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Boost Your Flu IQ: Your Questions Answered

A 5-year-old boy receives the H1N1 flu nasal mist Wednesday in Rockville, Md.
Tim Sloan
AFP/Getty Images
A 5-year-old boy receives the H1N1 flu nasal mist Wednesday in Rockville, Md.

With the swine flu virus more widespread than ever and concerns about availability of the vaccine circulating, we solicited your questions about the pandemic. NPR's health editors, Joe Neel and Anne Gudenkauf, teamed up with Dr. Andrew Pekosz and Dr. William Schaffner to tackle your questions.

Pekosz is an expert on viruses and immunology and a professor at Johns Hopkins Bloomberg School of Public Health. Schaffner is an infectious disease expert and professor at Vanderbilt University.

In our coverage of the 2009 pandemic flu, we use the terms H1N1 and swine flu interchangeably. We also say pandemic flu. Since there are many H1N1 flu viruses, it would be confusing to only say H1N1. Swine flu is a scientifically accurate term because the virus has genetic material from a swine virus. The Centers for Disease Control and Prevention calls it 2009 H1N1 Flu (Swine Flu).


What is the efficacy of flu vaccines in general? I'm not clear, especially given the recent article published in The Atlantic? — Jennifer Meegan from Bozeman, Mont.

Influenza vaccines vary in their effectiveness, but overall they do their job quite well. Among young, healthy people, flu vaccines are 80 percent or more effective in preventing the strains of the disease contained in the vaccine.

Older people, and people who are in some way immunocompromised or have underlying illnesses such as heart disease or diabetes have a less effective immune response. For them, the vaccine may not prevent them from catching the flu, but it should keep the disease mild if they do catch it. So this group may still get a day or two of flu, but the vaccine helps to prevent complications like pneumonia, hospitalization and death.

But there is a key way the 2009 H1N1 vaccine is different from seasonal flu vaccines. For seasonal flu, experts make their best, educated guess about what flu strains will be dominant that year and make the vaccines to protect against those strains. So if they guessed the wrong strain, the vaccine doesn't offer protection. Also, there's a chance that multiple strains are circulating during flu season.

However, "the H1N1 vaccine is not only on target, but it's a bull's eye right in middle — this is a maximally effective influenza vaccine," Schaffner says, because the H1N1 flu virus has remained incredibly genetically stable since last spring.


My younger son (then 13) got the swine flu last spring. But what about my older son (16)? He shares his room with his brother, so was exposed to the germs. Should he be considered immune? — Neal Rauch from the Washington, D.C., area

Unless your son has had a laboratory-confirmed case of 2009 H1N1 — not just a confirmed case of influenza, or unless you believe that your son's flu-like symptoms were an infection with 2009 H1N1 — you should not assume that your son had swine flu or your other son was exposed to it. Getting vaccinated is the best way to ensure you are protected from influenza, so both your sons should get the vaccine, Pekosz says.

Exposure to the flu doesn't make you immune, Schaffner adds. And, there's no adverse affect in vaccinating someone who has already had swine flu.

My wife is pregnant and has been advised to avoid eating fish because of mercury found in seafood. Should she be getting a flu vaccination that has been made with a mercury-containing preservative (thimerosal)? — Chris from Seattle

"Thimerosal and vaccine safety has been investigated quite thoroughly, and there have been no associations between getting thimerosal-containing vaccines and any kind of adverse side effects," Pekosz says. The amount of mercury in a dose of thimerosal-containing influenza vaccine is well below the safety levels for mercury exposure and has been deemed safe by the American College of Obstetricians and Gynecologists and other experts.

If for personal reasons you still want to seek out a thimerosal-free vaccine, the nasal spray vaccine doesn't contain it, and some of the injectable vaccine is also made without it. But, Schaffner says, it may take longer to track down than the standard swine flu vaccine.

"Were it my wife, she'd be vaccinated as quickly as possible," Schaffner says, rather than leaving her susceptible to the virus for a longer time. Nationwide, more than 100 pregnant women already have been admitted to intensive care, and 28 have died.

Nicole Andreacchio, who is seven months pregnant, waits in line to receive the swine flu vaccine from the health department Thursday in  Maple Glen, Pa.
Matt Rourke
Nicole Andreacchio, who is seven months pregnant, waits in line to receive the swine flu vaccine from the health department Thursday in Maple Glen, Pa.

I am the parent of a 6-month-old and a 2-year-old; both are in day care. Are the kids more or less susceptible to the flu after the first shot, and before the second one takes effect? Can the seasonal and H1N1 shots be taken on the same day? — Tara Lund

Getting the first dose of the vaccine will provide some protection against disease, and it does not make you more susceptible to the flu. (Right now, kids require two doses of the H1N1 vaccine, with a four-week wait period between. The World Health Organization said Friday that even kids can get by with a single dose of swine flu vaccine. But the U.S. is sticking by the recommended two doses for now.)

There is no prescribed waiting period between seasonal and 2009 H1N1 injectable vaccines. There is no waiting period if you take a nasal spray vaccine for one strain and an injectable vaccine for the other. It's only if you want to take the nasal spray form of both seasonal and 2009 H1N1 that you should wait about three weeks between vaccinations.

I would like to know about the spread of H1N1 in the Southern Hemisphere between May 2009 and October 2009. How has the virus affected them during their winter? — Ben Johnson

The Southern Hemisphere, which is just now ending its winter, experienced a very active influenza season with increased numbers of cases and increased severe cases of influenza. The vast majority of cases of influenza — but not all — were from 2009 H1N1 infection.

Also, in the Southern Hemisphere, the virus is affecting the same populations as up in the northern half — kids and young adults. To date, the virus is behaving the same around the world; it has not mutated genetically or changed the way it spreads. Some countries have better provisions of medical care than others, which affects their ability to handle complications from the flu.

Are we going to be talking 10 years down the line about all of the hand sanitizer-resistant virus strains we now have to deal with? — Amelia Dickerson from Boulder, Colo.

Alcohol-based hand sanitizers work very well against influenza because they dissolve the virus' outer coat, making it non-infectious, Pekosz says. Resistance of influenza to alcohol-based sanitizers is not going to develop like it can in bacteria.

And, the H1N1 virus remains susceptible to the antivirals Tamiflu and Relenza. Patients with underlying conditions or any case where the illness seems to be getting more serious — persistent illness, getting better than worse, breathing problems, not being able to take fluids — should talk with his or her doctor about getting anti-viral treatment.

Around the world only 28 H1N1 viruses have been found that are resistant to Tamiflu and Relenza, but these are individual mutations that they haven't spread, so the circulating swine flu remains susceptible. "It's a remarkably genetically stable virus," Schaffner says. "We always see genetic variation in seasonal flu but in contrast this virus has remained stable."

We have found this flu no different than any other, in fact more mild. It seems like media coverage is just hype, promoting fear. Why is no one talking about preventative measures like diet, plenty of sleep and lots of fresh water? — Jess Jacobson

"I agree that keeping oneself healthy through exercise, getting plenty of rest and having good dietary habits is very important," Pekosz says. "However, 2009 H1N1 virus is infecting perfectly healthy people and sometimes causing very severe disease in them. Practicing good health habits will help you fight off the flu, but it won't guarantee that you won't be infected."

Many of you asked: Why won't doctors test everyone with flu symptoms to see whether they have pandemic H1N1?

If it's the flu, at least right now, it is swine flu because the pandemic H1N1 virus is practically the only flu bug in town. Epidemiologists, statisticians, and even your doctor don't need to test each and every patient to know that.

The government has a survey system in place — they get sophisticated test results on enough flu patients around the country to be able to say with authority what is happening nationally. That test is pretty expensive, so it's not available everywhere.

Your treatment doesn't depend much on knowing which variety of flu you might have. Physicians always want to monitor adults and children with the flu to make sure they don't become seriously ill, no matter what flu it is. And fever medications, fluids and bed rest are the best treatments whether you have swine flu or seasonal flu.

I am a 66-year-old diabetic male, and I have already had the seasonal flu shot. Should I also get the H1N1 shot since I am in the "susceptible" category (diabetic)? — Janak Varma

According to the CDC guidelines, you fall just outside the recommendations for a shot at this time. Later, you'll probably want to get one, even though this H1N1 virus is not attacking many older adults. The CDC's target groups for when vaccine is first available include:

pregnant women persons who live with or provide care for infants aged less than 6 months (e.g., parents, siblings, and daycare providers) health-care and emergency medical services personnel persons aged 6 months to 24 years persons aged 25 to 64 years who have medical conditions that put them at higher risk for influenza-related complications

The CDC says there are about 159 million people in these groups.

When vaccine becomes more widely available, it is recommended that people at higher risk for influenza-related complication — those are people with chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, neurologic/neuromuscular, hematologic, or metabolic disorders (including diabetes mellitus) and immunosuppression (including immunosuppression caused by medications or by HIV) conditions --- should get vaccinated.

With two children under 5 years old in my household, I was hoping for a thimerosol-free version of the H1N1 vaccine for them. Do you know if this will be available? — Jenifer Lienau from Aptos, Calif.

Yes, thimerosol-free doses are available. These come in single-dose vials, and the nasal flu mist vaccine is also thimerosol-free. Thimerosol, as you may know, is a preservative that keeps vaccine vials from becoming contaminated with bacteria. It's used in multiple-dose bottles (usually 10 doses per vial) to prevent any bacteria that might get in from growing. The single-use vials don't carry that risk.

It seems that most of the reporting we hear is very pro-flu shots, yet all shots carry risks, and this newest shot has barely been tested. Will you also cover the very real risks of getting a flu shot in your news coverage? — Erik Feder

We do weigh the risks vs. the benefits of any medical treatment or prevention technique in our coverage. You're right that a shot, or any medical intervention for that matter, carries a risk. For the new H1N1 flu shot, the risk is very low. Public health officials had a couple of options when deciding which flu shot to use for the new pandemic strain of H1N1. As we've reported, they decided to use the same method as used for the regular seasonal flu shot — which has a long track record of safety. You can read more about FDA approval of each of the 2009 H1N1 vaccines.

A nurse-physician assistant said that if I received the flu shot during the first swine flu outbreak in the 1970s that I should not need it now. — Pete Sokolosky from Cheyenne, Wyo.

The flu strain in the 1970s swine flu shot is not related to the current strain. So that vaccination offers no protection for the swine flu. The CDC recommends that everyone get the current H1N1 vaccine when it becomes available to the general public.

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