Swine Flu: 11 Things You Need to Know

Federal officials are planning for an H1N1 swine-flu pandemic that could infect 30 to 50 percent of the population this flu season, with the first cases possibly beginning this month. A vaccine will be crucial for protecting people ... when it's ready. But will it be too late? Who should get the shot? And how safe and effective will it be?

Fortunately, the new H1N1 virus has been mild so far. Though it has infected a million Americans, only 556 deaths have been reported to date, versus 36,000 a year for the normal seasonal flu. But H1N1 also arrived very late in the last flu season and did not spread through the whole country. This year the vulnerable population will be much larger. The CDC produced a video last year called Why Flu Vaccination Matters. It features interviews with parents who have lost healthy children to the seasonal flu. Officials plan to update it this year with information on swine flu.

NEWSWEEK's Anne Underwood recently attended a two-day workshop on swine flu, including panels on vaccine preparedness and safety, at the Centers for Disease Control and Prevention. She answers important questions about the vaccine.

I'm a healthy adult. Do I need to be vaccinated?
Federal officials do not want to discourage anyone from getting the shot. But the CDC is only specifically recommending vaccinations for people at high risk for complications. "More than half the U.S. population is in these risks groups," says Dr. Anne Schuchat, director of CDC's National Center for Immunization and Respiratory Diseases (NCIRD). The groups are:

1) Health-care and emergency workers
2) Pregnant women
3) Children and young adults, from 6 months to 24 years of age
4) Parents and caretakers of babies under 6 months old (since infants under 6 months have a poor vaccine response, the best defense is having parents who are flu-free)
5) Adults ages 25 to 64 who have underlying medical conditions, including diabetes, asthma, and chronic lung disease or heart disease

So the answer to the question is generally no. As a healthy adult with no underlying conditions, you do not need a shot. But according to Schuchat, "Most adults don't think of themselves as having risk factors, even when they do. They feel fine, they go to work." If you have diabetes, consider getting a shot. If you have asthma, consider the shot.

When will the vaccine be available?
The government has ordered 195 million doses of vaccine, 45 million of which will be delivered by mid-October. But because most people lack prior immunity to the new H1N1 virus, officials expect that two injections will probably be necessary, spaced three weeks apart. Clinical trials are currently underway to confirm whether two shots are actually needed and to determine the optimal dose. Re-sults from those trials will be available in late September or early October. But even after receiving the vaccine, a person will take at least five weeks to develop full immunity. (Preliminary reports from some drugmakers suggest that there may be swine-flu vaccines that work with just a single shot, but it's unclear how that would af-fect the global vaccine supply; the World Health Organization has yet to review the data.)

So even if I get the shots right away, I won't have proper immunity until December. Isn't the swine-flu season supposed to peak in October?
Officials don't know how the swine flu will behave this year. "The only thing that's certain is uncertainty," says Dr. Thomas Frieden, director of the CDC. Officials suspect that the flu season will strike early this year because—in contrast to seasonal flu—H1N1 continued circulating in the United States during the summer. The fact that school is coming back into session will likely fuel the spread. But it's common for flu to continue infecting people through March or April.

Why are two shots thought to be necessary?
People born after 1957 have not been exposed to a similar virus. The first dose "primes" the immune system to respond, but it's the second shot that triggers the production of antibodies. This is not unusual. A number of vaccines are given for the first time in multidose series. For example, the seasonal flu vaccine is given in two shots to children under 9 if they've never had the flu.

If I receive the swine flu shot, do I need the regular flu shot, too?
Yes, if you're in the risk groups for both types of flu. That would mean a total of three shots—or four for a child under 9 who has not previously had the flu or been vaccinated for it.

Why does it take so long to produce a vaccine?
It is a multistep process, just as it is for seasonal influenza vaccine each year. However, the new H1N1 virus did not emerge until April in this country, so the process started later than usual. In May, scientists produced a recombinant version of the virus that would grow well in eggs. Vaccine manufacturers take that new virus and inject it into millions of eggs, where the virus replicates. When enough virus has formed, manufacturers harvest the virus, inactivate it, extract individual proteins from the viral coat, and combine those segments with other ingredients to produce a vaccine. (The process at this stage is slightly different for the nasal vaccine, which uses a live, if weakened, virus.) The vaccine then has to pass tests for potency and sterility. And clinical trials are needed to determine the optimal dose and number of shots that people will need. Trials for the H1N1 vaccine were announced in late July and should wind up around late September.

How effective is the vaccine?
It is expected to be very effective. The problem with normal flu vaccines is that influenza viruses are notorious "shape shifters," says Dr. Jay Butler, director of the CDC's H1N1 Vaccine Task Force. They mutate rapidly and can even exchange genes with other strains of flu. However, federal officials know from monitoring H1N1 in the Southern Hemisphere this summer that the virus has been unusually stable. Therefore the immune response generated by the vaccine should match the circulating strain of swine flu. "The vaccine will be effective," says Butler.

Is it safe?
In 1976 more than 500 people contracted an autoimmune disease called Guillain-Barré syndrome after receiving swine-flu shots in response to a small outbreak in Fort Dix, N.J. Some people understandably fear a repeat of that tragic episode. However, vaccine-production techniques have changed since then. Today, vaccines are highly purified to eliminate any potential contaminants. In addition, scientists use only selected viral proteins in the shots, not the entire virus, as they did in the 1970s. "The public is comparing this vaccine to the 1976 swine-flu vaccine," says CDC spokesperson Abbigail Tumpey. "In fact, the best comparison is to the seasonal vaccines of the last ten years."

I'm concerned about reports of autism caused by vaccines.
Sore arms and mild fevers are not unusual after receiving seasonal flu shots. "But the science is extremely reassuring" that vaccines do not cause autism, says Kris Sheedy, director of community outreach for NCIRD. Anyone who's concerned about the mercury-based preservative thimerosal (which is added to multidose vials of flu vaccine to prevent contamination) can request one of the thimerosal-free versions: the nasal vaccine or a single-dose preloaded syringe. The government anticipates having enough of these to meet the demand for young children and pregnant women. (There are some individuals who cannot receive the nasal version, including children under 24 months, children under 5 with asthma or recurrent wheezing, and asthmatics in general.)

This vaccine is egg-based. What if I'm allergic to eggs?
You should avoid the vaccine. If you're in a high-risk group and you come down with the flu, see your doctor immediately. Antiviral medications, given within 24 to 48 hours of the onset of symptoms, can dramatically improve one's outcome.

Until the vaccine is available, what should I do to protect myself?
It's most important is to wash your hands frequently and well—20 seconds with soap and water—and avoid touching your eyes and nose. Alcohol-based hand gels are also effective. Second, to avoid spreading germs, cover your mouth when you cough or sneeze, preferably using your sleeve or a tissue. And third, if you're sick or your child is sick, stay home until the fever has gone away for at least 24 hours without the use of fever-reducing medication.