vaxed vs unvaxed study!

[carriebft]

I know this is the type of study many here have been waiting for and asking for, though not perfect since its looking back but better than a lot of what we have:

http://www.sciencedaily.com/releases/2011/03/110304091458.htm

In their study, the authors compare the occurrence of infections and allergies in vaccinated and unvaccinated children and adolescents. These include bronchitis, eczema, colds, and gastrointestinal infections.

The evaluation showed that unvaccinated children and adolescents differ from their vaccinated peers merely in terms of the frequency of vaccine preventable diseases. These include pertussis, mumps, or measles. As expected, the risk of contracting these diseases is substantially lower in vaccinated children and adolescents.

the paper is here with the methods outlines:

http://www.aerzteblatt.de/int/article.asp?id=80869

[ema-adama]

How reliable can the results be when you are comparing 13,359 to 94?

[carriebft]

you feel you can get nothing because the numbers are unequal? there are some reliable stats that can come of such numbers. It's not like, say, 12 v 4 or something ridiculous like that as we have seen released and touted as a study before, kwim?

[carriebft]

not saying its perfect, but there are some interesting bits in there. and obviously room for more study; the next measure I would think that would be useful would be unvaxed, lesser vaxed, full vaxed, and i assume they could provide this with the data they already have

sorry for errors nak

[ema-adama]

No, I do think that it would be relevant to look more closely at what was found in the study. After all it is comparing two different groups of children, one vaccinated and one not. I am not saying this is a useless study - only that it is not a conclusive study.

When two children out of 94 unvaccinated have asthma (and only in the 11-17 year old group - none under 10 years old), it becomes difficult to attach any significance to the numbers. Obviously a problem with the sample size.

I do think it would be relevant to do this study with a larger group of unvaccinated children (in the US alone it is somewhere around 100,000 - I think). It would then also be interesting to compare this study with a study done with a larger sample.

I am curious what you think the strengths and weaknesses of the study are.

[xmasbaby7]

I read all of the data summary, and in every instance, the rate of infection was superior for unvaccinated children, yet the narrative concludes "no significant difference".

Am I reading this wrong or is this just an effort to spin with subtlety?

[just_lily]

Do you mean the rate of infection is higher for vaccinated children?

I think the issue is that because the sample size of unvaccinated children is so small the margin of error is huge.  So for example, it says:

The lifetime prevalence of at least one atopic disease among 1- to 5-year-olds was 12.6% (5.0%–28.3%) in unvaccinated children and 15.0% (13.6%–16.4%) in vaccinated children.

The numbers in brackets is the margin of error.  So in the unvaccinated kids the rate of disease was 12.6% of the sample size, but because the sample was so small it could be anywhere from 5% to 28% in the total population. 

The vaccinated sample was much larger, so the error is smaller.   Only 14% to 16%. 

So when you count in the margins of error, there really isn't any significant difference between the groups in this study. That is why a larger sample would be important.

My other concern is that they lumped all kids who got any vaccines together, even if they only ever got one.  I think that could definitely skew the results as well.  I would have preferred to have a sample of fully vaccinated kids as per goverment schedule, and a sample of completely unvaccinated kids.  Including partially vaxed kids or kids vaxed on an alternative schedule just adds way too many variables. 

All that being said, I am glad they are doing this at all.  Definitely a step in the right direction.