Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.
In prior chapters, we touched on some of the unfounded claims that the anti-vaccine community makes about vaccines, medical providers who encourage immunization, pharmaceutical companies, and more. In the coming chapters, we will dispel the many myths about vaccines, but this chapter seeks to recognize and acknowledge the risks that do come with vaccinating. Contrary to what anti-vaccination supporters would assert, these risks are not being kept secret from patients to knowingly put them in harm’s way. Instead, they are readily available for people to read about, and they are typically much less common or worrisome than people opposed to vaccination would have us believe.
Most of you know this, but if there are any nonmedical people reading this book (and I hope that there are), I want to make it clear that no doctor or scientist has ever claimed that vaccines are 100% safe. As we read in chapter 5
, vaccines undergo rigorous testing and retesting, both before and after licensure, to discover any safety issues present. Many vaccines never make it to market because they either didn’t achieve their goals or their risks were too great. But when a vaccine proves to be effective and safe enough for widespread use, like any other medical intervention, it still has possible risks. The staunch anti-vaccine folks are likely to take those last two sentences and twist them to make it sound as if doctors are knowingly harming people. So, let’s put it into context (Figure 7.1)
The risk of major adverse reactions (anaphylaxis, Guillain-Barré syndrome [GBS], etc) happening as a result of vaccination is exceedingly small—1 to 2 persons in a million. This pales in comparison to the risks of the diseases themselves. Measles, for instance, results in hospitalization for 1 in 4; encephalitis with the possibility of permanent brain damage for 1 in 1000; and death for 1 to 2 in 1000 patients infected. Meningitis infection results in death for 10 to 15 out of 100 patients infected, even with proper treatment. And what about some of the other things we do every day without thinking about their
potential risks? Seat belts, if improperly fitted, have the potential to injure or kill people, but we don’t stop wearing seat belts.4
We know that the benefit of wearing a seat belt in the event of a car crash far outweighs the risks of the seat belt itself. Physicians recommend exercise to everyone to maintain overall health and to reduce the incidence of heart disease, stroke, diabetes, and other serious diseases; yet, every year people are seriously injured or die while exercising.5
Do we stop exercising because of what happens to those unfortunate few? No. We continue on because we know that the chance of serious injury is small compared with the greater benefit from getting regular exercise.
These risks of common and uncommon events give perspective on the risks of vaccines.3,10,11
Now, should we do our best to make sure that these potential risks are minimized? For instance, should we ensure that our children’s seat belts are fitted properly? Yes. Should we check with our physicians to make sure we are healthy enough to engage in a vigorous exercise program? Absolutely! Should we choose the proper people to receive live-attenuated vaccines so that we don’t give an illness to someone whose immune system is compromised? Of course! Should we avoid giving a vaccine to someone during a serious illness or high fever? Most certainly! The point is, everything we do—in life and in medicine—has risks, and we do take measures to reduce those risks. The potential upside to pursuing preventative health measures is so great that we still do them despite the very minimal potential downside. We should think of vaccination in much the same way—the benefits far outweigh the risks.
That being said, we don’t want to downplay the possible adverse effects of vaccination just like we wouldn’t want to minimize the possible risks of any other intervention we do in medicine. We would never think of skipping a risk/benefit discussion with our patients who are headed into surgery, for example. We need to have a similar informed consent discussion when it comes to immunizations. However, I would argue that just handing someone a Vaccine Information Statement (VIS) prior to immunizing may not be adequate. How often do we thoroughly read the paperwork that we are given at the doctor’s office? Providing the VIS is required and important, but providing verbal informed consent will likely be more meaningful. This doesn’t mean that you have to have a long and detailed discussion of every possible risk and side effect of vaccines. Even a short discussion of the most common side effects following vaccination can set expectations so that patients and parents aren’t surprised or unnecessarily frightened if they experience an adverse reaction.
I suspect two reasons for why many people believe that the flu shot can make them sick. The first is our failure to adequately express the limitations of the vaccine in the first 2 weeks after administration (that it takes 2 weeks for the vaccine to become fully effective). The second is our failure to
caution our patient’s about the common and normal symptoms of a person’s immune system kicking into gear after vaccination (aches, fatigue, headache, low-grade fever, etc), an omission that leads people to attribute these symptoms to the flu shot making them “sick.” Setting up appropriate expectations is key, and patients will have greater confidence that we are not trying to “pull one over on them” if we are up front about possible risks. So, what are
some common and not-so-common side effects or risks of vaccines? This chapter seeks to answer this question while giving a bit of perspective so that we can see these risks for what they are—mild or highly uncommon.
RISKS THAT ARE COMMON TO ALL VACCINES
There are some generalities that we can make regarding possible side effects of all vaccines. Some are obvious, and one would think barely need mention, but others may be less intuitive and require some explanation so that patients know what to expect.
1. Vaccines hurt. Everyone’s pain threshold is different, but we can generally say that receiving a vaccine will likely cause some mild discomfort, both at the time of injection and possibly for a few days following. However, we should help our patients and parents understand that they don’t have to be afraid of this discomfort. The pain from vaccination is minimal and temporary and, in the case of infants and toddlers, almost immediately forgotten, but the benefit of vaccination can last a lifetime.
2. Redness and swelling at the injection site are common. Some reactions are more robust than others, but any penetration of the skin and muscle by a needle with injection of a “foreign” substance will bring about an inflammatory reaction (an expected part of the immune response). Sometimes this results in modest soreness, and other times we get more notable redness, warmth, swelling, and pain at the injection site. These are temporary reactions that aren’t considered worrisome, although they can certainly be bothersome to patients. We can counsel use of ice and anti-inflammatory medications, if tolerated, to reduce symptoms.
3. Allergic reactions can happen. People can have allergic reactions to almost anything. We can use a new lotion and develop an allergic contact rash. Babies can eat a strawberry or a nut for the first time and develop hives. The same is true for vaccines. However, these events are relatively uncommon and typically mild. More serious allergic reactions (anaphylaxis, angioedema, recurrent vomiting, etc) are exceedingly uncommon. But if they do happen, the doctor’s office is the perfect place to be. For all vaccines, a life-threatening reaction to a dose of the vaccine or to any of its components is a contraindication to future immunization with that same vaccine.
4. We might feel “under the weather” after vaccination. When we give a vaccine, we are essentially triggering the immune system in a much milder and more controlled way than it would be triggered by exposure to the live virus or bacteria. How do we feel when we develop an infection? We likely have many days of fever, aches, and fatigue. When our immune system encounters a killed or weakened virus or bacterium in the form of a vaccine, it kicks into gear to start making antibodies, and this can give us a very mild and short-lived version of those same symptoms. This is not “sickness.” This is proof that our immune system is working! It is important that patients know that this is common, expected, and not worrisome.
Risks of Live-Attenuated or Weakened Vaccines
1. Live-attenuated vaccines can rarely trigger the illness against which they are meant to protect. As stated previously, live-attenuated or weakened virus vaccines should not be given to people who have a suppressed immune system (for example, patients with leukemia, patients on chemotherapy, patients without a spleen, or pregnant women). A healthy immune system is strong enough to handle the weakened form of a virus and will either keep us from getting sick at all or will help us to have only minimal symptoms. However, people without a fully functioning immune system could become ill from the viruses or bacteria present in live-attenuated vaccines. We screen patients prior to administering these immunizations to prevent this from happening, but rarely, mistakes are made or patients have an underlying immune dysfunction that has yet to be recognized.
In this section, we will delve into individual vaccines and discuss the adverse reactions of which physicians and other medical professionals providing immunizations should be aware (Table 7.1)
. I will include both the routinely administered, US-recommended vaccinations,1
and less commonly given travel vaccines,6
as some of us provide or recommend these in our clinics for patients traveling internationally.
Diphtheria vaccine only comes in combination with tetanus (Td) or tetanus and pertussis (DTaP or Tdap).
Specific incidence is not established, but pain, redness, and swelling (termed a local reaction) is noted to be common after injection with diphtheria toxoid. These are short-lived and typically do not require treatment. Development of a nodule or abscess at the injection site has also been reported but is not common.
TABLE 7.1 Rates of Adverse Reactions Occurring with Vaccination
RATE OF RISK
Redness, swelling, and pain at the injection site occur relatively commonly with all injectable vaccines.
Occasional (up to 1/10,000)
Fever, malaise, muscle aches, headache, nausea, abdominal pain, syncope, and dizziness occur less commonly with certain vaccines.
Uncommon (up to 1/100,000)
Intussusception, brachial neuritis, febrile seizures, idiopathic thrombocytopenic purpura, Arthus-type reactions, and allergic reactions (hives) are uncommon responses to certain vaccines.
Rare (1-2/1 million)
Life-threatening reactions, such as anaphylaxis, angioedema, and Guillain-Barré syndrome (GBS), are exceedingly rare occurrences.
No medical intervention is without risk, but, when it comes to vaccines, most are very mild. Other more serious risks do occur but are extremely rare. Risks vary depending on the vaccine. Rates shown here represent overall risk.
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