Myth-buster: Flu vaccine doesn't cause influenza

Awareness needed to raise immunization rates

Can you bust the biggest myth of influenza vaccination? Finding a way to may make the difference in your immunization rates.

The myth: Influenza vaccine can give you influenza. The fact: The vaccine is not a live virus.

"Injectable vaccine is made up of parts of the virus," says William Schaffner, MD, chair of the department of preventive medicine at Vanderbilt University in Nashville and vice chair of the National Foundation for Infectious Diseases. "It can't reconstitute itself and become a virus.

"That is the most persistent myth. It is particularly well embedded among nurses."

FluMist, the nasal spray vaccine, uses a weakened live virus that is cold-adapted so that it cannot replicate in the warmer region of the lungs. It also cannot lead to influenza illness, although it can cause side effects that include headache, sore throat, runny nose, and cough.

The National Foundation for Infectious Diseases conducted an opinion survey among the general public and found that 46% believed that they could get influenza from the influenza vaccine.

An e-mail survey of health care workers who did not receive the vaccine found similar concerns among those who believed "it will give me side effects or a 'cold.'" Nurses were less likely to receive the vaccine than physicians, and outpatient nurses had higher acceptance rates than inpatient nurses, Schaffner says.

People tend to assume any symptoms they have around the time of the vaccine came from the flu shot, he says. After all, they're receiving the vaccine just as respiratory viruses are beginning to circulate.

"You get your inoculation or nasal spray, and three days later you get a respiratory illness," he says. "People falsely attribute their cold to the influenza vaccine."

They also attribute random headaches, achiness, or sniffles to the vaccine. "The symptoms people say they get after the flu shot are the same ones they say they get after they didn't know it, but we gave them a placebo," says flu vaccine expert Greg Poland, MD, director of the Mayo Vaccine Research Group at the Mayo Medical School of the Mayo Clinic and Foundation in Rochester, MN. "Yet this [myth] persists."

To make matters more confusing, flu symptoms can be quite varied. Some people remain asymptomatic and others have only a sore throat, a low fever, a dry cough, and a runny nose for a few days. Yet the flu can cause a high fever; a persistent, hacking cough; extreme tiredness; headaches; and other respiratory symptoms with the potential complication of pneumonia. About 36,000 people die each year from complications of influenza.

So how can you combat this deep-seated myth? Provide information on the flu and flu vaccine — again and again. Repetition is the key, says Schaffner. "You have to keep telling the truth over and over again," he says.

Make sure health care workers understand the difference between the cold and the flu — and that the "stomach flu" isn't influenza at all. Nausea, vomiting, and diarrhea are rare influenza symptoms in adults. "The only thing the flu shot protects against is influenza, not the hundreds of other organisms that circulate in the winter," says Poland.

Present data about the effectiveness of the flu vaccine. If the vaccine is a good match with circulating strains, the effectiveness is about 70% to 90% among healthy adults, according to the Centers for Disease Control and Prevention. Even with a match that is not optimal, the effectiveness may be 50% to 60%. Vaccination also may reduce hospitalizations from complications of influenza.

Hospital leadership can play a key role by prominently promoting the flu vaccine, says Schaffner. Even if you think you've gotten the word out about the importance of the flu vaccine, keep up your awareness campaign. Myths die hard.

"One hopes, in due course, we will wear it down," says Schaffner. "I suspect we will never eliminate it completely, unfortunately."