Pneumonia Vaccines

First of all, there is no such thing as a “pneumonia” vaccine. The vaccines which prevent pneumonia are directed against a single bacteria called Streptococcus pneumoniae. Because bad actors often get nicknames, like “Billy the Kid” or “Bugsy Siegel,” this bacteria is also called “strep pneumo” or “pneumococcus.” The name sure sounds like pneumonia, but pneumococcus also causes meningitis, sepsis (bacteria in the blood stream), ear infections, and less often infections in the heart, joints, bones, and internal organs. There are more than 90 different strains of pneumococcus, although most disease is caused by about two dozen of them. Having immunity against one strain does not protect you against the others.

Pneumococcus lives in the nose of infants and young children. If you put a cotton swab up the nose of a healthy 1 year old, about 50% of the time you’ll find pneumococcus in there. Various strains of the pneumococcus bacteria take turns living in a kid’s nose. Sometimes, when a child acquires a new strain, he or she develops an ear infection a few weeks later. One strain might live in there for six months only to be replaced by another. In adults, the rate of colonization is lower, but you can still find pneumococcus living in about 3 percent of healthy adult noses as well.

We’ve had a pneumonia vaccine since the 1970s, but we never gave it to infants. The reason, as any Hollywood celebrity will tell you, is that vaccines cause autism. Ok, just kidding. The real reason is that the pneumonia vaccine we’ve been giving to people at age 65, called the Pneumovax, and more technically the PPSV23, does not produce a good antibody response in children. Children get a different vaccine, the PCV13, which does produce a better immune response.

The Pneumovax, or PPSV23 is a vaccine made up of certain molecules sitting on the outside of 23 different strains of pneumococcus. PPSV stands for Pneumococcal Poly-Saccharide Vaccine. What is a polysaccharide? “Poly” means many, as in “My friend from Utah is Poly-amarous” and “Saccharide” means sugar. Think of these as little sweet tasting molecules of corn starch to get an idea of what they are like chemically. In this vaccine, the little starch molecules are injected into someone’s arm and we hope the body will respond by making antibodies against these molecules. Then, when the pneumococcus tries to invade the body, we have a ready supply of antibodies that will stick to the bacteria. If you’re a bacteria floating around the body and you have a bunch of human antibodies stuck to your surface, well, you’re going to be eating by a white blood cell very quickly.

Vaccines made up of sugar molecules don’t work in young kids. The reason should be obvious. Kids like sweets. If they readily made antibodies against pneumococcal polysaccharide antigens, they might make antibodies against M & M’s, Starburst, or even Three Musketeers. That would be tragic. Ok, not really. The reason why this vaccine does not produce much of an immune response in children is not known, but given how much illness is caused by pneumococcus, researches tried to find a way to create a vaccine that would stimulate an immune response in infants.

The vaccine they came up with is the PCV13, sold under the brand name “Prevnar.” PCV stands for Pneumococcal Conjugate Vaccine. It’s the same polysaccharide, or sugar molecules, but only 13  strains this time. The key difference is the word “Conjugate.” Here, conjugate does not mean conjugate as in conjugating a verb (I walk, Bill walks), or as in conjugal visits in prison, but as in “joined to.” Let’s take a moment to review. The “Pneumonia” vaccine is not really directed against pneumonia, but against a specific bacteria, streptococcus pneumoniae, of which there are 90 different strains. One vaccine, PPSV23, Pneumococcal Polysaccharide Vaccine, sold under the brand name “Pneumovax” is for adults and consists of sugar molecules that sit on the outside of the pneumococcus from 23 strains of the bacteria. The other, PCV13, Pneumococcal Conjugate Vaccine, sold under the brand name “Prevnar” was originally marketed for kids and has those same sugar molecules, although only 13 strains, but now conjugated (means exactly the same thing as “joined to”) an immune booster that makes the body react more strongly to the vaccine.

What about that immune booster? Since injecting kids with sugar molecules was not getting the attention of their immune system, the sugar molecules were joined to something very noxious, the toxin produced by the bacteria which causes diphtheria. Ok, it is not really the diphtheria toxin, but something that looks almost exactly like it to the body. Conjugate vaccines are vaccines where the part of the bacteria or virus we want to protect against is bound to a very scary and obnoxious substance in order to stimulate a better immune response. PCV13 has been very effective in reducing the rates of pneumococcal infections in young children. PCV13 probably saves 50,000 young children every year from a pneumonia hospitalization.

Strictly speaking, you don’t need a

prescription to get this vaccine, but it avoids

confusion and assures you that you will get the

PROPER vaccine.

The immune response to PCV13 is so robust that not only does the body produce antibodies against these 13 strains of strep pneumoniae, but it also produces a series of cells whose sole purpose is to find and kill pneumococcus. If you stick a swab up the nose of the kids who have been immunized with PCV13, you don’t find those strains of pneumococcus living in there. The PPSV23 cannot do that.

In fact, PPSV23 (Pneumovax) does not produce that strong an immune response in adults either. Many older patients don’t get much protection from it, although some do. If the PCV13 vaccine is so effective in kids, why not give it to adults? Consider a public health strategy where we give adults the PPSV23, aka the Pneumovax which will give broad coverage to many strains, but then also give the PCV13 to get an even stronger immune response to the 13 worst strains with the PCV13. This is the basis of the new pneumonia vaccination guidelines. Give both vaccines to all adults 65 and over. Healthy people outside of childhood and before age 65, rarely have serious infections with pneumococcus, so this group is not targeted for vaccination, but in patients with asthma, alcoholism, and certain other chronic diseases at any age, one or both vaccines may be of benefit.

So we have two vaccines, both with “P” and “V” and a number in their names, both described as “pneumonia” vaccines to the public. The opportunity for confusion is significant. In addition, we can’t just give both together. Giving the PPSV23 (Pneumovax) with the PCV13 (Prevnar) results in a reduced immune response to the PCV13 vaccine for unknown reasons. Current guidelines say give the PCV13 and wait at least 8 weeks before giving the PPSV23 (Pneumovax). Or, give the PPSV23 and wait one year to get the PCV13 (Prevnar). Here’s some more confusion. Many hospitals just give people the PPSV23 (and flu shots by the way) without checking to see if the patient already had the vaccine. If you are a patient in our practice, 65 or older, I recommend you get the PCV13 (Prevnar) vaccine at your pharmacy. We are not able to get PCV13 in sufficient quantities for the practice. But do call or email the office and let us review your immunization history. We will generate a prescription and send it to you.

Strictly speaking, you don’t need a prescription to get this vaccine, but it avoids confusion and assures you that you will get the proper vaccine. Also, if you are a patient on an immune suppressive drug (Enbrel, Humira, etc), or if you are missing your spleen, you should also get the PCV13 (Prevnar) even if you are under 65.