Consuming Peanuts in Infancy Can Help Prevent Peanut Allergies

Photo: Wikimedia / public domain

Photo: Wikimedia / public domain

Food allergies are commonly misunderstood, so please bear with me while I first explain what food allergies are and are not. Various foods can cause all sorts of unpleasant effects. Most of these are not allergies. Allergies are only reactions caused by a specific antibody (called IgE) that results in hives, trouble breathing, or a life-threatening condition called anaphylaxis. So, if yogurt gives you diarrhea, that’s not an allergy. It might be lactose intolerance. If coffee gives you palpitations, you’re not allergic to coffee; you’re having a side-effect from the caffeine. Ditto chocolate worsening your heartburn; not an allergy.

Of all foods that cause allergic reactions, peanut allergies are the leading cause of anaphylaxis and death, and the prevalence of peanut allergies in the US has grown fivefold in the last 13 years, from 0.4% in 1997 to more than 2% in 2010. This increasing prevalence of a potentially life-threatening allergy has caused some schools to ban peanut products and has caused some airlines to stop offering peanuts in their snacks.

Believing that repeated exposure in infancy of allergy-causing foods leads to allergies, health officials in the UK in 1998 and in the US in 2000 published guidelines recommending the exclusion of foods likely to cause allergies from the diets of infants at high risk of developing allergies. But subsequent studies failed to show that elimination prevented the development of allergies, so the recommendations were withdrawn in 2008. Since then, pediatricians have had no solid evidence on which to base recommendations, until now.

A study in the UK published this week in the New England Journal of Medicine (NEJM) enrolled 640 infants between the ages of 4 and 11 months who were considered to be at high risk for peanut allergy because they had severe eczema or egg allergies, or both. They were all given a skin-prick test to check for peanut sensitivity. The infants that had a severe reaction to the skin-prick test were excluded from the study. Infants who had no reaction or a mild reaction were enrolled and were randomized to two groups.

The parents of children in one group were told that their children should avoid peanut products. The parents of children in the second group were instructed to give their children at least two grams of peanut protein three times a week. (Their first exposure to peanut protein was done under medical supervision.)

The peanut source given to the infants in the study was Bamba, an extremely popular Israeli children’s snack made from puffed corn and peanut butter. If you’ve spent any time in Israel around kids you’ve seen Bamba. Hilariously, the authors admit that “it was not possible to administer a placebo for Bamba because of financial and logistic constraints.” I can imagine the researchers desperately trying to figure out how to make something that looked and tasted like Bamba but without peanuts, and then giving up when they realized that that this would be more expensive and take longer than the rest of the study. The authors tell us that smooth peanut butter was supplied for those infants who didn’t like Bamba, but intensive psychiatric testing would have been more appropriate, because Bamba is delicious.

The children were followed until they were five years old and then given a supervised oral challenge of peanut protein to test them for allergies.

The results were quite dramatic. Among the children who initially had no reaction to the peanut sensitivity skin-prick test, 13.7% (about 1 in 7) of the children who avoided peanuts became allergic, compared to 1.9% (about 1 in 50) of children who consumed peanuts. That means that for every 8 children who consumed peanuts one fewer child developed a peanut allergy.

The results in children who initially had a mild reaction to the skin-prick test were even more impressive. These children were at much higher risk of becoming allergic since their mild skin test result suggests that their immune system had already been partially sensitized to peanut protein. 35.3% (about 1 in 3) of the children who avoided peanuts became allergic, compared to 10.6% (about 1 in 10) of the children who consumed peanuts. That means that for every 4 children with a mildly positive skin test who consumed peanuts, one fewer child became allergic.

Recommendations will likely be updated to account for these findings. First, infants with no eczema or family history of peanut allergies are at low risk of developing allergies and should start eating peanut products as soon as they start eating solid foods. (Don’t feed whole peanuts to infants. They’re a choking hazard. Anyway, Bamba tastes better and now might be one of the most evidence-based snacks.) Infants who are at high risk for peanut allergy because of eczema, an egg allergy, or a family history of peanut allergy should have a skin test to check for sensitivity to peanut. Those who have a negative test can proceed with Bambafication. Those who have a positive test should have their first exposure to peanut product under the supervision of an allergist.

Learn more:

Exposing infants to peanuts causes big reduction in peanut allergy, study shows (The Washington Post)
Feeding Infants Peanut Products Could Prevent Allergies, Study Suggests (Well, New York Times health blog)
About-Face on Preventing Peanut Allergies (Wall Street Journal)
The LEAP Trial (NEJM Quick Take video)
Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy (NEJM article)
Preventing Peanut Allergy through Early Consumption — Ready for Prime Time? (NEJM editorial)

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Marginal Exercise Advice From a Newbie

Albert finishing 10KI have lots of patients who are incredibly fit. I have patients who have run marathons. I have a patient who rides in rodeos. I have patients who have completed Ironman Triathlons. And I have lots of patients for whom exercise has always been a part of their routine, a lifelong habit. Though I hope they still enjoy it, this post isn’t written for them.

This post is for people who don’t exercise, for people who either hate exercise or have never done it with any regularity. This post is for people who haven’t made the leap from exercising zero times a week to exercising a couple of times a week. In short, this post is for people just like me until about a decade ago.

I’m going to try to get you off your couch.

If you’re anything like me you don’t care your biceps or abs look like. You don’t particularly pay attention to your body, and you assume that your body will return the favor. You make a living with your brain, which means that you drive a desk or a laptop all day. As a kid you never fell in love with sports and you were never much of an athlete.

Now, if you have some chronic medical problems, like diabetes, or high blood pressure, or high cholesterol, then your doctor has already harangued you about exercising to get your sugar, blood pressure and cholesterol down. But let’s assume you have the luxury of good health (for now).

I believe that what will get you exercising regularly are the mental benefits of physical activity. If you’re a pointy-headed geek like me you need to know that exercise will help you concentrate better and think more clearly. It will improve your sleep and your energy. If you do cognitive work for a living, the improved efficiency will more than compensate for the time spent exercising.

If you have psychological illnesses, you should know that exercise will lower your anxiety and stabilize your mood. That doesn’t mean it’s a substitute for medications, but it means that it can help the medications work. I’ve had countless patients tell me that they rely on exercise to help lift their depression, blunt their mania, and calm their anxiety. I know myself that there’s no better way to silence pointless ruminations about an unpleasant event than to climb a hill on my bike.

The only challenge is getting started and persevering until exercise becomes a pleasant habit. I promise you that it will happen. To that end, I have two bits of advice. But remember, I’m not a coach or a personal trainer. Most of my posts are full of links to double blind studies and reviews of data. This post is just the musings of a middle-aged guy who grew up not exercising and now actually likes it.

My first bit of advice is to find the cardiovascular exercise you hate least. Walking is a terrific choice. You can do it almost anywhere, and Los Angeles has gorgeous hikes and walks within short drives from almost anywhere. I love biking and swimming because I can do them alone or with friends. I don’t enjoy running (yet) but some patients and colleagues persuaded me to give running a try. I love the efficiency of it; you can put your shoes on, leave your front door, and have a very hard work out in 30 minutes.

My second bit of advice is to do some kind of exercise almost every day. Doctors will tell you to exercise three times a week to get the cardiovascular benefit. But it’s hard to have a three-times-a-week habit. We don’t do things three times a week. It’s much easier psychologically to do something every day, or at least every weekday. Then, it’s just like brushing your teeth or getting dressed or going to the office. It’s routine.

I know you don’t think you have time. I know when you have a stressful week you’ll be very tempted to skip exercise. But I also know that after a month you’ll look forward to it, you’ll feel better after you do it, and you’ll realize that the rest of your day is calmer, more focused and more organized because you force yourself to elevate your heart rate for 30 minutes daily.

Last weekend I ran my first race, a 10K. My time was abysmal, but my goal was only to run the whole thing without walking, and by that measure I succeeded. This is not bragging. Any serious runner has a much faster time on a 10K race than mine. It’s the opposite of bragging. It’s insisting that if I can do it, you can too.

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Expensive Placebos Work Better than Cheap Ones

Credit: Wikimedia, Creative Commons License

Credit: Wikimedia, Creative Commons License

The power of placebos has long been known. People who believe that they are taking an effective drug frequently feel better. In fact, prior to the discovery of penicillin, it is likely that the placebo effect accounted for much of the benefit of medical care.

A study published this week in the journal Neurology makes an interesting connection between the magnitude of the placebo effect and the medication’s perceived price.

The study enrolled 12 patients with moderate to severe Parkinson’s disease. They were told that they were going to be given two new injectable medications for Parkinson’s that increase dopamine levels. They were told that the medications were believed to work equally well, but because of differences in how they are manufactured one medicine costs $100 per dose while the other costs $1,500 per dose.

The patients were randomized as to which medication they received first – the cheap or the expensive one. The patients received objective measurements of their ability to move and other Parkinson’s symptoms before and after the medication dose. The measurements were made by people who didn’t know which medication the patient received. About four hours after the first medication they received the other medication, again with symptom measurement before and after.

What the patients didn’t know is that both injections were just saline, salt water without any active ingredient.

Not surprisingly, the patients improved after both injections. What was surprising was that the “expensive” placebo was much more effective than the “cheap” one. In terms of magnitude of effect, the expensive placebo was about halfway between the cheap placebo and the effect of levodopa, a Parkinson’s medication that actually increases dopamine levels in the brain.

The result would have been less surprising if the patients were told that the more expensive medicine was more effective, but they were told that they were thought to be equally effective and the difference in price was attributed to a difference in manufacturing. Still, apparently, we can’t help but fool ourselves into making “you get what you pay for” into a self-fulfilling prophecy. The patients expected a greater effect from the more expensive medicine and actually had more improvement in their motor function.

This may help explain why we spend so much on things we should know won’t help. It may explain the continued success of the vitamin and supplement industry and the preference of some patients for brand-name rather than generic medications. (Many of my patients boggle when I tell them that my family and I use generic medicines whenever possible.)

Students and fans of behavioral economics likely would have predicted the outcome of this study. Wines with more expensive price tags are known to taste better than the same wine with a cheaper price tag. In fact the whole art of wine tasting seems to evaporate when experts are blinded about what they are tasting. So we should definitely buy cheap wine (and then fool ourselves by putting big price tags on the bottles).

The clinical applications of this study are not obvious. It’s not ethical to deceive patients, so we can’t just start lying and telling them that their medicines are more effective or more expensive than they really are. But we are reminded again of the power of patient expectations. If we can honestly shape expectations, for example by educating patients about the proven benefits of a medicine, perhaps we can ethically allow our patients to benefit from the placebo effect.

And I’m now surer than ever that I’ll be able to cure more of you as soon as I double my fees.

Learn more:

‘Expensive’ placebos work better than ‘cheap’ ones, study finds (Los Angeles Times)
An ‘expensive’ placebo is more effective than a ‘cheap’ one, study shows (Washington Post)
Expensive Drugs Work Better Than Cheap Ones (Well, New York Times health blog)
Placebo effect of medication cost in Parkinson disease (Neurology article, abstract available without subscription)
Do More Expensive Wines Taste Better? (Freakonomics Radio)

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Mickey, Minnie, Measles

Sleeping Beauty’s Castle in Disneyland. Credit: Tuxyso / Wikimedia Commons

Sleeping Beauty’s Castle in Disneyland. Credit: Tuxyso / Wikimedia Commons

It’s a world of measles, a world of flu.
It’s a world of mumps and pertussis too.
It’s a world that we share,
but please stand over there.
It’s a small world after all.
— My new proposed lyrics for the ride It’s A Small World

In December I wrote that 2014 was a banner year for measles in the U.S.. Take a moment to read that post if you want a refresher on the symptoms and history of measles.

Well, gentle reader, if you were hoping that 2015 would be the year that humans make inroads against measles, I fear you’ll be disappointed. So far, it looks like 2015 will be a year in which unvaccinated people gather in large groups and get infected. We’ve had more measles cases in California in January than in all of last year.

As of Wednesday, the California Department of Public Health has counted 59 cases of measles in California this year. 42 of these cases, including 5 Disney employees, are associated with an initial exposure at the Disney amusement parks in Anaheim in December. It is known that subsequently some patients visited the parks in January while infectious.

Vaccination status is known for 34 of the 59 cases. 28 of the 34 were unvaccinated. Six were infants too young to be vaccinated. Health officials are still investigating multiple people who may have come into contact with known patients.

This outbreak has led the Department of Public Health to advise that unvaccinated people not visit crowded places with a large number of international visitors. That’s a reasonable start. Vaccinating everyone in line at It’s A Small World might be even better.

What to do if you don’t know if you’ve been vaccinated? If you were born before 1957 it’s safe to assume you’re immune, since virtually everyone in that generation was exposed to measles. Everyone else should have two doses of MMR. The first dose is usually given at 12 to 15 months of age, and the second at age 4 to 6.

If you’re not sure if you received both doses, your doctor can just give you another MMR dose, or she can check a blood test to see if you’re immune. When it comes to infectious diseases, wishing upon a star might not be enough.

Learn more:

Disneyland Measles Outbreak Hits 59 Cases And Counting (NPR)
Unvaccinated People Warned to Avoid Disneyland Resort (Wall Street Journal)
Measles advisory (California Department of Public Health)
Measles Makes a Comeback (my post in December)

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‘Tis the Flu Season

Graphic credit: CDC

Graphic credit: CDC

Ah, the joys of January 2! Bleary eyed employees return to work, holiday cards fill waste baskets, and everyone contracts influenza.

This year’s flu season has started earlier than expected and has already reached high numbers of flu cases in 36 states. California is not one of them, but that likely means we’re a couple of weeks behind the East Coast, not that we’ll be spared. In fact, this week I saw my first patient of the season who had a positive test for the flu, and Google Flu Trends suggests that the numbers of cases in Los Angeles just started to increase.

It’s too early to know whether this season will be worse than previous years. That largely depends on how soon the disease peaks and then declines. But this season has already caused more hospitalizations than usual and a large number of deaths. As of December 20, eighteen children have died of the flu.

Part of the reason for this season’s intensity is that the predominant virus strain circulating is H3N2, a strain that usually causes more hospitalization and deaths. To make matters worse, though this year’s vaccine includes the H3N2 strain, the virus has changed since the vaccine was made, making the vaccine an imperfect match for the circulating virus. Still, an imperfect match is better than none, and health officials still urge everyone over 6 months of age to get vaccinated. Remember, if you’re young and healthy getting the shot isn’t primarily about protecting yourself. It’s about making it less likely that you’ll transmit flu to a more vulnerable person that you come into contact with.

Please take a moment to review the Centers for Disease Control and Prevention’s (CDC) advice about what to do if you get the flu. It has a helpful summary of flu symptoms and treatment, as well as warning signs of severe illness. If you have a mild illness, please stay home. If you have severe illness or are at high risk of developing complications contact your doctor immediately. Antiviral medication works best if taken in the first 48 hours after the onset of symptoms. Let’s also all do our best to cover coughs and wash our hands frequently.

I wish you a happy and healthy year. Let’s hope this flu season peaks soon and that your first achievement of 2015 isn’t getting sick.

Learn more:

Severe Flu Cases on the Rise in U.S. (Wall Street Journal)
This season’s flu activity has reached the epidemic threshold, the CDC says (The Washington Post)
Teen’s death shows horror of flu epidemic (CNN)
Google Flu Trends for Los Angeles
The Flu: What to do if you get sick (CDC)
Weekly US Influenza Surveillance Report (CDC)

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Retrievable Stents Offer Improved Outcomes for Stroke Patients

A CT scan of the brain of a patient with a right middle cerebral artery stroke. Image credit: Lucien Monfils / Wikimedia

A CT scan of the brain of a patient with a right middle cerebral artery stroke.
Image credit: Lucien Monfils / Wikimedia

There are few illnesses as disabling as a stroke. A stroke is the cessation of blood flow to part of the brain. It can cause sudden difficulty speaking, difficulty moving a limb, facial drooping, or the loss of vision in a fragment of the field of view. In many stroke patients the loss of function never improves and the patients remain permanently disabled.

Before the 1980s there was no effective treatment for this devastating illness. Stroke patients were simply observed and given physical therapy. Some improved, and many didn’t. In the 1980s a blood clot dissolving medication called tissue plasminogen activator (tPA) began to be used for stroke patients with encouraging results.

tPA is given intravenously and has to be given within 4 hours of symptom onset. In patients with small clots who present to the emergency department in time, it can make a dramatic improvement in outcome. In the 1990s a large study proved that treating stroke patients with tPA is better than not. The main limitation of tPA was the narrow time window and its lack of effectiveness against large clots in large arteries.

By the late 1990s many large stroke centers were trying to improve on tPA. At UCLA, where I trained, stroke patients were treated by inserting a catheter in the clotted artery and delivering clot-dissolving medications directly to the clot. That became the standard of care at many centers, though there were never large studies to show that this was better than intravenous tPA.

More recently, various devices have been designed to remove blood clots from brain arteries. But again, there has never been evidence that these are more effective than intravenous tPA, until now.

A study performed in the Netherlands and published online this week in the New England Journal of Medicine (NEJM) attempted to determine the best treatment for stroke patients who have large clots in large arteries. These are the patients at greatest risk of serious permanent disability. The study randomized about 500 such patients into two groups. Patients in one group received usual care, which for the vast majority meant intravenous tPA. Patients in the second group received intravenous tPA and an attempt to remove the clot from the artery. In most of the patients this was done with a retrievable stent, a wire cage that is pushed through an artery, envelops the blood clot, and allows the stent and clot to be pulled out of the artery. This treatment can be performed as late as 6 hours after the onset of symptoms.

Ninety days later 33% of the patients in the group randomized to clot retrieval were functionally independent, compared to 19% of the patients in the group that only received tPA. That means for every 7 patients that receives clot retrieval in addition to tPA one additional person is functionally independent 3 months later.

Note that even though the patients in the clot retrieval group did better, even in that group two thirds of the patients were not functionally independent at 90 days. That means they needed assistance for their activities of daily living. That is a sobering reminder of the poor outcomes that await most patients with large clots in large arteries.

There was no difference in mortality or severe bleeding between groups. The group receiving clot retrieval did have an increased risk of another stroke within 90 days, but this risk was numerically smaller than the improved functional independence. This NEJM Quick Take Video summarizes the findings of the study.

So stroke is more treatable now than ever. But the time from the onset of symptoms to the initiation of therapy is still critical for a good outcome. So if you ever suddenly develop difficulty speaking, or can’t move a limb, or lose vision in a fragment of your field of view, call 911. Getting to an emergency room promptly can make the difference between getting 1970s care for your stroke and getting 2014 care.

Learn more:

For First Time, Treatment Helps Patients With Worst Kind of Stroke, Study Says (New York Times)
Stents Boost Stroke Recovery, Study Finds (Wall Street Journal)
Clot-grabbing devices offer better outcomes for stroke patients, study finds (Washington Post)
Video: MR CLEAN (NEJM Quick Take)
A Randomized Trial of Intraarterial Treatment for Acute Ischemic Stroke (NEJM, subscription required)
Interventional Thrombectomy for Major Stroke — A Step in the Right Direction (NEJM editorial, subscription required)
The Stroke – Billy Squire (YouTube)

Tangential Miscellany

Happy Hanukkah, Merry Christmas, and a joyous and healthy 2015!

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Measles Makes a Comeback

The rash caused by measles. Credit: CDC/ Heinz F. Eichenwald, MD

The rash caused by measles.
Credit: CDC/ Heinz F. Eichenwald, MD

I haven’t written about measles in over two years, but unfortunately it’s in the news again.

Measles is a very contagious viral illness that causes a high fever, rash, cough, and a runny nose. Complications include pneumonia, brain inflammation and death. Prior to 1963 there were hundreds of thousands of measles cases in the US annually, causing hundreds of deaths. In 1963 the measles vaccine was introduced, leading to an immediate decrease of measles cases in this country.

In 2000 measles was declared eliminated from the US. That means that for at least 12 months there was no person-to-person transmission of measles in the US, and any cases in the US were acquired by travelers abroad. But since then, instead of progressive global elimination of measles, we’ve had several setbacks.

In 2012 I wrote that there were 222 cases of measles in 2011, the highest number since 1996. This year that number doesn’t seem so bad. From January to October 2014 there have been 603 cases in 22 states, including California. There were 20 outbreaks during that time, meaning episodes in which person-to-person transmission is occurring in the US. The majority of the cases were in unvaccinated people.

In January to April of this year there were 58 confirmed measles cases in California, including 22 in Orange County and 10 in Los Angeles County. Of them, the vast majority were linked to recent travel abroad. Most of the patients were either unvaccinated or had no vaccination documentation available.

The problem is that vaccination has been a victim of its own success. Before 1963 everyone knew lots of people who had measles, and everyone heard of some people who had terrible complications. The case for vaccination was obvious and universally understood. But with nearly universal vaccination, public understanding of the risk of measles has waned and increasing numbers of parents are choosing not to vaccinate their kids. Add to that a scurrilous and fraudulent campaign to link vaccines with autism (a link that has been debunked repeatedly) and you have the perfect milieu for reversing decades of life-saving progress.

These numbers have much to teach about how vaccines work and how they don’t work.

First, though most of this year’s measles cases were unvaccinated, a minority of the cases were people who had documented vaccinations. That means that vaccines, like any other preventive medicines, aren’t perfect. Some vaccinated people will not develop protective immunity and will remain susceptible. In addition, some kids can’t be vaccinated for medical reasons. That means that even in an ideal world in which everyone who can be vaccinated is vaccinated, a small fraction of the population remains susceptible to infection.

So how was transmission ever eliminated?

It’s the number of susceptible people, or rather their fraction of the population, that matters. Below some critical number, each susceptible person comes into contact with people who are all immune, making person-to-person transmission very unlikely. But above that critical threshold there are enough susceptible people to sustain a chain reaction of infection.

The scary conclusion is that I can’t be sure I’ve protected myself by being vaccinated. I’m protected when most people around me are vaccinated, and I contribute to their protection by being vaccinated myself. If parents’ refusal to vaccinate their kids only endangered them, we might only raise our eyebrows in disapproval. But their refusal endangers our kids too.

Learn more:

The Measles Outbreak Coming Near You (Wall Street Journal)
Wealthy L.A. Schools’ Vaccination Rates Are as Low as South Sudan’s (The Atlantic)
O.C. measles outbreak spurs officials to call for immunizations (Los Angeles Times)
Measles (Centers for Disease Control and Prevention)
Notes from the Field: Measles — California, January 1–April 18, 2014 (Morbidity and Mortality Weekly Report)

Some of my previous posts about measles:

Measles Cases in 2011 Highest in Fifteen Years (2012)
Study Linking Vaccines to Autism not Just Wrong, Intentionally Fraudulent (2011)
U.S. Measles Cases at Highest Numbers Since 2001 (2008)

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Thank You Very Much

Image credit: Jim/Wikimedia, Creative Commons license

Image credit: Jim/Wikimedia, Creative Commons license

Tomorrow I expect to sit with my extended family at my sister’s house and consume copious quantities of yummy food. After that, my and her kids will destroy her house in cute ways that will delight the grandparents. Good times.

That in itself is a reason for gratitude. Given the fact that most humans who have ever lived spent every winter nearly starving to death, the abundance of food and material comfort at our disposal is nothing short of miraculous. And the fact that we’re all healthy enough to get together to celebrate is a true blessing.

But I would be remiss if I headed off to celebrate without thanking you.

To my readers: I’m grateful for all your feedback, for pointing me to interesting stories, and for forwarding my posts on social media. It’s largely because of you that my posts have appeared on KevinMD, American College of Physicians Internist blog, The Jewish Journal, and other publications. I know my blogging has been very intermittent this year. Patient care will always come first, but I promise to keep trying to inform you.

To my patients: I’m so thankful to you for the trust you place in me. Some of you have had serious illnesses this year and it’s been an honor and a privilege to guide you through such trying times. It’s a blessing to simply make a living, but I have the double blessing of getting paid to do what I love. I owe that to all of you. And because so many of you mentioned me to your colleagues and loved ones, this year is my best so far. Thank you very much. I promise to do my best to keep you healthy.

As is my tradition, I hereby lift my patients’ dietary restrictions for one day. Of course, I can’t suspend the laws of biology. If you take your dietary indiscretion too far, I’ll probably hear about it from your local emergency department. I hope you are able to gather with loved ones and energetically attempt to enumerate your countless blessings.

Happy Thanksgiving!

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A Second Vaccine against Pneumonia Recommended for Seniors

Streptococcus pneumonia bacteria grown from a patient’s blood culture. Credit: CDC/Dr. Mike Miller

Streptococcus pneumonia bacteria grown from a patient’s blood culture.
Credit: CDC/Dr. Mike Miller

If you’re over 65, there’s a new vaccine you should know about.

But before I explain the vaccine, let me introduce you to the bacterium that the vaccine protects you from. The little blue ovals in the above picture are Streptococcus pneumoniae bacteria. You might have guessed by its name that S. pneumoniae is a leading cause of pneumonia, and you’d be right. Pneumonia is an infection of the lungs, usually manifested by fever, productive cough, and shortness of breath. Pneumonia can be caused by bacteria, viruses, and fungi, but S. pneumoniae is such a common cause of pneumonia that it’s nicknamed the pneumococcus – the coccus (little round bacterium) that causes pneumonia.

The Centers for Disease Control and Prevention (CDC) estimate that 900,000 people in the U.S. contract pneumococcal pneumonia every year, and tens of thousands of them die. Pneumonia is usually treated with antibiotics, but some strains of the pneumococcus have developed resistance to some drugs. If that wasn’t bad enough, S. pneumoniae can also cause bloodstream infections and meningitis, which are even more life-threatening than pneumonia.

Given the severity of pneumococcal illness in people over 65, prevention in this age group has been critical. For over 30 years a pneumococcal vaccine called Pneumovax 23 has been recommended for everyone 65 and over. (The generic name for Pneumovax 23 is PPSV23, 23-valent pneumococcal polysaccharide vaccine. You don’t need to know that for the test. I’m just mentioning it here because you’ll see that name in other articles. Oh, and there is no test.) Pneumovax 23 protects against 23 different strains of S. pneumoniae but the immune response it stimulates in patients is just meh. That’s good enough to protect against bloodstream infections and meningitis, so it still saves many lives, but the evidence that it prevents pneumonia isn’t very strong.

A newer vaccine against the pneumococcus appeared in 2010. It’s called Prevnar 13 (PCV13, 13-valent pneumococcal conjugate vaccine). It has been used since that time in vaccinating children. It only covers 13 strains of pneumococcus but it stimulates a much stronger immune response than Pneumovax 23. Interestingly, there is some evidence that immunizing children against the pneumococcus has led to fewer pneumococcal illnesses in older people since there are fewer sick kids around to infect them. This is another bit of evidence of a phenomenon called herd immunity – immunizing some members of a “herd” protects the rest of them just because there are fewer vulnerable members to transmit the disease.

Recently Prevnar has been tested in and approved for use in seniors. A recent study showed definitively that it helps protect from bloodstream infections, meningitis, and pneumonia caused by the pneumococcus. Last month the CDC recommended Prevnar in everyone 65 and older.

Because Pneumovax 23 covers more strains, seniors should now receive both vaccines, not just the new one, but because the two vaccines protect against some of the same strains, they can’t be given at the same time. Here’s the recommended timing.

  • People 65 and over who haven’t received either vaccine should first receive Prevnar 13 followed 6 to 12 months later by Pneumovax 23.
  • People 65 and over who have already received Pneumovax 23 since they turned 65 should receive Prevnar 13 at least a year after receiving Pneumovax 23.
  • People 65 and over who have already received Pneumovax 23 before turning 65 should receive Prevnar 13 at least a year after their most recent Pneumovax dose, and then should receive another dose of Pneumovax 6 to 12 months after the Prevnar but not earlier than 5 years after the last Pneumovax dose.

Got that? If not, this handy box illustrates the options nicely. The good news is that you can get the flu vaccine at the same time as either pneumococcal vaccine, so you’ve got that going for you, which is nice.

So if you’re 65 or older make sure that you get both Pneumovax and Prevnar in whichever order is appropriate for you. And if you’re younger, make sure your parents and aunts and uncles get the news. Because you don’t want the above picture to be the blood culture of someone you love.

Learn more:

Some Good News on Pneumonia (New York Times, The New Old Age blog)
New Advice for Vaccines to Stave Off Pneumonia (Wall Street Journal)
Pneumococcal Vaccination (Centers for Disease Control and Prevention)
Use of 13-Valent Pneumococcal Conjugate Vaccine and 23-Valent Pneumococcal Polysaccharide Vaccine Among Adults Aged ≥65 Years: Recommendations of the Advisory Committee on Immunization Practices (ACIP) (Morbidity and Mortality Weekly Report)

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Sorting Out the Different Flu Vaccines

A sailor receives a flu shot. Credit: US Navy

A sailor receives a flu shot. Credit: US Navy

The best way to avoid the flu is spending the months from fall until spring in a solitary bunker, communicating with other people only electronically. The second best way is getting the flu vaccine. The Centers for Disease Control and Prevention (CDC) recommends the flu vaccine for everyone over 6 months who doesn’t have a specific contraindication to it.

Because of the increasing number of different flu vaccines that are now available, this post highlights the three most commonly used flu vaccines, their indications and side effects.

Inactivated Standard-Dose Injectable Vaccine
This is the standard flu shot. It is approved for adults of any age and for children 6 months or older. It is recommended for pregnant women and for people with chronic illnesses, both of whom are at increased risk of serious complications from the flu. It is more effective in adults than the intranasal live-attenuated vaccine.

Side effects from the flu shot are very rare except for soreness and redness at the injection site. The vaccine contains no live virus, so the common misconception that the flu shot can cause flu-like symptoms is just that.

Intranasal Live-Attenuated Influenza Vaccine (FluMist)
This vaccine is a nasal spray. It is approved for healthy, non-pregnant people 2 to 49 years of age. It’s more effective than the inactivated vaccine in children 6 years old or younger. Because it contains a live virus, it should not be taken by pregnant women, patients with weakened immune systems, people with respiratory illnesses, or caregivers of severely immunocompromised patients.

FluMist can cause runny nose, nasal congestion, and sore throat.

Inactivated High-Dose Vaccine (Fluzone High-Dose)
Older people are at highest risk for complications for the flu, so they have potentially the most to benefit from vaccination. But ironically older people have immune systems that have the weakest responses to vaccines. For this reason, a vaccine with a higher dose was produced. Fluzone High-Dose has four times as much antigen from each flu strain as the regular vaccine. It’s basically just like getting four standard flu shots but in the same injected volume as one shot. It is slightly more effective in preventing flu than the standard vaccine. In a randomized trial trial 1.4% of older adults who received the high-dose vaccine later developed flu compared to 1.9% of those who received the standard-dose vaccine. That means that for every 200 older adults who take the high-dose vaccine instead of the standard-dose, one case of flu is prevented. Fluzone High-Dose vaccine is approved for adults 65 years and older. This group of people can also opt for the standard vaccine.

Fluzone High-Dose causes more injection-site reactions than the conventional vaccine but no increase in serious adverse effects.

The CDC influenza vaccination page has a lot more information about each vaccine and more specific contraindications.

So figure out which vaccine is right for you and get it. Our office only carries the inactivated standard-dose shot, but the others are available at many pharmacies. After protecting yourself you can come out of your bunker, or invite friends over. I’ll bring snacks.

Learn more:

Vaccination: Who Should Do It, Who Should Not and Who Should Take Precautions (Centers for Disease Control and Prevention)
Google Flu Trends for Los Angeles
Efficacy of High-Dose versus Standard-Dose Influenza Vaccine in Older Adults (New England Journal of Medicine, by subscription only)
Influenza Vaccine for 2014-2015 (The Medical Letter, by subscription only)

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