5 myths about the flu

Updated 25m ago
By Liz Szabo, USA TODAY

In a new survey by Consumer Reports, only 30% of respondents were "very confident" that this year's flu shot is safe.

That leaves many doctors and scientists perplexed. Of all the many things to fear in the world, they say, vaccines should be at the bottom of the list. USA TODAY's Liz Szabo talked to vaccine safety experts to address some of the most common myths.


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Myth 1: The flu shot causes the flu.

The viruses in the flu shot are dead, so they can't give people the flu, according to the Centers for Disease Control and Prevention. Its most common side effect is soreness in the arm.

FluMist nasal spray contains weakened viruses, so they don't cause severe, flu-like symptoms, either. Side effects in children can include a runny nose, wheezing and headache.

So why do some people swear that they got sick right after getting a flu shot? Flu shots tend to be given at a time of year when respiratory viruses are beginning to circulate, doctors say. So it's only natural that some people will catch a respiratory bug shortly after getting a vaccine. And since it takes about two weeks after getting a vaccine for the body to develop immunity, some of those bugs could be the flu. But the vaccine itself isn't causing disease.

Myth 2: The flu is just a bad cold.

While some people develop worse symptoms than others, flu symptoms tend to be much more severe than — and come on much more suddenly — than a cold. Many who got H1N1 (swine flu) last year were out of work or school for a week with fever, body aches, sore throat, fatigue, headaches and a runny or congested nose, according to the CDC.

And unlike a cold, which generally goes away on its own after five days or so, the flu can cause life-threatening complications, mostly by causing secondary bacterial infections such as pneumonia.

The flu sends 200,000 people to the hospital and kills 30,000 in a typical year, the CDC says.

California obstetrician-gynecologist Jennifer Gunter says her 7-year-old son, Oliver, who was born prematurely, has been hospitalized for the flu twice. Both times, he came home from the hospital with an oxygen machine. Gunter caught H1N1 last year, before the vaccine was available.

"It was horrible," Gunter says. "I was off work for six days until I was no longer infectious."

In developed countries, influenza kills more people than any other vaccine-preventable disease, says pediatrician Jon Abramson of Wake Forest University School of Medicine and Families Fighting Flu, a non-profit health group.

Myth 3: This year's shot — which protects against both H1N1 and seasonal flu vaccines — is riskier than earlier versions.

Actually, the new flu shot was made the same way as every other flu shot, says Randy Bergen of Kaiser Permanente in Walnut Creek, Calif.

Every year, vaccine makers include circulating viral strains that are most likely to cause illness. Typically, these include two influenza A strains — an H1N1 and an H3N2 — and a strain of influenza B, Abramson says.

This year, manufacturers included the H1N1 strain that caused pandemic last year, Abramson says.

All drugs, including "natural" supplements and vitamins, have side effects. But the safety of vaccines is actually tracked more closely than just about any other drug. Unlike most medicines, "we have more hard facts when it comes to the flu shot," Gunter says.

Through the National Adverse Event Reporting System, investigators check out every serious side effect that people experience after getting a flu shot. Most aren't related to the flu vaccine. In fact, there were no deaths attributed to the H1N1 vaccine last year, Gunter says.

Myth 4: Only sick people need a flu shot.

While older people and newborns are usually at greatest risk for complications, swine flu is actually most threatening to the young.

Typically, about 90% of flu deaths are in people over 65. Last year, however, about 90% of flu deaths were in people under 30. About 10% of flu deaths last year were in children, according to the CDC.

When healthy people get vaccinated, it can help protect the weak, including cancer patients, anyone with a compromised immune system and newborns too young to get the shot, says Paul Offit, chief of infectious disease at Children's Hospital of Philadelphia.

Because babies can't be vaccinated until they're 6 months old, they depend on those around them — parents, grandparents, siblings, babysitters, hospital employees — to get the flu shot, creating a "cocoon" of protection, Bergen says.

Myth 5: Flu shots contain methyl mercury and other toxic chemicals.

Although there's no evidence that the ethyl mercury-based preservative thimerosal causes harm, vaccine makers responded to public concerns in 2001 and stopped using it in most vaccines.

Neither flu shots in individual-dose containers or the FluMist nasal spray contain thimerosal. Flu vaccine kept in multi-dose vials do use thimerosal as a preservative, to prevent the growth of fungus or other potentially dangerous germs, Bergen says. Patients can ask for the thimerosal-free versions.

But scientists note that all mercury is not the same.

Thimerosal contains ethyl mercury, which has not been shown to cause harm, rather than methyl mercury, the type that can cause brain damage, Offit says. While most laypeople don't pay attention to such differences, they're important. Consider the huge difference between ethyl alcohol — or drinking alcohol, found in wine and beer — and methyl alcohol, or wood alcohol, which can cause blindness.

There's also no data to prove that thimerosal causes autism, Offit says. In fact, seven studies now refute that idea.

Gunter notes that flu shots don't use aluminum, which is used in other vaccines as an "adjuvant" to stimulate a stronger immune response.

While many medications and consumer products have trace levels of chemicals, so do our bodies, Offit says. Breast milk has more mercury contamination than vaccines. So does infant formula. But vaccines, like breast milk, play a vital role in keeping infants healthy.

"If you have zero tolerance for mercury, you have to move to another planet," Offit says. "We all have mercury and formaldehyde and aluminum in our bodies. Vaccines don't add to what we normally encounter every day."

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