Talking to Your Girls: The Best Vaccine of All

In a previous posting, I noted that there are almost no studies looking at whether giving the human papillomavirus (HPV) vaccine to adolescents increases unsafe sexual behavior -- what some call a passport to promiscuity for girls and a license to drill for boys.  Although there are still no studies looking at behavior post-vaccine, the Archives of Pediatric and Adolescent Medicine just published a study on the attitudes and beliefs of girls who got the HPV shot.
The authors asked the girls (ages 13-21) to agree or disagree with statements like, "After getting the shot against HPV, I am less worried about getting a sexually transmitted disease other than HPV," and "After getting the shot against HPV, I think that condom use (or having fewer sexual partners) is less necessary."

First, the good news:  Only 4% of the girls felt less of a need to practice safe sex because of the vaccine.  The investigators then looked at what factors were associated with this belief.  Some risk factors were predictable, but a few were surprising.  A lower perceived need for safe sex was associated with:

• Lower knowledge about HPV and the vaccine
• Lack of condom use at last intercourse
• Lack of maternal communication about the HPV vaccine
• Teacher or physician serving as the source of HPV vaccination information

The last one threw me for a loop.  Surely the most reliable information about the vaccine and STDs comes from doctors and sex education teachers?  The problem is that even if they are dispensing appropriate advice (which may or may not be a correct assumption) , they may not be doing so in a way that's understandable to teens and their mothers.  On the flip side, it looks like moms can have a positive impact in their daughters' behavior, particularly if they talk to them about the limitations of the vaccine, including its lack of protection against some HPV strains, other STDs and pregnancy.

Though very few girls agreed that the vaccine would allow them to have more unprotected sex, survey answers don't necessarily predict behavior.  Even before the vaccine, over half of the adolescents in this clinic were sexually experienced, and most were not using condoms reliably.  It's doubtful that the vaccine will decrease the rate of unsafe sexual practices, unless it's accompanied with appropriate counseling.

So does this mean we shouldn't be vaccinating our daughters against, because of the theoretical increased risk of unsafe behavior?  Of course not.  The advent of effective antiretroviral therapy for HIV in the late 1990's was accompanied by an increase in the rate of unprotected sex, and subsequent gonorrhea and syphilis epidemics, in gay and bisexual men.*  Yet it would be completely unethical to withhold effective drug therapy because of its unintended behavioral consequences.  No, it simply means that doctors and, more importantly, parents have our work cut out for us when it comes to educating our kids.

*Despite the increases in other STDs in the San Francisco Bay Area, there was no increase in the HIV incidence in gay men during this time period.  The theory is that HIV-positive men had unsafe sex only with HIV-positive men, and HIV-negative only with HIV-negative.

Vaccinonomics

Warning:  This is one of my wonkier postings.  Read on if you'd like to learn more about the supposed science of economic analysis, and how it shapes healthcare policy.

How much would you pay to keep this little critter away from your child?*

I don't have a compelling personal anecdote about meningitis, and I hope I never do.  Meningococcus is one of the more common causes of meningitis, and this bug gives even hardened doctors and nurses the heebie-jeebies.  For one thing, it spreads by close contact, so members of the same household, or healthcare workers exposed to secretions, must take antibiotics to ward off the same fate.  And if you don't die from meningococcus, you could end up with brain damage or multiple limb amputations, since one of the complications is gangrene.

So we should be thrilled that there's a vaccine against the most common serotypes that cause disease in adolescents and young adults, who are particularly susceptible to this infection.  In the past, a single dose at age 11 or 12 was thought to be protective for 10 years, but recent studies have found that immunity lasts for only five.  Last week, the American Academy of Pediatrics issued a statement recommending a second, booster dose for 16-year-olds.

No one argues that adding a booster won't save lives.  But is it worth the extra cost, given that meningococcus is still a relatively uncommon disease?  Already, kids routinely receive about 30 shots in their childhood -- double the number back in 1980.  An editorial in the New England Journal of Medicine argued that "routine adolescent [meningococcal vaccine] does not provide good value for money, largely because of low disease incidence rates and relatively high vaccine cost."

You might argue that you can't put a price on a human life, but it turns out you can.  Economic analysis is the science of quantifying the cost of healthcare interventions, but as you'll see, there are a lot of smoke and mirrors involved.

Let's start off with the basics.  One way to measure the cost-effectiveness of a vaccine (or a pill, or seatbelts, or virtually anything) is to express it in dollars per life-year saved.  You can see right away that if you had a vaccine that was equally effective across all age groups, it is cheaper to save the life of a baby than the life of a 70-year-old, since you could potentially add 80 years to the baby's life, but only 10 years to Grandpa's.  It doesn't mean the baby's life is worth more, only that the vaccine is a bargain when given in infancy.

Some illnesses rarely cause death, but there may still be value in preventing them, to avoid complications, hospitalizations or lost productivity.  So most economists use the measure of dollars per quality-adjusted life-year, or QALY, saved.  How do economists quantify quality?  Simple: They ask patients, "If 1 is the value of a perfectly healthy life, and 0 is death, how would you rate having this condition?"  Suffering through a cold might be 0.999, while being hooked up to a ventilator and feeding tube might be 0.1.  (There are no negative numbers in quality-of-life estimates, though there are probably some fates worse than death.)  Already, you can see one of the inherent problems with economic analysis -- quality is an extremely subjective measure.

The other methodologic difficulties with this type of research involve knowing what to include in the accounting of costs and benefits, and which estimates to use.  Do you analyze the economics from the individual's standpoint, or society's, or the third-party payer's?  Each analysis is specific to its country; you can't take an analysis from, say, Singapore, and apply it in the U.K.  Although our body of scientific knowledge is constantly changing, economic analyses become rapidly outdated as costs fluctuate.  Econ analysis for vaccines is especially tricky, since you have to take herd immunity into account.  In other words, the benefits of immunization may extend beyond the immunized.


One popular myth is that a "cost-effective" intervention saves money.  In fact, most modern prevention and treatment measures don't save money at all.  The biggest exception?  Almost all routine early childhood immunizations, such as the measles and polio vaccines, save money.  The same isn't true, though, for the newer vaccines targeting tweens and teens.  Why is that?


Well, for one thing, adolescents are a hardy group.  Their immune system is stronger than infants', and when they do die, it's often a result of their own stupidity -- think of texting while driving.  On top of that, there's no loss in productivity when they're sick.  (Insert your own lazy teenager joke here.) An adult takes time off from work for illness, and a parent needs to stay home with a sick toddler, but a jobless16-year-old with the flu can fend for himself.  And then there's the fact that the newer vaccines aimed towards this age group are a lot more expensive than the older ones.  So let's look at the cost-effectiveness of some of these vaccines in the U.S.:


Meningococcus is one of the more expensive, with $88,000 per QALY saved.  Giving the double dose ends up being about the same price, since even though you double the cost, you save more lives.

Annual influenza vaccine in 12- to 17-year olds is very pricey, at $119,000 per QALY.  Compare this to only $11,000 per QALY in 6 to 23-month olds.


Human papillomavirus virus (HPV) wasn't too bad, at $15,000 to $24,000 per QALY, although it's much more expensive to vaccinate boys than girls, since cervical cancer is more common than penile or anal cancer, and reducing HPV in girls should reduce the frequency of screening and treatment of pre-cancerous lesions.

Hepatitis A ranged from cost-saving in college freshmen to $40,000 per QALY in 15-year-olds.  (The wide range should clue you in to the fragility of these economic models.)


The cheapest vaccine?  Pertussis booster, at the bargain basement price of $6,300 per life-year saved.  Outbreaks of pertussis, or whooping cough, have been linked to waning immunity in adolescents and adults, and while whooping cough is not particularly dangerous to older kids, it's very contagious and can kill unimmunized newborns.  Much of its cost-effectiveness derives from herd immunity and the fact that pertussis is an older, cheaper vaccine.  Middle school students in California are now required to get the pertussis booster.


Of course, these numbers give the illusion of hardness to a science that's based on the softest of data.  And what is the definition of a "cost-effective" intervention anyway?  By convention, a maximum limit of $50,000 per QALY saved is considered cost-effective.  There's no logical reason why this number appears in the literature.  It hasn't budged in the past two decades, despite inflation.  And $50,000 may be a year's salary for one family, or the price of a car for another.  But that's the figure in the minds of policy makers when they try to decide whether a new treatment should be covered by insurance.

Here's another way of looking at the numbers:  The NEJM editorial laments that the public-sector cost of immunizing one child until adulthood (not including annual flu vaccines) is about $1,450 for males and $1,800 for females.  I was surprised to see that this number was so low.  After all, we spend much more than that educating and clothing our children.  Heck, $100 a year is less than my caffeine budget.  Shouldn't we be spending at least that much to keep our kids healthy?


*For you microbiologists out there, this is technically gonorrhea -- but it's in the same family of bacteria.  Giant Microbes apparently found there's a bigger market for an STD than for meningitis.

One More Round on HPV

On previous blog posts, I advocated for mandatory HPV immunization in girls, but not necessarily in boys.  Well, I've changed my mind.  The vaccine should also be mandatory in boys.


A recent study confirmed what most epidemiologists have suspected for a while -- HPV is fueling the stratospheric, 225% rise in oropharyngeal cancers, involving such structures as the tongue and tonsils.  In the past, most of these cancers have been associated with tobacco and alcohol.  Rates of oral sex have been increasing, as many regard it as being safer than intercourse*, so the combination of that behavior and decreasing smoking rates means that 70% of oropharyngeal cancers are now due to HPV infection.  ("Human papillomavirus and rising oropharyngeal cancer incidence in the United States.")  HPV-positive oropharyngeal cancers can be seen in patients as young as 35 or 40.  While they tend to have a better prognosis than those who have tobacco-related cancer, standard treatment includes a toxic brew of radiation, chemotherapy and/or major surgery, including glossectomy (tongue removal).  There is no such thing as an oral Pap smear, so oropharyngeal cancer is often diagnosed late.  Probably one of the most famous patients is celebrated chef Grant Achatz of the restaurant Alinea, who was diagnosed with advanced tongue cancer in 2007.

This tongue dish from Alinea came from a duck, not the chef.

Fortunately for him and his fans, Achatz managed to avoid a glossectomy, and with aggressive therapy, he is now in remission.  Unfortunately, if current trends continue, projections show that the number of HPV-related oropharyngeal cancers will exceed the number of cervical cancers by 2020, and over half will be in men.


Of course, current trends don't have to continue, not if we make HPV vaccination mandatory in all preteens.  Although oropharyngeal cancer has not been a studied endpoint in any of the vaccine trials, one can make an educated guess about the expected efficacy.  HPV causes 70% of oropharyngeal cancers, 90 to 95% of which are due to HPV-16.  The HPV vaccines protect against HPV-16 with 90 to 98% efficacy in an unexposed population.  Using the most conservative numbers, the HPV vaccines should prevent 57% of orophayngeal cancers if given early. 

So do your family a favor.  Vaccinate your kid, and save a tongue.

*It's not an urban legend.  Oral sex is safer than other kinds of sex in terms of HIV infection.  One episode of receptive oral sex with an HIV+ partner carries a 0.06% risk of infection, compared to 0.1-0.2% for receptive vaginal and 0.3-3% for receptive anal.  And oral sex is widely believed to have a lower rate of pregnancy.

Banishing the Boo-Boos

When J.J. was four, he had a psychotic break at the doctor's office when they tried to give him his shots.  It took four adults to hold him down, and for years afterward, at every visit the nurse would chirp, "Oh, here's the strong one again!" Now that flu season is approaching, trypanophobia* is setting in again.

Then I saw a blurb in a parenting magazine about Buzzy, a vibrating ice pack used to reduce the pain of needlesticks:

"Getting shots is fun with Buzzy!"

There have been two small, randomized studies on Buzzy showing positive results, the first performed on adults using a crude but charming prototype:

Buzzy reduced the pain of IV insertion by a modest 1 point on a 10-point scale.  I wanted to try it on my own kids until I saw the $35 price tag.  For that amount, I could buy them a bottle of whisky and bullet to bite on.

The science behind Buzzy is that applying alternative sensations to the poked arm will keep the nerve fibers occupied, reducing conduction of pain impulses.  It's an often used strategy in pain control, though the efficacy varies widely according to the population being studied.  Another study applied this "vibrating instrument" to the opposite extremity to distract from the pain of immunization:

Combined with other measures, this contraption reduced pain in young children.  So go ahead, moms, feel free to bring your "personal handheld massagers" to the doctor's office!

You might wonder how researchers measure pain.  Pain is difficult to study, and even more so in children.  Pain scales using happy and sad faces can be used in older kids and their parents, but you have to get creative in infants and toddlers.  Scientists can measure duration of crying, heart rate and oxygen levels.  (You know that prolonged silence before a baby launches into The Serious Wail?  Well, he's holding his breath, and his oxygen levels are dropping.)  My personal favorite is the Neonatal Facial Coding System, which looks at 9 facial features to assess if an infant is in pain:

Though it's probably sensitive, I have reasons to doubt its specificity.  Here's JoJo after getting doused with a hose:

His score is a full 9, but he's not in pain -- only cold, wet and humiliated.

There are hundreds of randomized, controlled trials looking at ways to reduce needlestick pain.  The best validated is sugar water in infants, with at least 44 studies enrolling nearly 4000 babies.  No one knows for sure why this works.  It's not due to sucking, as sugar water is superior to breastmilk, formula or water, and it doesn't even have to be given during the shot.  Two milliliters given right before the needle is effective.  One theory is that the sweet taste results in a release of endogenous opioids, the same mechanism by which chocolate is thought to work.  But when one group of doctors gave Narcan, the heroin antidote, to babies receiving sugar water, they still cried less than babies who didn't get the sugar.  Anecdotally, sweet solutions are amazing. I gave J.J. a juice bottle throughout his circumcision, and he didn't make a peep. (That's right, I assisted in his back-alley circumcision -- but that's a subject for another blog post.)

The data on sweet solutions are more mixed in children over the age of 1.  Browsing through the abstracts on Pubmed, here are some of the strategies that have generally been shown to reduce needle pain, based on randomized, controlled trials:**

• Topical anesthetic creams
• Television (specifically, the mind-numbing Teletubbies)
• Distractions, such as soap bubbles and toys 
• Rapid injection (instead of slow)

Others have shown more mixed results:

• Topical cold sprays
• The Shotblocker
• Simultaneous instead of sequential shots
• Music
• Verbal suggestions of less pain (i.e., lying to your kid)

And these are the useless ones:

• Cartoon stickers  
• Coughing while getting a shot

Finally, have you ever considered leaving the room while your child is being poked?  My husband does it all the time, since he gets faint at the sight of a needle. One randomized, controlled trial of parental presence vs. absence found that having a parent in the room during immunization increases the level of "behavioral distress," particularly crying, in kids 4 and over.  There was no difference between the two groups in the average heart rate, suggesting there was no true difference in their levels of acute pain.  Despite the subjective signs of increased distress, when asked afterwards whether they would want their parent with them during future shots, 86% of the kids said that they would.  I love that there's proof that kids play to their audience, and yes, I admit, it does make me feel needed.

*Fear of needles

**Unfortunately, all of these RCTs are small and prone to publication bias (i.e., a small positive study is more likely to be published than a small negative one).  They are also plagued by lack of blinding, and placebos reduce pain an average of 30-40%.  You could argue, though, that since most of these interventions aren't harmful, you might as well use them for their placebo effect.

Protect the Girls -- Vaccinate the Boys!

 Mommy, why are we looking at hats for Siamese twins?

That's a photo of my then-5-year-old son J.J., shrinking in terror when I dragged him into Victoria's Secret.  Poor guy -- there's surely nothing more mortifying than bra shopping with your mom (unless it's bra shopping with your grandma). I do realize that one day, hopefully far in the future, my innocent little boy will have a very different reaction to all those scantily clad plastic torsos.  And when he reaches that age, it will be my husband's and my solemn responsibility to guide and protect him against STDs.  So naturally we'll be enrolling him in an abstinence-only sex ed program.*

Kidding, folks!  Remember, I'm Evidence-Based Mommy, not Delusional Mommy.

Last week, I reviewed the data on the HPV vaccine for girls.  In addition to cervical cancer and genital warts, HPV causes the vast majority of penile and anal cancers, although these are much rarer.  Gardasil has been FDA-approved for use in males ages 9 through 26.  So what is the evidence that it works in this population?  And now that J.J. is on the cusp of turning 9, should I be asking his pediatrician for this series of expensive shots?

As with the HPV vaccine trials in women, there are no large studies in preteens, but again, the idea behind immunizing children is to protect them before they are potentially exposed to the virus in their teens or young adulthood.  The largest trial randomized over 4000 males ages 16 to 26 to the 4-strain HPV vaccine vs. placebo.  ("Efficacy of quadrivalent HPV vaccine against HPV infection and disease in males.")  The marketing geniuses at Merck couldn't come up with a snappy acronym this time, but I liked my Scrabble-savvy friend's suggestion of SPAWN, for Stop Penectomies** and Anal Warts Now.  Six hundred of the participants reported having sex with men, a major risk factor for HPV infection.

As in the female trials, the vaccine was quite effective in patients who were uninfected at baseline, with an 84% reduction in genital lesions (mostly warts) in those who received all three shots.  The benefit in the population as a whole was significantly less, but still a decent 60% reduction.  Three precancerous penile lesions occurred in the placebo group and none in the vaccine group, but SPAWN wasn't large enough, or of sufficient duration, to detect a difference in these rare neoplasms.

Despite the clear benefit in reducing genital warts, the most frequent and more politically palatable argument for immunizing boys is to protect girls against cervical cancer.***  So should the HPV vaccine be mandatory in boys?  As much as I feel that males should shoulder some of the moral responsibility for their partners' health, in this case, I have to say no.  One of the reasons I've come to this conclusion is that cost-effectiveness analyses have shown that immunizing boys in addition to girls is extremely expensive, compared to immunizing only girls.  The excess cost ranges between $100,000 to a million dollars per year of life gained.****

Having said that, I do plan to sacrifice my eldest son on the altar of public health when his time comes.  Unfortunately for my human pincushion kids, I'm an allopathic doctor who is unabashedly pro-immunization.  Some day they'll thank me for it.

*Evidence has shown that abstinence-only programs are useless in delaying sex.  This is not to be confused with the seemingly oxymoronic abstinence-only parenting.  Telling your child, "Like hell you'll be crashing at your boyfriend's tonight!" has been shown to delay sex.
**A penectomy is an amputation of the penis, standard treatment for penile cancer.  If men were made aware of this, we would have no problem achieving 100% vaccination rates.
***For my gay readers, I apologize for this obviously hetero viewpoint.  There is a much more compelling argument to vaccinate gay males, as the incidence of anal cancer is similar to that of cervical cancer before the era of Pap smears.  The problem with vaccinating only gay males is that by the time a teenager or young adult is comfortable enough to come out of the closet, he may already be infected with HPV.
****Technically speaking, "quality-adjusted life-years" gained.  Since the most frequent manifestation of HPV infection are genital warts, and since warts don't kill you, researchers ask participants to estimate how many years of life they would be willing to give up not to have warts. One study found that having warts was as bad as losing anywhere from 1.6 to 8.3 days of life. ("Cost of treatment and QALYs lost due to genital warts.")  Hard to believe, but I guess I could see how it could get to be over a week if the warts made their cameo on, say, prom night.

Gardasil = Girls Gone Wild?

Stick to your guns, Governor Perry!

Four years ago, Texas governor Rick Perry raised a ruckus when he issued an executive order for all sixth-grade girls to undergo mandatory vaccination against the human papilloma virus, the cause of most cervical cancers and genital warts.  It was a strong and surprising move, especially coming from a politician who believes in teaching kids that cavemen coexisted with dinosaurs.  Critics from the right (and a few from the left) railed against the order, claiming it infringed upon parental rights and taught girls that premarital sex was O.K., despite the fact that the order gave parents the right to opt out of vaccination.  The order was overturned by the state legislature, and mandatory HPV vaccination never went through.  Now that he's running for the White House, Perry is apologizing for his earlier decision, stating, "I didn't do my research well enough."  Was he right then, or is he right now?  Well, Governor, how about if I do the research for you?

The landmark trial that got the HPV vaccine approved by the FDA was the "Females United  to Unilaterally Reduce Endo/Ectocervical Disease," Study, with the totally awesome acronym, "FUTURE II," bringing to mind a popular Disney attraction rather than genital warts.  ("Quadrivalent vaccine against human papillomavirus to prevent high-grade cervical lesions.")  Over 12,000 women ages 15 to 26 years were randomized to three doses of the HPV vaccine or placebo.  The vaccine was designed to protect against two HPV strains that cause 70% of cancers, and two other strains that cause the majority of genital warts.  The primary endpoint, which was carefully selected by Merck, maker of the vaccine, was the rate of cervical cancer or precancer caused by the two HPV cancer-causing strains in women who were not previously infected by these strains.  Got it?  Not the overall rate of all cervical cancer or precancer in all the women, but only a subgroup of cancers in a subpopulation.

The vaccine was extremely effective:  in women without prior infection, the vaccine prevented 98% of cancers and precancers caused by the two strains of virus, and almost 100% formed protective antibodies.  But what if you looked at the entire group of 12,000 women, and all forms of cervical cancers and precancers?  It turns out the efficacy was a disappointing 17%.

So why was the overall efficacy of the vaccine so low?  Two reasons:  First, the women who received the vaccine were still unprotected against the strains of HPV that cause the remaining 30% of cervical cancers.  Second, a good number of the women were already infected with the strains in the vaccine, rendering it useless.

So does that mean we shouldn't bother giving this expensive vaccine because of its low overall efficacy?  Actually, the results of the study strongly suggest that we should be giving the vaccine to girls before they become sexually active.  The CDC reported in 2006 that 70% of girls are sexually experienced by the time they are 19, and another study found that 27% of women aged 20-24 test positive for HPV.  If you follow the American Academy of Pediatrics' guidelines and give the vaccine to presumably uninfected 11- to 12-year-old girls, they should experience a 70% reduction in cervical neoplasms.  I suspect that pharmaceutical companies are probably working on adding more strains to the vaccine, to get the efficacy closer to 100%.

What about the argument that the vaccine will lead to a false sense of security, or an increase in early, sexually risky behavior?  Certainly, there are lot of misconceptions about the vaccine -- for example, that it protects against all cervical cancers, or that you can stop getting Pap smears.  The vaccine shouldn't be given without a fairly sophisticated discussion of the expected benefits.  Presumably, the discussion would be between the parent and the pediatrician, and then ideally, between the parent and the child.  I suspect that a big reason why some parents are reluctant to vaccinate their kids is that they want to avoid an uncomfortable conversation.

As for whether an STD vaccine would be, as one author put it, "a passport to promiscuity," there is very little data.  Four Scandinavian countries recently surveyed 65,000 women about their sexual behavior prior to the introduction of the HPV vaccine.   (Interviewing Swedish supermodels about their sexual proclivities: obviously the brainchild of some repressed male researcher!) They plan on re-surveying them after the vaccination campaign, to see whether it affects their behavior. ("Women's sexual behavior.  Population-based study among 65,000 women from four Nordic countries before introduction of human papillomavirus vaccination.")  HIV vaccine trials have not found an increase in sexually risky behavior among its participants, though many of them were high risk to begin with.  And one survey of adolescent girls found that only about 10% thought that getting the vaccine meant that they were old enough to start having sex.  ("Adolescents' beliefs about their parents' human papillomavirus vaccination decisions.") Frankly, I think most teenagers and young adults are more frightened at the prospect of pregnancy and HIV than they are of HPV, and I doubt the vaccine will do much to alter their behavior.

So should the vaccine should be mandatory in girls?  I say yes, as long as parents have the option to decline.  Making it mandatory would remove its stigma as "the STD vaccine," and countries that have instituted school-based HPV vaccination programs have much higher rates of immunization that those that haven't.  Remember that this wouldn't be the first mandatory vaccine for a sexually transmitted disease; the hepatitis B vaccine is required for elementary school enrollment in most states. 

I do understand the argument that it shouldn't be as compulsory as, say, the measles vaccine, since your child can't catch HPV just by sitting next to an infected person in class.  But if we wait until girls are old enough to consent to the vaccine themselves, it may be too late.  I've seen too many 30-year-olds die agonizing deaths from cervical cancer to let my daughter suffer such a fate.  Even more women have to deal with the infertility resulting from treatment of their cancer or precancerous lesions.  We parents do all that we can to instill our own values into our children, but at a certain point, we have to accept that they will make their own decisions, good or bad.

So man up, Governor Perry!  Apologize for your apology, do the right thing, and become the public health advocate every presidential candidate should be.

Next week:  The HPV vaccine for boys

The End of Chicken Pox?

Medical students are taught that chicken pox pox* are classically described as “dewdrops on a rose petal.”  How the textbook authors got from this:

to this:

is beyond me.  I suspect some dermatologist got a little carried away after taking a creative writing course.  Now, any Boomer mother would be able to diagnose chicken pox in her child without the use of a gardening manual.  But believe or not, there may soon come a generation of doctors who will be unable to diagnose chicken pox by sight alone – and that’s a good thing.  Why?  Because it means that the varicella vaccine is working.

Varicella zoster is the virus that causes chicken pox, and the vaccine has been given to kids in the U.S. since 1995.  The single-dose shot is about 85% effective in preventing chicken pox, and close to 100% effective in preventing severe cases (typically defined as a horrifying 500 or more skin lesions, or requiring hospitalization).  The journal Pediatrics recently published a report showing that the number of deaths due to varicella has dropped by almost 90%.  ("Near elimination of varicella deaths in the US after implementation of the vaccination program”)  In fact, the reduction in mortality exceeded that predicted by computer modeling when the vaccine first came out.

Now if you look at the vertical axis, you’ll see that the absolute number of deaths, even before the advent of the vaccine, has always extremely low.  Most kids who fall ill will do fine with a little chicken soup (or, in my family, chicken jook).  In EBM parlance, the number needed to vaccinate is 3 million kids in order to prevent one death.  But that’s not really why we get our kids vaccinated, is it?  It’s more to prevent the discomfort, inconvenience and lost productivity of a case of chicken pox.  Given that over 90% of today’s adults have been infected with chickenpox, and the 85% effectiveness of the vaccine, that’s a number needed to treat of about 2 to prevent human misery.  And that’s a pretty good number in my book.

One last observation:  Since 2006, pediatricians now give a second, booster dose of varicella vaccine.  The number of breakthrough infections with the 2-dose vaccine is even lower than with the 1-dose.  So if, in the future, your doctor fails to diagnose chicken pox in your child without ordering a blood test, don’t be too hard on him!

(*Sorry, I know that sounds like “woodchuck chuck.”)