to 95.6%. But, there’s even more astonishing data underneath that. With the advent of the new law, 97.3% of California’s kindergartners have received both MMR vaccinations, up from 94.5% in 2016 and 92.6% in 2014. The same was shown for diphtheria, tetanus and pertussis (whooping cough) vaccine – it went from 94.2% in 2015 to 96.9% in 2016. There should be cheering in the streets of California for the success of SB277.
The increase in vaccine uptake for all mandated vaccines is dramatic – not only does it show that SB277 has stemmed the overuse of personal belief exemptions that was slowly reducing California vaccine uptake, but it also has increased that uptake to levels far above historical. This graph illustrates how well the law has worked in a short period of time:
The best part of the law is that it’s increasing vaccine uptake in areas of the state where the overuse of PBEs was pushing the vaccination rate down. Most California’s counties have vaccination rates above 95%, which is considered the level at which the herd effect for measles vaccinations prevent the rapid spreading of the disease. Furthermore, only 4 relatively small counties in California have rates below 90%.
California state Senator Richard Pan (D-Sacramento), who is also a pediatrician and who was one of the primary supporters of SB277, tweeted out “Great News.” Obviously he’s ecstatic with this data on California vaccine uptake across the state.
Dr. Pan was interviewed by the Los Angeles Times, and said,
Measles certainly hasn’t gone away. We need to be sure to have our immunization levels high enough. The fact that this class and the state overall has now achieved this level is one further step to restore the community immunity we had before.
He also noted that the data shows the significant increase in very young children, kindergartners. He mentioned that there are still significant number of older children who are not vaccinated because of the lax requirements in previous vaccine laws, which made PBEs very easy to get. SB277 also requires 7th graders to be completely up-t0-date on their vaccines, so all children should eventually be caught up with their vaccines. Unfortunately, many students who have passed that 7th grade vaccination checkpoint may be insufficiently vaccinated. Or not vaccinated at all.
The University of California (UC) system has stated that it will require vaccines for all new enrollees at its 10 campuses (along with the UC Hastings College of Law which has decided to comply with the UC requirements). Like the state law, it eliminates all personal belief exemptions, but does allow medical ones. Eventually, this mandate will cover the over 230,000 students in the system.
The anti-vaccine forces have tried several tactics to block implementation of the new law. Opponents of SB277 filed a lawsuit last summer claiming the law violated California children’s right to an education under the state’s Constitution. A judge denied their demand for an injunction against the law – the plaintiffs eventually withdrew their case. These opponents also failed to gather enough signatures last year to put a referendum on the November ballot to overturn the law.
There are reasons to cheer all of this news out of California regarding immunization rates. But that’s just one state, albeit the largest and arguably the most influential state in the country. Other than California, only two other states have laws that have eliminated personal belief exemptions for immunizations – Mississippi and West Virginia, both of which have high vaccine uptake. And the easy availability of personal belief exemptions have lead many states to have vaccination rates of the MMR vaccine that are far below the 95% target. This graphic shows which states have significant deviations from the 95% standard for MMR vaccine (thanks to BuzzFeed News):
Sadly, it may not be possible for a lot of states to copy California’s success with vaccines. One of the worst performing states for the MMR vaccine is Colorado, and, according to BuzzFeed News,
Vaccine advocates in Colorado are envious of their counterparts in California. “We are watching California very closely, and kudos to them for getting that bill through,” Stephanie Wasserman, executive director of the Colorado Children’s Immunization Coalition, told BuzzFeed News.
She believes it would be very difficult to enact similar legislation in Colorado, which has libertarian conservatives who reject government mandates on vaccines, as well as liberal enclaves like Boulder where many parents seek out alternative health care and see vaccines as a tool of Big Pharma.
Libertarian conservatives and liberals on the same side of the fence on vaccines? The problem with both groups is that they ignore the health of children just to be “politically virtuous” about vaccines. Except they are scientifically and medically wrong.
So let’s give an ovation for hard working politicians of California, who decided that the health of the state’s children was the paramount consideration for vaccinations. Dr. Pan and many other state legislators decided that the most effective way of increasing the California vaccine uptake was to reduce the availability of personal belief exemptions. And they were right – California’s immunization rate has increased appreciably because of SB277.
Vaccines save lives.
The issues with the pertussis vaccine waning effectiveness has been circulating for several years. There have been a number of well-designed studies that have provided evidence of the issues with the pertussis component of the DTaP or Tdap vaccine (which also provides immunization against tetanus and diphtheria, both dangerous diseases).
According to current research, individuals who have been vaccinated against whooping cough (Bordetella pertussis), with either the DTaP (version for usually for children) or Tdap vaccine, lose protection against whooping cough in some time period after being vaccinated.
A new article, published in Pediatrics, written by Nicola P Klein et al., examined children who received the Tdap vaccine in the Kaiser Permanente Northern California (KPNC) health care plan, a vertically integrated managed care system which closely tracks patients after vaccination. Their data provide important information about the strategies for the vaccine going forward.
Continue reading “Pertussis vaccine waning effectiveness – the facts”
There is really only one reason to vaccinate – protecting everyone, especially children, from dangerous vaccine preventable diseases. We have eliminated smallpox. We have almost eliminated polio.
And we had almost made measles extinct, until the myth that the MMR vaccine (to prevent mumps, measles and rubella) caused autism, started by one of sciences greatest fraudsters, the defrocked Mr. Andy Wakefield. It’s a myth that’s been thoroughly and definitively debunked.
One vaccine preventable infectious disease that we’ve been unable to conquer is whooping cough (caused by the bacteria, Bordetella pertussis), also known as pertussis. Pertussis is a relatively dangerous infection, the disease itself has serious consequences for children and adults:
- 1 in 4 (23%) get pneumonia (lung infection)
- 1 or 2 in 100 (1.6%) will have convulsions (violent, uncontrolled shaking)
- Two thirds (67%) will have apnea (slowed or stopped breathing)
- 1 in 300 (0.4%) will have encephalopathy (disease of the brain)
- 1 or 2 in 100 (1.6%) will die
Whooping cough can be easily prevented by the DTaP or Tdap vaccines (which also protect against tetanus and diphtheria). The vaccines can be given to infants as early as 6 weeks to 2 months old.
As with all medical procedures, there are some adverse effects with the pertussis vaccines. Moderate adverse effects from the vaccine occur in about 1 in 10,000 (or even fewer) injections. The most severe effects, which may or may not be causally related to the vaccine since the rate is so low, are in the range of 1 out of a million doses.
One out of one million doses of the vaccine cause a serious adverse event (maybe). Compare that to the 1-2 out of 100 will die of the disease. Unless you flunk math, there is no rational reason to avoid the vaccine. Continue reading “Why we vaccinate – pertussis and epilepsy are linked”
Editor’s note: This article was originally published in January 2015. It has been revised to include information from a recent Australian Federal Court ruling that imposed fines upon the homeopaths.
On December 22, 2014 an Australian Federal Court ruled that Homeopathy Plus! Pty Ltd, LTD, and its creator and director, Ms. Frances Sheffield, engaged in misleading conduct in trade or commerce in making claims against the whooping cough vaccine and in support of homeopathic remedies as an alternative – or a second line of defense – for preventing whooping cough.
This was done after the Australian Competition and Consumer Commission (ACCC) asked the court to declare that it’s misleading and impose other penalties (detailed description of the court proceedings, and more information). In other words, they were asked to look into homeopathy honesty.
This article has two objectives:
- Provide a brief overview and summary of the decision.
- Determine whether similar action can be taken against those making similar claims in the United States.
Continue reading “Homeopathy, Honesty, and Consumer Protection”
There are many canards propagated by the vaccine deniers to support their personal beliefs (really, denialism) about the safety and effectiveness of vaccines. One of their more popular beliefs is that vaccines didn’t end many of the deadly diseases, but improved sanitation, healthcare, nutrition or magical fairies (also known as homeopathy) ended these diseases.
There is even a subgroup of these believers who think that the CDC, historians, and everyone else is lying about the epidemics that existed prior to vaccinations–let’s call this group history deniers. They reject the scientific and historical evidence that vaccines saved lives – amazing.
So, is there scientific evidence that vaccines actually ended these epidemics? Yes there is, and it’s unequivocal. Unless you want to embrace historical revisionism, and somehow all of the health care records and epidemiological information was faked, vaccines saved lives – lots of lives. Continue reading “Vaccines saved lives – scientific evidence”
There are so many silly memes that have arisen from the vaccine deniers, most of which have been thoroughly debunked. Everything from the well-worn (and worn-out) “vaccines cause autism” fable, which I have quashed here, to the “these diseases aren’t dangerous”, which, of course, couldn’t be farther from the truth.
One of the more annoying of the tales pushed by the vaccine refusers is that vaccines aren’t tested thoroughly before being used on unsuspecting infants. I do not know where this started, or why it started, but like much in the anti-vaccination world, it really doesn’t matter. It just passes from one person to another across google, and individuals with no research background hold this particular belief as if it were the Truth™.
Not only are vaccines thoroughly tested for safety and efficacy before being marketed, they also are rigorously tested in various combinations with other vaccines. And I’m not Cherry Picking a few articles to support my point of view, unless by cherry-picking you mean I’m picking the best articles from the highest quality journals in medicine.
Continue reading “Vaccines aren’t tested – myth vs. science (updated)”
Debunking anti-vaccine myths are one of the goals of this blog, which has evolved from my original intent of mocking anti-evolution lies. Mostly, the tactics of both science deniers are the same, so most of what I write is interchangeable–it was a natural evolution to vaccines.
Yes, I went there.
There are several tactics to criticizing the anti vaccination cult. For me, it’s being pejorative (hey, I call them a cult), being rude, and mocking them with all the fervor I can find in my brain. Since ALL of the evidence supports the fact that vaccines are relatively safe and very effective, short of someone actually bring the same volume of science that disputes that fact, making fun of the cult is my reason to exist.
I know my tactics aren’t very popular in the pro-vaccine world–I really have fun doing it.
Just so all of you understand this clearly, I do not discriminate in my mockery of pseudoscience. I’ve done much worse to the anti-evolution gang. And don’t get me started on the purveyors of junk medicine, like chiropractic, acupuncture and homeopathy–I seriously enjoy making fun of them all.
However, most pro vaccine writers are much more civil. Dorit Rubinstein Reiss, who writes here frequently, is quite courteous towards the anti-vaccination movement, despite the bigoted hatred that they send her way. Some of us think that she’s treated so badly probably because she’s so polite and civil.
To be fair, most pro-vaccine writers range from snarky and pointed to civil and supportive. Some writers try to hit a balance between the two extremes by being both tough and supportive (especially to that group that we all call “fence-sitters” who are the parents who aren’t sure about vaccines).
Dan Kahan, a Yale University law professor, has authored research that delves into cultural cognition which is the study of how individuals form beliefs about the amount of risk in certain situations based on their preconceived cultural notions of good behavior. He has called me out personally for using the “anti-science” trope with respect to evolution, climate change and vaccines.
Kahan presents some very convincing evidence that more civil discussions with vaccine deniers can be more helpful–obviously, I disagree, but Professor Kahan makes extremely valid points. I’m glad that there are dozens of other pro-vaccine websites who meet or exceed his recommendations on civility. I’m too exhausted from decades of fighting against pseudoscience and straight out science denialism to change my methods now. Like I said, I’m having too much fun doing it my way.
However, there seems to be a third way to deal with the anti-vaccination crowd. It probably will not convince the true believers who think that evidence is only what supports their point of view, like the crackpots at Age of Lying about Autism who still think that Mr. Andy Wakefield is some sort of hero.
No, it’s the fence sitters who should know the facts about vaccine preventable diseases – it should scare the crap out of them. Continue reading “Vaccine preventable diseases – much scarier than vaccines”
All 50 US states (along with several territories and DC) require mandatory vaccination for children entering public (and frequently, private) schools. This system has essentially ended most vaccine preventable diseases in the USA, including measles, polio, chickenpox, and many others.
Broad vaccination is considered one of the 10 greatest achievements in public health. Vaccines should probably be number 1 on the list. Overall, the immunization mandate has established a strong herd effect, which has generally ended transmission of these diseases.
Even though vaccinating children before they enter school is mandatory, there are ways around it, if you choose. Every state allows medical exemptions, which is based on a proven risk for a child to not be vaccinated with one or more vaccines. For example, some vaccines are produced in chicken eggs, and a tiny percentage of children are allergic. Medical exemptions are absolutely critical to the well being of the child, and no pro-science (pro-vaccine) writer or researcher would be opposed to those types of exemptions.
Furthermore, most states have vaccine exemption laws which allows personal belief exemptions (PBE). These PBEs fall into one of two groups–religious exemptions, that is, the parent “claims” that their religion is opposed to vaccines; or personal exemptions, which are simply based on the fact that the parents are opposed to vaccination for whatever reason that hits their brain after 20 minutes of Googling “facts.”
Most states allow both types of exemptions, some only allow religious exemptions, and one state, Mississippi, allows only medical exemptions. As a progressive, there is little positive I can say about Mississippi, but this is a major positive. So congrats Mississippi for caring about children, at least in this one important way. Continue reading “California’s vaccine exemption laws – clustering effects”