As the influenza season heads in, Carol Baker, who chairs the National Foundation for Infectious Diseases' Childhood Influenza Immunization Coalition, answers some common questions about the flu vaccine. Baker is a professor of pediatrics, molecular virology and microbiology at Baylor College of Medicine in Houston.
Q. What is the flu vaccine and who should receive it?
A. The influenza vaccine protects against three different strains of the virus that are determined each year by flu trends in the Southern Hemisphere six months previously. This year's vaccine is identical to last year's. But even if you got the flu shot last year, it's still important to get one this year because the vaccine doesn't last more than a year, at most.
In general, everyone 6 months of age and older should receive the vaccine. It's especially important that the very old, the very young, people with compromised immune systems and pregnant women be vaccinated, because they are the populations more likely to develop serious complications. During the H1N1 flu pandemic in 2009, 5 percent of the deaths from the outbreak were pregnant women. Immunity passes from the mother to the baby in utero and protects them against the flu until they are old enough to be vaccinated. Because infants can't be immunized until they are 6 months, they should be surrounded by vaccinated people, just as cancer patients and other especially vulnerable people should be surrounded by people who are vaccinated.
Q. How effective is the flu vaccine?
A. Unfortunately, getting vaccinated won't guarantee you won't get the flu, but it greatly lessens the chance. Even if the vaccine is a good match to the flu strains that year, its effectiveness is just 70 percent. Everyone in the medical world agrees we need a better vaccine that covers all strains and lasts a lot longer. Scientists around the world are working on developing a universal vaccine that potentially would work like the measles vaccine — two doses and you're protected for life — but this is five to seven years off or longer.
Q. What is new this year?
A. The Fluzone high-dose vaccine, which is four times stronger than the standard dose, is being offered to adults 65 and older. The standard vaccine does not work as well in older people and young children, and we hope that the higher dose of antigen in this vaccine will strengthen their immune response.
For people who avoid the flu vaccine because they are afraid of needles, the intradermal vaccine uses an ultrafine needle to inject the flu vaccine directly into the skin, instead of the muscle. The needle is 90 percent smaller. Only healthy people, aged 18 to 54, can receive the intradermal vaccine.
This year, children under 9 who were fully vaccinated last year only need one dose of the flu vaccine, because it is the same as last year. Normally, children under 9 receive two doses. Children who were not vaccinated last year should receive two doses, as usual. Also, the American Academy of Pediatrics recommends that children with minor allergies to eggs receive the vaccine. Previously, children with egg allergies were not vaccinated. Parents of children with more serious egg allergies should talk to their health care professionals.
Q. What are some of the myths about the flu vaccine?
A. The oldest and worst myth I've heard — and I've even heard nurses say this — is, "I got the vaccine and it caused the flu." The shot is made up of dead virus that can't give anyone the flu, and even the live virus present in the nasal spray flu vaccine has been weakened so much that it won't cause any symptoms. It takes two weeks for the flu shot to become effective. That's why I tell people to get flu vaccine early. The flu usually starts with winter and peaks in February. If the vaccine is available in September, get it in September.
I also hear a lot of people say: "My child is healthy, so he doesn't need to be vaccinated. Only children with weakened immune symptoms really need the flu shot." In reality, about 150 children died last year from the flu, and about half of them were previously healthy. Likewise, about 20,000 children were hospitalized due to complications from the flu and about half of them were previously healthy.
Q. What can you do if you get the flu?
A. Remember, it's very contagious, so use cough and hand hygiene to keep it from spreading. Prescription drugs, like Tamiflu, are effective in shortening the duration of the illness, but you need to begin taking them within 36 hours of the onset of symptoms. People really shouldn't go to work. They're not productive and can make everyone else sick. The best thing, though, is to try to prevent the flu by making it a habit to get vaccinated every year.