Friday, April 26, 2019

Maine's vaccine exemption bill supported by "false claims"

Four incorrect (but widely repeated) claims were made by Maine representatives to justify getting rid of religious and philosophical vaccine exemptions.  Here I list them and provide documentation to show why they are wrong.


1.  "Only 6 states have higher opt-out rates."  "We have one of the worst vaccination rates in the country."  The CDC published vaccination rates for all the states for the required number of doses for MMR, DTaP and chickenpox vaccine in kindergartners.

Table 1 shows the median vaccination rate for all states for the MMR is 94.0.  Maine's rate is 94.5.
The median rate for DTaP is 94.5.  Maine's rate is 96.6.
The median rate for chickenpox (Vaccinia) vaccine is 96.5.  Maine's rate is 96.7.

Maine’s rate for all children exempted from any required vaccine is 5.0%.  While this is exactly in the middle of all states, at first glance it appears very high.  On closer look (see the Figure at the end of the article) 23 or 24 states have lower vaccination rates, but lower exemption rates—because they have an appreciable number of students who are unvaccinated but have obtained no exemptions.  The CDC’s graph shows this for the MMR.  That is why Maine beats the median vaccination rates, but appears to have a high exemption rate.


FIGURE. Estimated percentage of kindergartners with documented up-to-date vaccination for measles, mumps, and rubella vaccine (MMR)*; exempt from one or more vaccines†,§; and not up to date with MMR and not exempt — selected states and District of Columbia,** 2017–18 school year
 The figure shows the estimated percentage of kindergartners with documented up-to-date vaccination for measles, mumps, and rubella vaccine (MMR); exempt from one or more vaccines; and not up to date with MMR and not exempt in selected states and District of Columbia during the 2017–18 school year.

2.  "We Need to Achieve Herd Immunity."  There is no established percentage of people who need to be vaccinated to achieve herd immunity,  Herd immunity numbers are estimates, which vary by disease and vaccine.  An NIH newsletter noted that mathematical models is where these percentages come from:  "Using mathematical formulas and computer programs, NIH-funded scientists like Lipsitch have developed models to determine what proportion of the population has to be vaccinated to eliminate the spread of disease." 

The textbook Vaccines 6th Edition, page 1399, shows that estimates from experts for needed vaccination rates have ranged from 50%-95%.  While Maine has small pockets with lower levels of vaccinations, there have been no significant  vaccine-preventable disease outbreaks in them.  (Given CDC-acknowledged pertussis immunity 3-4 years after vaccination of 9%, I do not consider herd immunity achievable for pertussis.) 

https://www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6702a1-H.pdf)

 3.  "Measles was eradicated, and now it is back."  Eradication of measles in the US was declared in 2000.  This designation by the WHO meant that measles  did not continuously circulate in the US.  It still doesn't —or didn't until some NY health depts failed to require isolation of cases and contacts in late 2018-2019.  But eradication did not mean that outbreaks stopped.  The US has had 10-20 measles outbreaks/year since 2000; 90% were due to travelers incubating measles when they entered the US, and 10% of cases were of unknown cause.  

https://www.cdc.gov/measles/cases-outbreaks.html

4. "Vaccines are Safe.  Vaccines are Effective.”  Well, vaccines are somewhat safe and somewhat effective.  Each vaccine is different.  Congress charged the Institute of Medicine (now called the National Academy of Medicine) with studying vaccine safety.  Its 2011 report on adverse events and vaccines concluded that the most important information (such as whether specific vaccines cause autism) has not been resolved.  The science is not settled.


"The Institute of Medicine (IOM) was charged by Congress when it enacted the National Childhood Vaccine Injury Act in 1986 with reviewing the literature regarding the adverse events associated with vaccines covered by the program, a charge which the IOM has addressed 11 times in the past 25 years. Following in this tradition, the task of this committee was to assess dispassionately the scientific evidence about whether eight different vaccines cause adverse events (AE), a total of 158 vaccine-AE pairs, the largest study undertaken to date, and the first comprehensive review since 1994.

The committee had a herculean task, requiring long and thoughtful discussions of our approach to analyzing the studies culled from more than 12,000 peer-reviewed articles in order to reach our conclusions, which are spelled out in the chapters that follow. In the process, we learned some lessons that may be of value for future efforts to evaluate vaccine safety. One is that some issues simply cannot be resolved with currently available epidemiologic data, excellent as some of the collections and studies are.

Here are all the conclusions of the Committee for adverse events possibly due to the MMR vaccine.  For most, the evidence is insufficient to judge:


Here are all the conclusions of the Committee for adverse events possibly due to the DTaP vaccine.  For most, the evidence is insufficient to judge:


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