More than one million Americans are believed to have contracted the swine flu (H1N1) since it first emerged in March. Even though the new virus appears to be no more dangerous than the seasonal flu (which kills about 36,000 Americans a year), any new strain of influenza is a serious threat, particularly for patients at high risk for complications.
Americans will need two different influenza vaccines this year — one (likely to be given in a two-part series) for H1N1 and another for seasonal flu. To learn more about the benefits and risks of the vaccines, Bottom Line/Personal spoke with William Schaffner, MD, one of the country’s top specialists in influenza prevention…
When can I get the new vaccine?
We are predicting that the first shipments (about 45 million doses) will be ready by mid-October, with about 20 million additional doses prepared weekly after that.
This delay is unfortunate but not totally unexpected. Every year, there’s a race to prepare the vaccine for the normal seasonal flu. The vaccine for H1N1 has to undergo the same process.
The influenza virus is grown in eggs and is processed. All of this takes time. We’ve discovered that the H1N1 virus grows in eggs much more slowly than the viruses that cause seasonal flu. This means that it takes longer to prepare.
Will there be a vaccine shortage?
There may be shortages when the H1N1 vaccine first arrives in clinics, doctor’s offices and hospitals. It’s unlikely that shortages — if, in fact, they occur — will last very long. Manufacturers are expected to produce about 195 million doses, enough for two-thirds of the US population.
Will the vaccine be rationed at first?
This term isn’t used by public health experts. A Centers for Disease Control and Prevention (CDC) committee has recommended that certain higher-risk groups receive the H1N1 vaccine when it first becomes available.
For H1N1, those most at risk include pregnant women, young children (six months through four years of age) and patients with certain underlying health problems, including lung and heart disease. Health-care workers also will be first in line for the new vaccine because they need to stay healthy and on the job — and we cannot have them transmitting influenza to their patients.
In practical terms, anyone who wants the vaccine probably will be able to get it — if not immediately, then certainly within a few weeks after it’s available.
Why aren’t older people a priority for the vaccine?
Young people with swine flu tend to get sicker than older adults, the opposite of what happens with seasonal flu. People age 60 and older may have some immunity to the new virus from exposure to H1N1 viruses that circulated from 1918 to 1957. The immune systems of people in younger age groups are unprepared for this particular virus.
Can the new vaccine trigger Guillain-Barré syndrome as another swine flu vaccine seemed to do in 1976?
Some have speculated that the H1N1 vaccine might increase the risk for Guillain-Barré syndrome, a potentially dangerous autoimmune disease. This is highly unlikely. Out of more than 40 million people vaccinated against swine flu in a 1976 campaign, only a relative few — numbering in the hundreds — contracted Guillain-Barré. No evidence has convincingly linked Guillain-Barré to influenza vaccines since 1976.
So the new vaccine is safe?
We’ve studied the H1N1 vaccine — and additional studies are under way. We’re not expecting any safety problems at all.
What side effects can we expect from the vaccine?
Every vaccine, including the vaccine for seasonal flu, can cause minor side effects, such as bruising at the injection site.
Is it certain that the vaccine will work?
Yes. The H1N1 virus has remained very stable genetically, so an excellent match between the virus and the vaccine is anticipated.
Why is it likely to be given in two doses?
Because H1N1 is a new strain, patients likely will need two vaccine doses to fully prime the immune system. The doses would be given three to four weeks apart. Most people would achieve full immunity about 10 days after the second vaccination.
Do I need the vaccine if I’ve already had the swine flu?
People who have been exposed to either H1N1 or the seasonal flu will have immunity to that particular virus in the current year. In theory, they wouldn’t need to get a vaccination for the flu that they had.
However, the vast majority of patients who were diagnosed with H1N1 were not tested specifically for the virus. This means that they can’t be 100% certain that they actually had swine flu — and thus they should get the vaccination.
It’s normal for flu viruses to change from one year to the next. Even if this year you have H1N1 or you receive the vaccination, you still will need to be reimmunized in subsequent years.
Can I get the swine flu and seasonal flu vaccines at the same time?
Ideally, most people will already have received the seasonal flu vaccine by the time the H1N1 vaccine is available. For those who haven’t, it’s fine to get both at the same office visit. One inoculation could be given in each arm, or you could receive the swine flu vaccine by injection and the seasonal via nasal spray. It should be noted that the seasonal nasal-spray vaccine is an option only for healthy people ages two to 49 who are not pregnant.
