Chapter 109
The Flu Shot
In the United States, more than 90 percent of children get the standard childhood vaccines such as polio and MMR, but most adults don’t get all their booster shots. Assuming someone has received all childhood vaccines (and vaccinations during a pandemic), health authorities recommend annual flu shots for adults, a tetanus booster every ten years (even though the WHO does not consider that necessary), a shingles vaccination at 50, and a pneumonia vaccination at 65. There are additional vaccinations for certain groups, for example hepatitis A for people experiencing homelessness, people with chronic liver disease, or men who have sex with men; or a hepatitis B vaccine series for healthcare workers and incarcerated people. Ask your doctor about an individualized schedule.
How safe are vaccines? In a systematic review with meta-analysis, the RAND Corporation examined more than 50,000 sources of evidence in 2021 and concluded that routine vaccinations can be considered safe and only rarely have severe side effects, such as severe allergic reactions in one to ten people per one million vaccinated. Temporary autoimmune diseases (Guillain-Barré syndrome and immune thrombocytopenia) occur in about one to three people per million people vaccinated against influenza, or 10 to 30 per million with the MMR vaccine.
The Flu Shot
Each year, between 4000 and 20,000 people in the United States die of influenza; for the 2017/18 flu season, however, the number of deaths was estimated at 80,000, making it one of the deadliest of the last 50 years. Most flu-related hospitalizations and 90 percent of deaths occur in those over 65. The influenza mortality rate from 75 onward is 50 times higher than in those under 65. Nevertheless, health authorities recommend an annual flu shot for everyone six months and older, if only to prevent infecting people who are particularly at risk. As mentioned, the cruel irony is that flu shots produce weaker protection in older people—who need the protection the most—because immunity wanes with age.
Depending on the season, the vaccine reduces flu risk by about 40 to 50 percent. So one can say with considerable certainty that flu risk in healthy, younger adults is lowered from about 2 percent per year to just under 1 percent. In older adults there is a similar relative risk reduction—from 6 to 2.4 percent—but because their risk is higher and the consequences are worse, the absolute benefit is greater here as well.
In the Northern Hemisphere, flu season can start as early as September and last until March. The problem with vaccinating too early is that immunity may wane before the season is over, especially in older people. Authorities recommend getting vaccinated by the end of October, but vaccination at any time during flu season is better than none.
Yes, the flu vaccine can cause Guillain-Barré syndrome, an attack by the immune system on the nervous system with weeks of paralysis, but influenza can as well. As noted, there are only one to three additional individual cases of Guillain-Barré per one million vaccinations compared with about 17 additional cases per one million cases of influenza. So it is much more likely to be temporarily paralyzed by influenza than by the flu shot; however, since about 30 older people have to be vaccinated to prevent one flu case, it must be assumed that vaccination nonetheless increases overall Guillain-Barré risk. The flu shot is not recommended in order to reduce the risk of a rare autoimmune syndrome, however, but to curb the common—and devastating—effects of influenza, which go far beyond a respiratory infection.
In the week after a confirmed bout of influenza, heart attack risk shoots up sixfold. The inflammation from the infection can destabilize atherosclerotic plaques, narrow arteries, and increase the danger of blood clots. So does the flu shot save lives in more ways than one? Those who get vaccinated against influenza actually have, on annual average, a lower risk of dying from cardiovascular disease or from all other health causes. Put another way: People who regularly get vaccinated against influenza live longer on average. But who gets vaccinated against influenza disproportionately often? White, married nonsmokers from higher social strata with higher educational levels, higher income, and health insurance. So only a study can determine whether this is cause and effect.
There have been four randomized controlled trials—flu vaccination versus placebo—in people with preexisting heart disease, and those who received the real vaccinations generally had a 56 percent lower risk of dying of cardiovascular disease and a 47 percent lower overall risk of death. The flu shot can therefore truly be an extraordinary lifesaver. It is still unclear whether the observational data showing fewer deaths overall—including among people without preexisting heart disease—will yield similar results.
Given the benefit, vaccine fatigue should be easy to overcome by correcting misinformation, but unfortunately debunking vaccine myths can also backfire. Refuting the myth that inactivated influenza vaccines (the ones administered to older people) can cause influenza surprisingly leads to even fewer people getting vaccinated. Refuting the lies that MMR vaccines cause autism or that the pertussis vaccine has massive side effects also paradoxically makes people less inclined to get vaccinated. Researchers concluded: “Correcting vaccine myths may not be an effective strategy for promoting vaccination.”
The Pneumonia Vaccination
“One might call pneumonia the friend of the aged,” wrote Sir William Osler, the “father of modern medicine,” in 1898. “Gently taken off after acute, short, seldom painful illness, the old man escapes those ‘cold gradations of decay’ that make him and his friends unhappy.” The idea was that pneumonia mercifully kills those who likely would have died soon anyway of a prolonged and painful illness. These days, the likelihood that healthy older people hospitalized with pneumonia will die in the following two years is not significantly higher than in younger adults in the same situation. But because of comorbidities in older age, pneumonia is the fourth leading cause of death worldwide and the ninth leading cause in the United States.
The most common cause of community-acquired (not in-hospital) pneumonia is pneumococci (Streptococcus pneumoniae). In addition to pneumonia, pneumococci can also cause middle ear infections, sinusitis, and conjunctivitis. It becomes serious when they enter the bloodstream, which can lead to meningitis (inflammation of the meninges), endocarditis (inflammation of the inner lining of the heart), or sepsis (a life-threatening organ dysfunction due to blood poisoning).
Thank God there are vaccines against pneumococci. The first was developed more than 100 years ago but fell out of favor when penicillin was discovered and people believed antibiotics would eliminate the danger. Unfortunately, these days up to 40 percent of pneumococcal infections are resistant to at least one antibiotic, and despite our miracle drugs, the mortality rate from invasive pneumococcal disease in older people is around 15 to 30 percent. According to randomized controlled trials, pneumococcal vaccinations can reduce the risk of pneumococcal pneumonia in those over 65 by 64 percent and, more importantly, reduce the risk of invasive pneumococcal disease by 73 percent. As with the flu shot, population studies found that pneumonia vaccination lowers the risk of heart attacks and also overall mortality risk, but unlike with the flu shot, there are no randomized controlled trials confirming this additional benefit.
The Shingles Vaccination
The shingles vaccine is not more widespread because there is a lack of awareness of this disease. Shingles occurs when the chickenpox virus is reactivated later in life. Once the body has overcome chickenpox, the virus hides in the spinal cord and lies in wait for an opportunity to strike again. When the body’s defenses are weakened, the virus can break out and wind forward along a nerve branching off from the spinal cord around one side of the body, forming skin blisters in a characteristic belt-like pattern that does not cross the body’s midline. (The name of the virus, zoster, comes from Greek and means “belt.”)