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There are ill-informed but also rational reasons for avoiding flu shots. The vaccine doesn't actually contain thimerosal, the preservative that used to be included in some other kinds of vaccines that is about 50 percent mercury. Flu shots don't weaken your immune system. The reality is, it's your immune system that determines your immunity to the flu after you take them.
However, influenza injections don't necessarily protect against the flu, either. They aren't usually formulated to protect against every possible strain of the virus that might be going around. Even when they are, they work about half to two-thirds of the time. You can get a flu shot for the right strain of flu and still come down with it. The hope is that enough people get vaccinated so enough people are immune so most people are never exposed to the virus.
One group of people we almost never consider, however, benefits from influenza vaccinations. That group is the unborn.
How Big a Difference Does a Flu Shot Make to an Unborn Child?
Mothers often rationalize that they should skip their annual flu shot when they know they are pregnant, but the data show that flu shots actually save fetal life. A recent study in Australia found that 51 percent fewer babies were stillborn when their mothers were vaccinated against the flu.
Researcher Annette Regan, MPH, of the Western Australia Department of Health, and her colleagues analyzed records of 58,808 women who had been pregnant during 2012 and 2013. They found that mothers who received an influenza immunization during any trimester of pregnancy had only half the rate of stillbirths. The rate of stillbirths was even more reduced among women who delivered their children just after the end of flu season. These women had a two-thirds reduction in stillbirths. And among women who had received a flu in the last two weeks of their pregnancy, there were no stillbirths.
Wrote Ms. Regan:
""There are more than 3 million stillborn infants each year worldwide, and in developed countries stillbirth accounts for 70% of perinatal deaths; confirmation of these findings would indicate that seasonal influenza vaccination in pregnancy has substantial perinatal health benefits.'"
Why Would a Flu Shot Protect the Unborn?
We don't usually think of unborn babies catching flu. After all, they don't need to breathe, they can't sneeze, and they certainly aren't going to complain (although sometimes a mother will just know) that they are sick.
On the other hand, it's well known that pregnant women are especially susceptible to complications of the flu such as acute respiratory distress syndrome and pneumonia. Many women brave these risks because they are afraid that taking the shot might harm their child. However, it appears that unlike other viral infections that devastating to the embryo, influenza is potentially deadly to the nearly fully formed fetus. Even if the mother has few or no symptoms, the fetus can suffer a severe infection and even die in the womb. The closer the baby is to term, the more likely death is from influenza infection.