If results are too good to be true, you can't exclude harms

Confounded studies are unhelpful

I recently read this paper that appears in JAMA, and found it disappointing.

The purpose of the study was to ask whether mothers who received the COVID19 vaccine during pregnancy had increased risks of adverse events in their neonates around birth.

Rest assured, the study found

And that is how people interpret it on twitter

It turns out you cannot be confident of that at all. Here is why.

There are HUGE differences in neonatal death that cannot possibly be due to vaccination. Even the authors admit this

If that is the case, then the paper PROVES that the women who get the COVID shot during pregnancy are otherwise healthier or well off than those who do not. This is reflected in their BMIs which look to me like more normo-weight BMIs. It would be great if full data were provided.

Given then that the women getting the shot are not comparable to those who do not, the paper fails at the most basic level to exclude harmful safety signals. The entire paper should probably be placed in the trash can.

I can only conclude that people who interpret the study like this are either not good at reading studies or have a preconceived story they wish to tell.

There are some interesting things in it though. Looks like LOTS of women in Sweden and some in Norway NEVER GOT any COVID vaccination

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