Red-Shirting Kindergarteners

red shirt from

I have been having an ongoing online discussion with some friends about kindergarten readiness.  There has been a trend in our peer group, which is upper-middle class, to “red-shirt” children, mostly boys, who have fall birthdays, and even some summer birthdays, in kindergarten.  This means they will start kindergarten when they are on the verge of turning or just having turned six, instead of when they are just turning five.   Instead of being the youngest children in the class, they are the oldest children in the class.   There isn’t a lot research on the actual practice of red shirting but there is research that shows that the oldest children in a class statistically perform better.  I have a few observations on this.

Someone has to be the youngest in the class.

If all the children with fall birthdays wait a year to start kindergarten, as they will here in California when we finish shifting the cut-off date in a couple of years, then we just shift who the youngest kids in the class are.  I imagine this change in California is probably just going to lead to an increase in the “red-shirting” of children with summer birthdays.  As a parent you want the best for your individual child.  That is reasonable, but not every child can be the oldest in the class.  Someone has got to be the youngest.  If we continue on this trajectory we are just going to keep shifting the starting age of kindergartens upward.

Which kids are being re-shirted?

Children from homes with lower socio-economic status usually are not redshirted. Redshirting is an expensive option when both parents work or when the child comes from a single-parent household. An extra year outside of public education represents an extra year of daycare or preschool costs. Impoverished students will typically be younger than the other children in class. Since they are also entering school with fewer literacy skills than their peers (Foster & Miller, 2007), they are already behind their peers in terms of academics on the first day of kindergarten.

What if most of the children not being “red-shirted” are the ones that would benefit the most from it?  Take this totally made up scenario.  Bob and Jim are both turning six in October.  Bob comes from an upper middle class family, and has been attending a high quality preschool since he was three. Jim is from a lower class family, and has had no formal preschool.   Bob already comes in at an advantage of two points from having two years of preschool and much of what is taught in kindergarten he already knows, so he only benefits from being in kindergarten by one point.  Jim will learn so much in kindergarten that it will raise his achievement two points.  Delaying kindergarten for either kid will see an increase of one point in achievement.  If they both start kindergarten this year, at the end of the year Bob has an achievement of 3 and Jim has an achievement of 2.  Here’s a table:

Bob’s achievement Jim’s achievement Bob’s advantage
Both start kindergarten 3 2 1
Bob is red-shirted, but not Jim 4 2 2
Jim is red-shirted, but not Bob 3 3 0

In real life, most of the children be red-shirted are like Bob. This puts children like Jim at even more of a disadvantage, than they are already at with no preschool.

So what’s the bottom line?

A cut-off age is arbitrary.  As long as we have school structured the way it is there will be kids that are a full year older than other kids in the same grade.  Someone will always be at the disadvantage of being the youngest child in the class.  Because of this trend in red-shirting, those youngest children are more likely to also be at a disadvantage of being in a lower socioeconomic class.  None of this is very helpful if you are a parent trying to decide whether or not to delay kindergarten.  You can, however, reassure yourself of this: if you are in a position to be making this decision about your child, your child already has an advantage over a lot of other children, because they have a parent that cares and is in a position to make a choice.

Full disclosure

My son has an October birthday.  He started kindergarten when he was still four.  He is in first grade now.  He is among the youngest and smallest of his class.  His maturity level is somewhere in the middle.  Academically, he is near the top.


Organic Vs. GMO. Do I need to pick a side?

You should be on neither side. The side we should all be on is the side of producing the healthiest food in the most efficient way, with the least impact on the environment.  Sometimes this will mean using organic methods.  Sometimes it will mean using conventional farming methods.  Sometimes it will mean incorporating a novel technique like genetic engineering. The right way forward is to work together, not to have an ongoing fight where you have picked a side and sticking to it regardless of the facts.  Let’s look at this false dichotomy a little more closely.

organic_food from

What does the certified organic label tell you?

It tells you that the producers have checked off a list of guidelines.  It does not mean that there are no or even less pesticides used.  It just means that different natural pesticides have been used.  However, natural does not mean better or less toxic.  We should want to be able to choose foods that used the safest pesticides possible.  This might be a natural pesticide.  It might be a synthetic pesticide.  The organic label is telling you nothing about the safety of the pesticide just its origin.  Furthermore, despite what cherry picked studies that pro-organic people cite, the science overall shows no difference in the nutritional value of organic vs. conventional foods. There are ways to farm that maximize the nutritional value of crops, but such methods are not indicated by an organic label.

What does a GM label tell you? 

It tells you that an ingredient in the food was produced using genetic engineering.  It tells you nothing about the purpose of that engineering.  A GM product that is resistant to a herbicide,  like Monsanto’s Round-up resistant corn might be something you want to avoid.  Note that the problem with this GM product is not the genetic modification, but the fact that it is sprayed with more herbicide than a non-resistant variety. This is an example of a product that increases pesticide use.  On the other hand you might prefer to eat a GM Bt crop.  Bacillus thuringiensis toxin is one of the most common pesticides used by organic farmers in the form of a spray.  It is derived from soil bacteria. GM crops have been developed that produce the toxin themselves.  The upside is the GM crops effectively reduce pest by producing less toxin than would need to be sprayed on the crops for the same reduction in pests. This is an example of a product that decreases pesticide use.

Bottom line is when you pick up a package and it says “organic”, or “GM free”, or “contains GM products” , as packages at Whole Foods will soon be labeled, keep in mind that label is telling you absolutely nothing about how healthy that food is for you.  It is really just a marketing strategy, and a very effective one.  If you really want to get on the side of more healthy food, don’t fall into this trap.  Advocate for the healthiest most environmentally friendly food possible, no matter what technology is used to produce it.  Unfortunately there isn’t really a sticker that you can put on a box that can indicate that.

For more reading I recommend this blogger at Scientific America.  She digs far deeper into the issue than I do.

I don’t want my child to get shingles!


A couple days ago I saw a post on Facebook  expressing anger over how the chicken pox vaccine had caused a rise in shingles, and the request for anyone who’s child had chicken pox to let the poster know so she could bring her child over to get infected.  Does this make sense?  Let’s unpack it.

What is shingles?

Shingles or Herpes  Zoster is a painful rash caused by the same virus that causes chicken pox.  The varicella-zoster virus (VZV) is a herpes virus.  One of the characteristics of herpes viruses is that after the initial infection the virus lies latent in the body.  Sometimes it reactivates.  The reactivation of VZV can cause shingles.  In order to get shingles you have to be infected with VZV.

Is there an increase in shingles due to the chicken pox vaccine?

Maybe.  Studies on this are inconclusive.  The vaccine was introduced in 1995.  It may be too soon to tell.  However, an increase in shingles after the introduction of the varicella vaccine had been predicted.  This was hypothesized based on the idea that an effective vaccine program would eliminate much of the wild-type VZV circulating.  It is thought that the “boost” people who had previously had chicken pox received from contact with the circulating virus kept their immune systems primed for a reactivation event. If the latent virus were to reactivate in their body, their immune system would be able to fight it off before any symptoms of shingles manifested.  Based on this hypothesis a shingles vaccine was developed to be given to people over 60, who are at the most risk for shingles.

Can you get shingles from the chicken pox vaccine?

Yes, you can.  The varicella vaccine is a live attenuated virus, which means that it is a virus that has altered to make it less virulent.  It does remain in your body as the wild-type virus does, and it can reactivate and cause shingles.  Current research shows that it reactivates less often than the wild type virus does and causes a milder shingles outbreak, with less chance of complications.  Of course this research only covers the two decades since the vaccine was introduced.  It is currently impossible to know about effects in future.

In light of all of this, does purposefully infecting your child with chicken pox make sense?

Not if what you are trying to avoid in shingles.  Current research shows that you are more likely to develop shingles, and the case is likely to be more severe,  after naturally catching chicken pox than you are from the vaccine.  The only way to make sure you don’t get shingles is to make sure you never encounter the either the wild-type or the vaccine virus.

image from Microsoft Office Clip art

HIV cure?

If you AIDShave Facebook friends that are anything like mine, the other day your newsfeed was full of excitement about this baby in Mississippi being cured of HIV. If this is true, it’s pretty exciting, but we need to keep that excitement in perspective.  Let’s examine what this really means.

Is this really true?

Maybe.   The research has been presented at a scientific meeting.  It has not yet been published in a scientific journal.  This is what we know.  A baby was born to an HIV positive mother, who was not given the usual anti-retroviral treatment that is recommended for HIV-positive pregnant woman to prevent transmission of the virus to the baby.    Two days after birth the babies blood was tested twice and a viral load was found.  Thirty-one hours after birth the baby was put on an anti-HIV drug cocktail.  This is uncommonly early start for such a cocktail.  Blood tests were performed three more time in the following weeks, detecting a viral load.  At 29 days the viral load was undetectable, this is a normal outcome of anti-retroviral therapy.  At 18 months treatment was stopped by the caretaker.  The child was not seen for six months.  When the child was brought back to the doctor, they expected to find that the virus had begun replicating again.  They did not find that.  They did find genetic evidence of the virus, but not that it was replicating.

So what really happened?

They don’t really know.  This is an anomaly.  They did not see the child for six months.  It’s not entirely clear what exactly caused the virus to be knocked out.  Erv, a blogger who knows a whole lot more than I do about HIV has a thought about this:

Babby already had Moms adaptive immune response working for her. And at birth, she was immediately put on antiretrovirals.
Limited genetic diversity in the transmission event + pre-existing anti-HIV antibodies + immediate drug therapy =  They might have gotten the drugs there before the quasispecies was established, thus there were no drug resistant variants present. Antiretrovirals and antibodies from Mom could do their work. Babbys developing immune system had an easier target to catch.

The researcher presenting this case has a slightly different theory:

Persaud, who plans to present her findings in full at a conference session tomorrow, suspects that the early treatment prevented the establishment of a reservoir of long-lived CD4 cells that harbor latent HIV infections; these CD4 cells avoid immune detection and are impervious to antiretroviral drugs because they are not actively producing new viruses. These reservoirs are a central reason why the virus persists even after decades of antiretroviral treatment.

How big a deal is this if it is true?

It’s a fairly big deal, but not earth shattering.  It suggests that if we start treatment so quickly after infection we may be able to catch the virus before it mutates into a drug resistant quasispecies or becomes established in a reservoir in the immune system.  It’s hard to imagine how this could be ethically confirmed by studies.  This was a single case of a pregnant woman who was not known to be HIV positive until she was in labor.  The standard of care is to treat HIV-positive pregnant woman with anti-retrovirals to prevent transmission to the child.  When this standard of care is followed transmission is very rare.  Withholding the treatment from the mother would be unethical.  Researchers would only be able to study this on the few children who do get infected.  Most of the children infected today are infected because the mothers did not receive adequate pre-natal care.  They would be unlikely to be in a position to receive this aggressive treatment after birth as well.

So we haven’t cured HIV then?

No we haven’t.  This might be a pretty exciting development in the already very effective field of anti-retroviral treatment.   HIV is no longer a death sentence.  It is a chronic disease that needs to be closely managed.  What this does suggest is that it may be possible to stop the virus before a full infection is established if treated soon enough after transmission – a kind of “morning after pill” for infection.  That’s pretty exciting, but not helpful to all the people who already have HIV.

image from

If it’s on the internet it must be true, right?



Wrong!  There is all sorts of misinformation on the internet.  Anybody can write anything.  So when some makes a scientific claim or post a statistic how can you tell if it is true?  Well here are some steps you can take to find out if the claim is true.

  • Snopes is your friend.  The first thing I do when someone makes a claim is check for it here, “the definitive Internet reference source for urban legends, folklore, myths, rumors, and misinformation”.  Its primary focus is not on science, but it does contain some science topics.  It is great source for political nonsense.
  • Check some science blogs.  A good source for commentary on medical claims is Science-Based Medicine.  For general science I like to just search ScienceBlogs.
  • Look for the original source.  Often scientific journals are behind a paywall, but you should be able to at least read an abstract (a  short synopsis of a journal article that is usually placed at the front of the article.  All major medical journal article are catalog at PubMed.  Almost all blogs on the sites above will reference original articles.
  • Read everything with a critical eye.  Not all journal articles are equal.  Here are some things to look for.
    • How prestigious is the journal the article was in?
    • In cases of medicine, is it a study on humans or was it done on a lab animal?
    • How many subjects were there and what were the controls?
    • What do the investigators say about their research?  Often reporting about the research will make claims that go far beyond what the researchers claimed in the paper.

These are some good steps to take.  Almost every day I see something in my Facebook news feed that I am skeptical of.  In forthcoming post I will talk about some of the claims I am seeing and dig a little deeper than the nifty Facebook graphic.