Pregnant women should still get flu shots

A pregnant woman gets her flu shot at the Fairview clinic in New Brighton, Minnesota. It is important for pregnant women to continue getting their flu shots despite the findings of a single study.

A pregnant woman gets her flu shot at the Fairview clinic in New...

Many pregnant women probably feel nervous after recent headlines about flu shots. Researchers published a paper showing a small association between flu shots and miscarriages.

Notice the researchers never said flu shots increased the risk of miscarriage, and certainly not that the vaccinations caused such sad events. Doctors groups were quick to say pregnant women should continue getting flu shots for vital protection for the fetus and the mother.

How can both be true? Understanding the answer calls for a deeper explanation of how science works.

It is extremely rare for any single study to prove something is true. Medical advice is based on a body of evidence, with many studies involving thousands of patients whose findings all point in the same direction. That is what today’s vaccine recommendations are based on — a tremendous amount of research, with more ongoing, finding that vaccines are both safe and effective.

Opinion

This is why last year the CDC changed its recommendations so that children now get the flu shot instead of the nasal mist vaccine. Continued testing showed the mist no longer appeared effective. This comprehensive body of research on the nasal mist vaccine is a far cry from the single and, as it turned out, fraudulent study by Andrew Wakefield that claimed a link between the measles vaccine and autism. Look at the large body of evidence in this field, and you will see no link between autism and the measles vaccine.

We as consumers naturally tend to react to each new finding. That is why we often feel frustrated by what looks like ever-changing advice about diet and exercise (e.g., is butter in coffee now considered healthy?). Single studies make headlines that appear to tell us another way to live longer or better, but if those findings cannot be replicated in numerous other studies, they have questionable value as health guides.

Two years ago, 270 researchers took on the task of examining 100 studies published in prestigious journals of psychology, trying to replicate the findings in each. Their results? They reached the same conclusions in only 39 of the studies.

It is also worth noting that the study on miscarriages was correlational in nature. Researchers looked only at whether the number of miscarriages was higher in the sample of pregnant women who had gotten the flu shot. However, correlation is not the same as causality. Perhaps there was some other common factor among the women in this study. One thing we know is that they were older, which increases the risk of miscarriage. We call these untested elements “confounding factors.” A previous, much larger study found vaccinated women had about half the chance of miscarriage than unvaccinated women.

None of this means we should ignore the new study. Quite the opposite. We must conduct even more research, as the researchers themselves said, to further identify any confounding factors. Pregnant women and their doctors need a large collection of high-quality evidence.

A strong body of evidence tells us the influenza virus, not the flu shot, poses grave dangers to pregnant women and their fetuses. Flu is especially dangerous to newborn babies, who cannot be vaccinated for the first six months of life. They receive a few months of protection from the vaccine their mothers received during pregnancy.

Pregnant women should ask their OB/GYN about vaccine concerns they have. They also should know there is very strong evidence saying they should protect themselves and their babies through vaccination.

Allison Winnike is the president and CEO of The Immunization Partnership, a nonprofit vaccine advocacy and education organization serving Texas.