Op Ed: Flu shots protect both mother and unborn baby
Originally published in the Statesman
Many pregnant women probably feel nervous after recent headlines about influenza shots. Researchers published a paper showing a small association between flu shots and miscarriages.
Notice that the researchers never said flu shots increased the risk of miscarriage, and certainly not that the vaccinations caused such sad events. In fact, doctors’ groups were quick to say pregnant women should continue getting their flu shots, which provide 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.
For one thing, it is extremely rare for any single study to prove that 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 going on all the time, finding time after time that vaccines are both safe and effective.
This comprehensive body of research on the nasal mist vaccine is a far cry from a single and, as it turned out, fraudulent study by Andrew Wakefield claiming a link between the measles vaccine and autism. Look at the large body of evidence in this field, and you will see there is no link between autism and the measles vaccine.
We as consumers naturally tend to react to each new finding that shows up in headlines. That is why we often feel frustrated by what looks like ever-changing advice about how we should eat 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 guides to our health.
Two years ago, a team of 270 researchers took on the tremendous task of examining 100 studies published in prestigious journals of psychology, trying to replicate the findings in each. Their results? They were able to reach the same conclusions in only 39 of the studies.
It is also worth keeping in mind the study on miscarriages was not in correlation with nature. In other words, 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 group of 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 that vaccinated women had about half the chance of miscarriage than unvaccinated women.
None of this means that 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 on the topic.
Right now, a strong body of evidence tells us that 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 obstetrician about any vaccine concerns they have. They also should know that right now there is very strong evidence saying that they should protect themselves and their babies through vaccination.