Flu Shots: Facts and Fallacies

Vaccination is one of science’s greatest accomplishments; vaccines have prevented millions of deaths and eliminated smallpox forever. But rejection of vaccination is as old as vaccination itself. Some objections to it needn’t be taken seriously, like the argument that illness and death are part of God’s plan and humans mustn’t try to thwart His will. Or the chiropractor who told me “germs don’t cause disease.” However, some objections to specific vaccines require serious scrutiny: those that are based on an interpretation of the evidence that differs from the interpretation of the experts who write the immunization guidelines.

Of all vaccines, flu shots have come in for the most criticism. There are valid reasons to be skeptical. They are the least effective of all our vaccines. The influenza virus is constantly changing, and there is a lot of guesswork involved in choosing which strains to use in each year’s vaccine. And some of the studies on which the recommendations are based are flawed.

One of the flu vaccine’s most outspoken critics is Tom Jefferson, head of the Vaccine Field Group at the Cochrane Database Collaboration. He says “Flu researchers have been fooled into thinking vaccine is more effective than the data suggest.” He is absolutely right about that. But he goes too far when he characterizes all the published research as “rubbish.” Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, is more circumspect. He says, “I have no doubt that it is effective in conferring some degree of protection. To say otherwise is a minority view.”

Flu vaccine research is problematic. As many as half of people who have “flu-like” illnesses don’t actually have influenza; there are more than 200 other pathogens that can cause the same symptoms. The risk of influenza varies from year to year according to the virulence of the circulating strains. There is often a mismatch between the circulating strains and the strains in the vaccines. Many studies have measured antibody levels rather than actual decreases in the number of cases of influenza. Measuring deaths from flu can be misleading because flu can kill indirectly by making people more susceptible to complications such as pneumonia. If they hadn’t had influenza, they wouldn’t have died of pneumonia. Jefferson says “When an old person dies of respiratory failure after an influenzalike illness, they nearly always get coded as influenza.” Of course that’s not accurate unless the diagnosis of influenza was laboratory-confirmed. By the same token, however, some deaths coded as heart attacks or pneumonia may have been due to influenza.

The benefit to the population depends on individuals getting the vaccine. They may not benefit personally, but they indirectly benefit others by reducing transmission rates in the community and increasing herd immunity.

Jefferson calls for placebo-controlled trials, which most experts reject as unethical. The FDA required placebo-controlled trials before the flu vaccine first went on the market; those studies established that it is protective, and it wouldn’t be ethical to deny that protection to a placebo control group.

The claim that flu vaccine reduces death rates by 50% is almost certainly wrong. But there is compelling evidence that flu vaccines work. In studies where vaccinated subjects were deliberately infected with influenza virus that matched the strains in the vaccine, the protection rate was 96%.

The Science-Based Medicine blog’s Mark Crislip, an infectious disease specialist, reviewed the same published evidence that Jefferson had, and he emphatically disagrees with him. Even if Jefferson is right that the flu vaccine doesn’t reduce all-cause mortality, there is compelling evidence that it reduces the infection rate and the flu-related mortality of populations. The benefit to the population depends on individuals getting the vaccine. They may not benefit personally, but they indirectly benefit others by reducing transmission rates in the community and increasing herd immunity.

Certain people are particularly vulnerable and more likely to die if they get the flu: infants too young to be vaccinated, the immune-compromised (whether from disease or from immune- suppressing medications), pregnant women, and the elderly. The elderly are not as well protected by the vaccine because they don’t develop as high a level of antibodies as younger people. Fortunately a higher dose flu vaccine is now available with four times as much antigen. It is recommended for those over 65, and has been shown to decrease the incidence of flu in that population.

Crislip concludes, “The flu vaccine is of benefit. And the more people who get the vaccine, the greater the benefit for everyone.” As we like to say, “Don’t get the flu vaccine for yourself, get it for Grandma.”

Here are some of the many fallacious reasons people refuse to get their flu shots:

  1. It contains a neurotoxin, mercury, in the form of thimerosal. (Only the multidose vials contain thimerosal, you can request the single-dose version; and anyway thimerosal doesn’t cause autism and the World Health Organization says it’s safe.)
  2. I don’t need the vaccine because I’ve never had the flu. (Yet. There is no guarantee that you won’t get it. I’ve never had a house fire, but that’s not a reason to drop my fire insurance.)
  3. The vaccine gave me the flu. (Impossible. The injectable vaccine contains no live virus, and the nasal spray vaccine contains an attenuated form of virus too weak to cause the disease.)
  4. It doesn’t work: I was vaccinated but I got the flu anyway. (You may have had another flu-like illness or flu from a strain not covered by the vaccine. And if you got the flu from a strain that was covered, you probably had a much milder case than you would have without the vaccine.)
  5. It causes dangerous side effects. (Most side effects are mild and transient. Serious side effects are extremely rare. The disease is far more dangerous than the vaccine. A sore arm for a couple of days is a small price to pay for avoiding a disease that could kill you.)
  6. I can protect myself naturally with Echinacea, Airborne, vitamin D, and other natural preventive measures. (Dream on!)
  7. The flu isn’t so bad. (Yes it is! It can kill people, put them in the hospital, and cause symptoms so bad they wish they would die.)
  8. It hasn’t been evaluated for safety. (It was evaluated for safety before it went on the market, and surveillance is ongoing. There are 1342 references on PubMed on the safety of flu vaccine.)
  9. I don’t want to spend the money. (A funeral or a hospital stay costs a lot more than a flu shot.)
  10. “Injecting organisms into your body to provoke immunity is contrary to nature,” according to the infamous Dr. Mercola. (Nature kills people. Medicine is all about trying to keep nature from hurting people. “Contrary to nature” is a good thing.)
  11. I heard the vaccine causes narcolepsy. (In 2009 there were reports of an association between narcolepsy and one specific brand, Pandemrix, but only in a few countries and not in others. Correlation is not causation and it is still not certain whether the vaccine was responsible. No other brand has been linked to narcolepsy, and Pandemrix was never licensed for use in the US.)
  12. Fewer than 100 children die each year from the flu. (Preventing death is not the only reason to vaccinate. Children have the greatest rate of infection with the flu; 10–40% of all children are infected each year, and 1% of those are hospitalized. Children are the primary source from which influenza spreads through the population. And even one preventable death of a child is a tragedy.)
  13. There’s formaldehyde in the vaccine. (It’s used in manufacturing, but if there’s any left in the final product, it’s too little to measure. The body already contains a million times more formaldehyde from natural metabolic processes than the highest estimate of what might be in the vaccine.)

When healthcare workers are vaccinated, patient mortality declines. Some employers require healthcare workers to get the flu shot. This mandate has created a lot of controversy. One doctor said “Even if it were true that healthcare workers were transmitting flu to patients and that vaccination could prevent this from happening, forcing a professional to do even that which is beneficial is profoundly immoral.” But no one is being forced. A healthcare worker always has the right to refuse vaccination and take whatever consequences the employer imposes. The hospital has a duty to protect its vulnerable patients by not exposing them to unvaccinated staff. Those who argue for “health freedom” want the freedom to act foolishly and irresponsibly.

I once had a long e-mail debate with a man who refused to get the flu shot. He gave me his reasons one by one and I showed him evidence that refuted each of them. He finally agreed that I was probably right but said he still wasn’t going to get the shot because he’s afraid of needles!

I’ve been getting an annual flu shot for several decades now. I’ve never had the flu; but I’ve seen the harm it can do, and I want to keep taking every possible precaution to reduce my chances of getting it. And I want to protect others in my community.

Influenza kills around 36,000 people annually in the U.S. If even a few of those deaths can be prevented, isn’t the vaccine worthwhile? If even a few people can be spared the suffering of a nonfatal influenza attack, isn’t it worthwhile? If it will help protect the very young, the elderly, and the immunecompromised, shouldn’t the rest of us be altruistic enough to get the vaccine for their sake?

This article was originally published as a SkepDoc column in Skeptic magazine.

Dr. Hall is a contributing editor to both Skeptic magazine and the Skeptical Inquirer. She is a weekly contributor to the Science-Based Medicine blog and is one of its editors. She has also contributed to Quackwatch and to a number of other respected journals and publications. She is the author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon and co-author of the textbook, Consumer Health: A Guide to Intelligent Decisions.