The H1N1 swine flu virus appeared in the U.S. in April 2009 and never went away. After sweeping the globe, U.S. H1N1 swine flu cases surged as schools opened in the fall. What is H1N1 swine flu? What can we do about it? WebMD answers your questions.
What is swine flu?
What are swine flu symptoms?
Who is at highest risk of H1N1 swine flu?
Help! I've been exposed to swine flu. What should I do?
If I think I have swine flu,...
Isn't the 2009 H1N1 swine flu vaccine too new to trust?
Why should I believe what government scientists say about swine
Does the H1N1 swine flu vaccine contain thimerosal?
The 1976 swine flu vaccine wasn't safe. Why should I trust this
Do we really know what drugmakers are putting in the swine flu
Is the 2009 H1N1 swine flu vaccine safe?
No vaccine is 100% safe for everyone. People with allergies to eggs, for example, can't take flu vaccines
because eggs are involved in the manufacturing process.
And flu vaccines cause mild but common reactions. About one in three people
get a sore arm from the shot, some with a little redness or even swelling. Some
10% to 15% of people feel tired or get a headache; some may even run a low fever.
And vaccines can trigger rare but serious reactions, even among people with
no apparent allergies or sensitivities.
So if vaccines aren't 100% safe, why risk them?
Approved vaccines -- including the 2009 H1N1 swine flu vaccine -- are
calculated to be much, much less risky than the diseases they prevent. For
example, out of every million people who get a flu shot, one or two will get a
serious neurological reaction called Guillain-Barre syndrome (GBS).
But flu itself causes serious problems, including GBS, in far more than two
in a million cases. And since a large proportion of the population will get
swine flu, the vaccine risk is far smaller than the disease risk.
In clinical trials, 10,000 to 15,000 children and adults have received
various manufacturers' brands of H1N1 swine flu vaccine. Nothing serious
happened to any of them, including this reporter, who received a double dose of
the Sanofi-Pasteur swine flu vaccine.
That's still not proof that no harm will come from the vaccine. Clinical
trials cannot detect something bad that happens to one or two out of every
100,000 people vaccinated.
"There could be unknown side effects. Something could happen. But we think
that is highly unlikely," says infectious disease and vaccine expert Mark
Mulligan, MD, executive director of the Hope Clinic of the Emory Vaccine Center
"The CDC, FDA, HHS [Health and Human Services Department], the Department of
Defense, and several large HMOs with great medical records are all
collaborating in enhanced surveillance for this national 2009 H1N1 vaccine
campaign," Mulligan tells WebMD. "If there is a signal for a rare or late
adverse event, we will identify it as early and as quickly as we can."