Tag: attack rate

Dr. Bob Puts the Nail in the Coffin of the Herd Immunity Argument

Dr. Bob Sears, who actually wrote a book about vaccines, seems to think that he and his podcasting sidekick have put the nail in the coffin “of trying to use the herd immunity argument to justify coerced vaccinated.”

Dr. Bob seems to think that herd immunity doesn't apply to vaccines.

The meme he shared even includes the hashtag stating that herd immunity doesn’t apply to vaccines.

Dr. Bob Puts the Nail in the Coffin of the Herd Immunity Argument

While arguing against the idea of herd immunity and for coerced vaccination are common among anti-vaccine folks, neither is true.

Herd immunity is real and no-one is going to force anyone to vaccinate their kids. Vaccine mandates do not mean forced vaccination.

What about the idea that “all vaccines wane within about 2-15 years, leaving vaccinated children & adults unprotected?”

If that were true, then wouldn’t everyone who got sick in latest outbreaks be vaccinated? Why are most folks unvaccinated?

So we are either getting a lot of outbreaks because of waning immunity or your titers are getting boosted because you are getting exposed to so much natural disease. Got it?

While waning immunity is an issue for some vaccines, like mumps and pertussis, the primary and secondary failure rates are still not as bad as Dr. Bob suggests, which is why, in an outbreak, the attack rate of disease is always higher among those who are unvaccinated and unprotected.

The numbers don't always add up correctly when anti-vax folks try to do math.
The numbers don’t always add up correctly when anti-vax folks try to do math.

Is herd immunity the main argument that’s made when experts suggest we need stronger vaccine laws? I always thought the main argument is that folks should just vaccinate and protect their kids, but maintaining herd immunity so that your intentionally unvaccinated kids don’t put everyone else at risk is a good reason too.

Does everyone see the problem with Melissa Floyd’s math? This probably won’t be on the SAT, but you still want to get this right…

Like many others are doing right now, she used state level data. Since many of the folks who don’t vaccinate their kids cluster together in the same communities and schools, the “2% of those filing for exemptions” end up making up 10, 20, or even 30% of some school’s student population.

“This means if you are a primary non-responder, you are walking around every day with a false sense of security, clinically unvaccinated for that particular disease.”

Melissa Floyd

This is the whole point of herd immunity!

Because vaccines aren’t 100% effective, we can walk around all day without actually thinking about it much, hoping that we can rely on the fact that most other people are also vaccinated and protected. That keeps disease out of our community or herd.

The system typically breaks down though, not because vaccines aren’t effective enough, but because too many folks don’t get vaccinated.

“A 2011 article in “Vaccines”, edited by Stanley Plotkin, says, “Much of the early theoretical work on herd immunity assumed that vaccines induced solid immunity against infection…” Theoretical… Assumed…”

Melissa Floyd

She should have read the whole article, or at least used the whole quote…

“Much of the early theoretical work on herd immunity assumed that vaccines induce solid immunity against infection and that populations mix at random, consistent with the simple herd immunity threshold for random vaccination of Vc = (1-1/R0), using the symbol Vc for the critical minimum proportion to be vaccinated (assuming 100% vaccine effectiveness). More recent research has addressed the complexities of imperfect immunity, heterogeneous populations, nonrandom vaccination, and freeloaders.”

Herd Immunity: A Rough Guide

It doesn’t say what she thinks it says…

“Indeed, one might argue that herd immunity, in the final analysis, is about protecting society itself.”

Herd Immunity: A Rough Guide

So why haven’t we eradicated measles like we said we would?

“What’s funny is after the measles vaccine was licensed in 1963, the medical community declared a goal of eradicating measles by 1967. But 1967 came and went and it still wasn’t gone, 1977, 1987, 2000… the dates kept getting pushed, and the result was always the same. Meanwhile they continued to increase the hypothesized “herd immunity threshold”, eventually winding up at the extremely high 95% you hear today. “

Melissa Floyd

That’s actually a good question.

What happened to the previous goals of eliminating measles?

“In 1966, the USA began an effort to eradicate the disease within its own borders. After a series of successes and setbacks, in 2000, 34 years after the initial goal was announced, measles was declared no longer to be endemic in the USA.”

Orenstein et al on Eradicating measles: a feasible goal?

Along the way, we have gone from an estimated 100 million cases and 5.8 million deaths in 1980 and an estimated 44 million cases and 1.1 deaths in 1995 to “just” 7 million cases and 89,780 deaths in 2016.

“Under the Global Vaccine Action Plan, measles and rubella are targeted for elimination in five WHO Regions by 2020.”

Measles

While there is doubt that we can truly eradicate measles with the current vaccine, we can certainly control and eliminate measles if folks stop listening to anti-vaccine propaganda and they get vaccinated and protected.

More on Dr. Bob and His Herd Immunity Arguments

Propaganda Busting Confirms Anti-vaccine Sites Photoshop Images

Spend a few minutes going through our list of anti-vaccine PRATTs, and you will quickly realize that they just push misinformation and propaganda.

Propaganda Busting Confirms Anti-vaccine Sites Photoshop Images

How easy is it to refute their claims?

Consider this “article” about measles outbreaks

It shows an infant with chicken pox.

While that could be a simple mistake, it is actually a Photoshopped stock image of an infant with chicken pox that adds a big scary needle and syringe, that I guess is supposed to represent a vaccine.

Where's the syringe and needle?
Where’s the syringe and needle?

The thing is, neither the chicken pox nor MMR vaccine look like that and neither would be given with such a long needle!

In fact, that needle is about twice the size as any needle that would be used on an infant or toddler, which is why they had to Photoshop a separate photo of a big syringe and needle onto the infant with chicken pox.

It's just a stock image of a big syringe and needle...
It’s just a stock image of a big syringe and needle…

Now that you know that the photo is make-believe, you shouldn’t be surprised that their “article” is too.

This erroneous thinking has led the public, media and government alike to attribute the origin of measles outbreaks, such as the one reported at Disney in 2015 (and which lead to the passing of SB277 that year, stripping vaccine exemptions for all but medical reasons in California), to the non-vaccinated, even though 18% of the measles cases occurred in those who had been vaccinated against it — hardly the vaccine’s two-dose claimed “97% effectiveness.”

Government Research Confirms Measles Outbreaks Are Transmitted By The Vaccinated

By itself, the number of cases in an outbreak doesn’t exactly tell you a vaccine’s effectiveness. You also have to know something about how many people were vaccinated and unvaccinated and the attack rate, etc.

“Among the 110 California patients, 49 (45%) were unvaccinated; five (5%) had 1 dose of measles-containing vaccine, seven (6%) had 2 doses, one (1%) had 3 doses, 47 (43%) had unknown or undocumented vaccination status, and one (1%) had immunoglobulin G seropositivity documented, which indicates prior vaccination or measles infection at an undetermined time.”

Measles Outbreak — California, December 2014–February 2015

Anyway, in the Disneyland outbreak, if you do the math correctly, you can see that only 8 of 110 were fully vaccinated, or about 7%.

What does that tell you about vaccine effectiveness?

Not much!

Again, we don’t know how many vaccinated vs unvaccinated folks were exposed and didn’t get measles.

We can guess though…

Most folks are vaccinated, even in California. So the fact that only 7% of the people that got measles in the outbreak were fully vaccinated actually says quite a lot about how effective the MMR vaccine really is.

What about the idea that vaccinated people are starting outbreaks and spreading measles?

While the vast majority of measles outbreaks are in fact traced to someone who is unvaccinated, there was one outbreak in 2011 that was “started” by someone who was vaccinated.

“She had documentation of receipt of MMR vaccination at 3 years and 4 years of age. There was no travel during the incubation period and no known sick contacts. However, the index patient worked at a theater frequented by tourists.”

Outbreak of Measles Among Persons With Prior Evidence of Immunity, New York City, 2011

Since even the MMR vaccine isn’t 100% effective, is it really so surprising that occasionally, someone who received two doses of the vaccine could get measles and pass it to others, especially considering that around 220 people got measles in the United States that year?

“During 2011, a provisional total of 222 measles cases were reported from 31 states… Most patients were unvaccinated (65%) or had unknown vaccination status (21%). Of the 222, a total of 196 were U.S. residents. Of those U.S. residents who had measles, 166 were unvaccinated or had unknown vaccination status, 141 (85%) were eligible for MMR vaccination, 18 (11%) were too young for vaccination, six (4%) were born before 1957 and presumed immune, and one (1%) had previous laboratory evidence of presumptive immunity to measles.”

Measles — United States, 2011

Is the MMR vaccine a failure because there were some still some outbreaks in the 1980s, before we started to give kids a second dose? The attack rate in many of these school outbreaks, in which many kids had one dose of MMR, was still only about 2 to 3%.

It is safe to blame a failure to vaccinate and intentionally unvaccinated kids for most of the recent measles outbreaks.

Is the MMR vaccine a failure because we still have outbreaks among intentionally unvaccinated kids and every once in a while, in someone who is fully vaccinated who gets caught up in an outbreak?

Of course not!

It is easy to do a little research, consider what disease rates looked like in the pre-vaccine era, and know that vaccines work and that they are necessary.

More on Propaganda Busting Confirms Anti-vaccine Sites Photoshop Images

Is This Year’s Flu Vaccine Working?

Breaking News – Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness have now been released (see below)

Flu season is just getting started, but I’m sure that you have already heard folks rating how well this year’s flu shots are working.

Are flu vaccines working well?
Are flu vaccines working well?

Of course, if you had a flu shot and have already gotten the flu, then you’re gonna think the flu shot isn’t working very well at all.

And if you are vaccinated and protected and have avoided the flu, then it is working so far, right?

Is This Year’s Flu Vaccine Working?

While we won’t know how well this year’s flu vaccine is working until the CDC releases the preliminary estimates on flu vaccine effectiveness, there are some good signs already.

  1. The majority of the influenza viruses collected from the United States so far have been “characterized antigenically and genetically as being similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.”
  2. The most frequently identified influenza virus type reported by public health laboratories was influenza A(H1N1)pdm09 virus.

Remember, to be effective, you want the flu vaccine to match the strains of flu virus that are circulating in the community. A mismatch in flu virus strain or antigenic drifting leads to lower flu vaccine effectiveness (VE).

Remember the 2004-05 flu season? That was the year that because of a drifted A(H3N2) virus, “only 5% of viruses from study participants were well matched to vaccine strains.” And the flu vaccine wasn’t very effective at all.

Still, even when the flu vaccine matches circulating strains, in general, as we have certainly seen, “flu vaccines provide better protection against influenza B or influenza A (H1N1) viruses than against influenza A (H3N2) viruses.”

YearFlu Virus StrainVE
2004-05A(H3N2)10
2005-06A(H3N2)21
2006-07A(H1N1)52
2007-08A(H3N2)37
2008-09A(H1N1)41
2009-10A(H1N1)pdm0956
2010-11A(H3N2)60
2011-12A(H3N2)47
2012-13A(H3N2)49
2013-14A(H1N1)pdm0952
2014-15A(H3N2)19
2015-16A(H1N1)pdm0948
2016-17A(H3N2)40
2017-18A(H3N2)40
2018-19A(H1N1)pdm0947

So if you had to guess, you could probably say that this year’s flu vaccine is going to be at least 50% effective.

So just as good as flipping a coin? Not exactly.

There are a lot of benefits to getting a flu shot besides avoiding the flu, like avoiding severe flu, hospitalization, and death.

And since flu vaccines are safe and flu can be a life-threatening disease, even in those without any medical problems, wouldn’t you take any chance you could to reduce your child’s chances of getting sick?

When will we know how well this year’s flu vaccine is really working?

The CDC typically releases the first preliminary flu vaccine effectiveness report of the season in February.

Not that you should wait! Flu season is well underway and this is a great time to get a flu vaccine and get protected for the rest of flu season.

Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness

On schedule, the CDC has released this year’s Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness.

During this period, overall adjusted vaccine effectiveness against all influenza virus infection associated with medically attended ARI was 47% (95% confidence interval [CI] = 34%–57%). For children aged 6 months–17 years, overall vaccine effectiveness was 61% (44%–73%).

Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness — United States, February 2019

That’s certainly better than we have seen in recent years.

More on the Effectiveness of This Year’s Flu Vaccine

Updated February 15, 2019

Do More Vaccinated or Unvaccinated Kids Get Pertussis?

While this seems like a simple question, the answer is a bit more complicated than most people imagine.

Do More Vaccinated or Unvaccinated Kids Get Pertussis?

For anti-vaccine folks, the answer is clear – more vaccinated kids get pertussis. They put all of the blame for pertussis outbreaks on waning immunity. Of course, that’s not the whole story.

While 10% of kids got pertussis, unless you are at a Waldorf school, it is unusual to find that many completely unvaccinated children.
While 10% of kids got pertussis, unless you are at a Waldorf school, it is unusual to find that many completely unvaccinated children. Plus, we don’t know the vaccine history of 40% of these kids.

While it might technically be true that more vaccinated kids get pertussis in the average outbreak, that’s only because there are many more vaccinated kids!

A more accurate and useful answer, taking into account attack rates, makes it clear that a higher percentage of unvaccinated kids get pertussis in these outbreaks.

“In conclusion we have described a school-based outbreak of pertussis that may have been fueled by moderate vaccine effectiveness combined with a failure to vaccinate.”

Terrenella et al on Vaccine effectiveness of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine during a pertussis outbreak in Maine

In a pertussis outbreak in Maine, attack rates were much higher in unvaccinated kids, even though more vaccinated kids got pertussis. While 29 of 214 vaccinated kids got pertussis, a much higher percentage of unvaccinated kids got sick – 6 of 28.

That means your risk of getting pertussis was much higher if you were unvaccinated.

A 2013 pertussis outbreak in Florida is a good example that even with all the bad press it gets, the DTaP and Tdap vaccines work too. This outbreak was started by an unvaccinated child at a charter school with high rates of unvaccinated kids. About 30% of unvaccinated kids got sick, while there was only one case “in a person who reported having received any vaccination against pertussis.”

In another 2013 pertussis outbreak in Florida, this time in a preschool, although most of the kids were vaccinated, the outbreak started with “a 1-year-old vaccine-exempt preschool student.” And the classroom with the highest attack rate, was “one in which a teacher with a laboratory-confirmed case of pertussis who had not received a Tdap booster vaccination, worked throughout her illness.”

Why do so many unvaccinated kids get pertussis these days?

“We found evidence of an increase in exemption rates, spatial clustering of nonmedical exemptions, and space-time clustering of pertussis in Michigan. There was considerable overlap between the clusters of exemptions and the clusters of pertussis cases.”

Omer et al on Geographic Clustering of Nonmedical Exemptions to School Immunization Requirements and Associations With Geographic Clustering of Pertussis

Besides the fact that they are unvaccinated and unprotected?

“Children of parents who refuse pertussis immunizations are at high risk for pertussis infection relative to vaccinated children. Herd immunity does not seem to completely protect unvaccinated children from pertussis.”

Glanz et al on Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children.

They can’t get away with hiding in the herd.

Another important consideration – in addition to the fact that more unvaccinated kids get pertussis, when they get pertussis, it is more severe than those who are vaccinated.

“Serious pertussis symptoms and complications are less common among age-appropriate number of pertussis vaccines (AAV) pertussis patients, demonstrating that the positive impact of pertussis vaccination extends beyond decreasing risk of disease.”

McNamara et al on Reduced Severity of Pertussis in Persons With Age-Appropriate Pertussis Vaccination-United States, 2010-2012.

Still thinking of skipping or delaying your child’s pertussis vaccine?

More on Do More Vaccinated or Unvaccinated Kids Get Pertussis?