The pneumonia vaccine (Prevnar-7®) is a relatively new addition to the immunization schedule for infants and children. Even though many people call it the pneumonia vaccine it actually protects children against meningitis, blood infection, ear infection, and pneumonia. In the U.S. the recommended schedule is 4 doses. One at 2, 4, 6 months and a booster at 12-15 months.
Understanding the Pneumonia Vaccine
Streptococcus pneumoniae
This is the fancy name for the type of bacteria that the vaccine is designed to protect against. To make things simple many just call it pneumococcus. Pneumococcus is common in the community and many of us have this bacteria in our nose and mouth. In most cases we do not even know we have it because it does not cause any problems. Sometimes it can cause infection. Most infections are minor and easily treatable (like ear infection). Rarely, it can lead to a serious infection like pneumonia or meningitis.
Nasopharyngeal carriage
This is the fancy medical term that means you carry the bacteria in your nose or mouth but it is not causing infection. Years of research has shown that the first step to getting an infection with pneumococcus is carrying the bacteria in your nose or mouth. Then, when the time is right (like if you get a cold) the bacteria may cause an infection. Thus logic dictates that if you can reduce the number of people who are carriers of pneumococcus then you can reduce the number of infections it causes. Further, by reducing the number of people who are carriers, you may also indirectly reduce the spread of pneumococcus to others, again reducing the number of infections that it causes.
Lots of different types
There are around 100 different types of pneumococcus. We call each one a serotype. Each serotype is unique. Immunity to one type does not mean that you have immunity to the others. Each serotype tends to have a specific pattern of antibiotic sensitivity. Some serotypes are very resistant to antibiotics. Other serotypes are sensitive to most all antibiotics.
Not all serotypes cause the same type of infection. Some are more likely to cause Invasive Pneumococcal Disease (IPD). This means serious infection – like pneumonia, blood infection, or meningitis. Others are never associated with invasive disease.
The Pneumonia vaccine is designed to protect against the 7 worst serotypes of pneumococcus. The 7 that are the most resistant to antibiotics and most likely to cause invasive disease.
Alternative Dosing
The European study
There was a recent study published in the Journal of the American Medical Association (JAMA) that looked at using a reduced number of Prevnar® doses. They compared three groups:
- Two doses given at 2 and 4 months.
- Two doses given at 2 and 4 months plus a booster dose at 11 months.
- Nothing (a control group)
The endpoint was how many patients carried one of the bad pneumococcus strains at 12, 18 and 24 months. In other words, how many patients were nasopharyngeal carriers despite getting the vaccine. The did not look at invasive disease between the three groups.
The results
The baseline carriage rate of pneumococcus is just under 40%. Thus in this study the researchers checked the patients at 12 months, 18 month, and 24 months.
- In the 2 dose group, the carriage rate was 25%, 24%, and 15%.
- In the 2 + 1 dose group, the carriage rate was 20%, 16%, and 14%.
- In the control group, the carriage rate was 38%, 36%, 36%.
Thus from the information above it is clear that the vaccine does reduce nasopahryngeal carriage of pneumococcus. The more doses you get the better during the vulnerable ages between 12 and 18 months. However as children approach 24 months the benefit of using the 2 dose versus the 2+1 dose looks about the same (at least from the standpoint of nasopharyngeal carriage of pneumococcus).
What We Do in the US
We give 4 doses in the US (one dose at 2, 4, 6 months plus a booster at 12-15 months). I cannot find any studies that compare a 2 dose, or 2+1 dose regimen to what we do here in the U.S. What I can find though is what happens to kids that get the 3+1 regimen that we give in the U.S.
Impact on invasive disease
Overall Impact
The U.S. regimen has been well studied with respect to the impact on invasive pneumococcal disease (IPD) like pneumonia, meningitis, blood infection, etc. When you look at vaccine type-invasive pneumococcal disease (VT-IPD) the vaccine effectiveness is 80%. This means that those who get the vaccine are 80% less likely to get the disease. Even more impressive, the vaccine appears to offer some protection against non-vaccine types as well. The vaccine effectiveness against all types of IPD is 58%.
Here is a chart that summarizes some of the studies looking at the impact of the vaccine on invasive pneumococcal disease (IPD)…
Impact on Meningitis
The invasive disease that is of most importance from my perspective as both a parent and a physician is pneumococcal meningitis. This is a devastating illness. It tends to affect otherwise healthy babies. Between 5 and 10% of cases will result in death. Those who survive are often left with severe neurological injury. If there is a way to prevent this disease, it make good sense to do so.
Fortunately for kids in the Western world it is very uncommon. In the U.S. it happens to about 1 in 100,000 kids. In other western countries it may be as high as 1 in 10,000. Either way it is pretty uncommon. In virtually all countries that have implemented a program of pneumococcal vaccination the rate of pneumococcal meningitis decreased by about 60%.
Of course the question that some may ask… Do we need to vaccinate 100,000 kids in an attempt to prevent 1 cases of meningitis?
If you have seen kids with bad pneumococcal meningitis the answer to this question is obvious.
Why we give a 4th dose in the U.S.?
I can find no data on the benefits of the 4-dose regimen we use in the U.S. versus the reduced-dose regimens (2 or 2+1). What I do find is the theoretical reason to give a booster dose at 12-15 months and the data that support this approach.
You can actually measure the antibodies (disease fighting proteins in your blood) against pneumococcus. When researchers measured these protein is kids aged 12-15 months the levels were not very high. They found that the levels could be “boosted” considerably by giving the “booster” dose at 12-15 months. Since this is still a high risk age for kids it made good sense to do so. Thus the 4th “booster” dose was born. The chart below highlights this affect. The pink bars are the antibody levels before the booster dose and the blue bars are the antibody levels after the booster dose.
2, 2+1, or 3+1 ?
From everything I have read it seems reasonable to use a reduced dose series for children. In fact many countries in Europe and other places have already implemented a reduced-dose regimen. There is no doubt that some of the vaccine is way better than none vaccine. The benefit of 2 versus 3 versus 4 doses is unclear. So for parents looking to vaccinate but wanting to minimize the number of vaccines in the safest way possible, I see no reason why a 2 or 2+1 regimen would be irresponsible.
The Problem
Many states have not caught up with the newest studies. Thus the CDC recommends, and most states require, 4 doses. When it comes to daycare and entering school the rules are complicated and vary from state to state. For example in one state I have worked (Iowa) a savvy parent could make the 2+1 regimen work by giving 1 dose at 2 & 4 months and then a booster at 12 months. This would be a 2+1 regimen and it would still fit within the daycare guidelines of the state.
Texas on the other hand has a different set of rules. The only way to make a 2 or 2+1 regimen work is to delay the first dose until the child is > 7 months. Waiting this long to give the first dose may allow for a reduced-dose schedule but it puts your child at risk from the disease. From birth to 7 months is the most vulnerable time for your child and waiting until 7 months is not a good idea in my opinion.
Want to know the rules in your state?
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What We Did For Our Son
Serious infection with pneumococcus is not good. Meningitis is particularly bad. I have seen a handful of kids with this in my career. One in particular I remember had terrible meningitis and ended up having a stroke. This baby survived but only with severe neurological disability. Pneumonia, on the other hand, is much more common, although with current technologies it is rarely fatal. This is not to say though that the consequences of pneumonia in small children are insignificant. For me, if my child got one of the invasive forms of the disease covered by the vaccine, I would have a hard time reconciling this outcome with my parental responsibility to protect him against serious threats to his well-being.
For me and my family, we gave one dose at 2, 5, and 11 months. We plan for a booster dose before going to daycare. So we conformed to the 3+1 regimen recommended by the CDC and required by most states. In retrospect, if we could make it work within the state requirements, we may have considered the 2+1 regimen. To do this we would have given 2 doses in the first 6 months and then a booster after 12 months.
Why Some People Choose Not To Give This Vaccine
Aluminum
Many people worry about the aluminum added to the vaccine. There is no doubt that Aluminum is toxic in high amounts. However, the body rapidly rids itself of aluminum with the kidneys. Thus for most kids with normal kidneys there is no reason to be concerned that the aluminum in the vaccines will be around for very long.
Researchers have studied the potential impact of aluminum in vaccines and have been unable to find any association with any long-term adverse consequence. In February of 2004 a group of scientists published a report in The Lancet (one of the most respected international medical journals) looking at virtually every study ever conducted regarding aluminum in vaccines. Their conclusion is not surprising…
We found no evidence that aluminum salts in vaccines cause any serious or long-lasting adverse events.
That said, if you look hard enough you can find all kinds of reports about all kinds of things caused by aluminum. Most are ridiculous but some are more credible. As I have mentioned before though, the potential risk of the vaccine must be weighed against the real risk of getting the illness.
For parents concerned about aluminum, it makes sense to me to space out those vaccines that contain aluminum. Since 50-75% of the aluminum in the vaccine is excreted by the kidney in 24 hours, allowing a few weeks or a month between each aluminum containing vaccine should be both safe and responsible.
You and Your Pediatrician
At the end of the day vaccination is complicated. The CDC recommended immunization schedule is the government’s attempt to make a one-size-fits-all plan for the vaccination of children. To that end it is very effective. Whimsical deviation from this schedule is dangerous, for both your children and those around your children. Well researched and well thought out deviations that are mindful of risks and benefits, make sense in some cases. Make sure you consult with your child’s physician when making these choices for your child. If you find the physician uninformed and unwilling to have this discussion – find another doctor.
Stay Informed
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References
CDC schedule – here is a link to the recommended immunization scheduled for infants and children.
JAMA Reduced Carriage – Here is a link to the article looking at the benefits of a reduced dose regimen of the pneumonia vaccine.
Pneumococcus Review – Here is a review article that covers this topic in way more detail for those who may be interested.
Pediatrics Article – this is an article that shows the impact of the current US 4-dose regimen on nasopharyngeal carriage.
Cochrane Review – the is a review article looking at the overall impact of Prevnar in the US.
The Lancet – this is the article looking at the impact of Aluminum in vaccines.
