Will you consider updating your piece on pregnancy and COVID vaccination (or writing a new one) as more data and research become available? The piece I read was from December, and I am curious about how much has changed in recent months based on new research and data.

In some ways, not much! In others, we do know a bit more. Let’s run it down.

First, trials in pregnant women are underway now. Which is good! You can see some details here about Pfizer. These will follow pregnant women for 7 to 10 months after vaccinating them between 24 and 36 weeks of pregnancy. This is helpful in a sense, but obviously the results are very long term.

(Before you flood with questions about kid vaccines: Pfizer will also be testing in kids 5 to 12 soon, and under 5 later this year. Johnson and Johnson has already said they will start testing in infants. Kids 12-15 are underway already. So we have a plan on kids, also, but similarly not immediate.)

Of course, these trials are not the only source of data, since many pregnant women are already being vaccinated, and followed in a registry. We have started to get just a little bit of information already about safety from this, although nothing published yet. The best thing I could find was evidence from a presentation at the Advisory Committee on Immunization Practice (ACIP). I’ve included a Twitter screenshot below (thank you @brennahughesmd) and the whole presentation is here.

Brenna Hughes @brennahughesmd
#ID and #pregnancy Twittersphere!! It’s finally here!! ACTUAL #COVID19vaccine #pregnancy #safety #data presented at #ACIP today. Side effects same as gen pop. AND pregnancy data reassuring from small sample of #vSafe @CDCgov @acog @MySMFM @idsog_org

The data here is based on about 275 completed pregnancies among about 2000 people currently enrolled in the registry. So, it’s a small sample still, but we’re starting to get some evidence. The table shows the comparison of adverse events for women who were vaccinated while pregnant (the right hand column) to the background risks (left hand column). The data are reassuring; adverse event rates are similar in the two groups. Clearly, we need more sample size, but early data is good.

I will note, finally, that at this point a lot of pregnant people have been vaccinated (way more than are in the registry). And we haven’t seen reporting on adverse effects, even anecdotally. This isn’t data, obviously, but it’s valuable in a sense as “absence of data.”