We recently discussed the five most common misconceptions about flu vaccines, and answered questions about who should get the vaccine. Today we answer some common questions about the safety of the vaccine. We’re going to continue to answer your questions, so keep them coming in the comments.0
Q: Isn’t the swine flu vaccine untested and being rushed into use?
A: No. Here at Consumer Reports, we’re often skeptical about new drugs and treatments since they don’t yet have a long track record to establish their safety and effectiveness. But the 2009 H1N1 vaccine isn’t really a new drug, any more than the regular (seasonal) flu vaccine is. That vaccine is made from scratch each year using the strains of influenza virus most likely to circulate in the coming season, and decades of evidence show that it’s quite safe and moderately effective (some years are better than others) at preventing cases of the flu. The H1N1 vaccine is just like the regular vaccine, except it contains the new virus that causes the swine flu. Several clinical trials have shown the vaccine’s effectiveness at preventing H1N1 infection, and they revealed no significant safety problems, according to researchers. Those studies weren’t big enough to rule out rare adverse effects, which usually don’t emerge until a drug or vaccine has hit the market and been used by a large number of people. But there’s no reason to suspect that the swine flu vaccine is any more likely to produce such events than the seasonal flu vaccine. Health officials have put monitoring systems into place that are designed to catch any rare side effects that occur once the vaccine becomes available.
Q: I heard the swine flu vaccine has an untested ingredient called squalene. Is that true?
A: It is not true. None of the H1N1 vaccines approved for use in the U.S. contain that ingredient, which is used in some other countries in what’s called an adjuvant—a substance added to a vaccine to induce a greater immune response. In fact, the Food and Drug Administration has never approved any influenza vaccine that contains adjuvants. It’s true that the government is studying the safety and efficacy of adjuvants, but according to the CDC there are currently no plans to recommend developing an H1N1 vaccine that contains one. That could potentially change at some point—for example, if the virus mutated and an adjuvant helped provide better protection, or a vaccine shortage occurred and an adjuvant allowed limited supplies to stretch further—but it is not the case now.
Q: I’ve heard that the swine flu vaccine can cause Guillain-Barré syndrome. Is that true?
A: It’s very unlikely, though the risk can’t be completely ruled out. A swine flu vaccine developed in 1976 was associated with a heightened, though still rare, risk of developing Guillain-Barré syndrome (GBS), a serious neurological disorder. An additional case of GBS occurred in one out of every 100,000 people who were vaccinated against the 1976 swine flu. In comparison, only one in about every million people vaccinated against the typical seasonal flu develop GBS—and some studies have found no increase in GBS cases after seasonal flu vaccination at all. Researchers aren’t sure why the 1976 swine flu vaccine appeared to pose a greater risk of GBS, but health officials don't expect the same to happen with this year's vaccine. Moreover, the vaccine's protection against illness and complications from the flu, including pneumonia, hospitalization, and death, far outweigh the risks for most people, especially those in the priority groups for vaccination. What’s more, people are four to seven times more likely to develop GBS after having the flu itself than after the vaccine.
Q: Should I have the swine flu (H1N1) vaccine if I’ve had Guillain-Barré syndrome?
A: That depends in part on your risk of getting swine flu and becoming seriously ill if you do. GBS may be more likely to develop in people who have already had this serious neurological disorder. But the flu itself can also cause GBS, as well as complications such as pneumonia. If you’re among the priority groups for vaccination—including pregnant women, health-care workers, and people ages 25 to 64 with underlying health conditions—the shot’s benefits probably outweigh its risks. If you’ve had GBS within six weeks of getting vaccinated, avoid the H1N1 nasal spray, which has a weakened live virus, and discuss with your doctor whether to get the shot.
--Kevin McCarthy, associate editor
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