A bunch of people have been in touch about this paper. Has a review of the evidence really raised questions about the safety of the Pfizer #COVID19 #vaccine in #pregnancy?

TLDR: No… 🧵
The paper purports to present a reanalysis of the V-safe pregnancy registry data to the end of February. You can find the original report (which concluded no increased risk of pregnancy complications following vaccination) here… 2/

But before we get into the details of what’s been done here…

There is no need to scry the six-month-old data from Shimabukuro! It was difficult to interpret because of the limited follow-up time, but *luckily* we now have longer follow-up data… 3/

The longer follow-up (which also has more participants) allows us to accurately calculate the week-by-week miscarriage rate following vaccination.

It’s the same as normal. 4/
So what’s going on with this reanalysis you’ve been asking about? It’s a decent length paper in a peer reviewed journal, so I was expecting something reasonably sophisticated… 5/
But actually, it boils down to the argument we saw circulating on social media back in June.

In short, if you ignore almost all the people who are still pregnant, the miscarriage rate looks artificially high. 6/
Here’s some more detail on why we can’t ignore people who are still pregnant when calculating miscarriage rates, and some recalculations showing what happens if you add them back in (the miscarriage rate looks normal again)… 7/
It’s surprising that such a basic error should have made it past peer review (though I don’t actually know this journal: scientist friends, is it even legit?)… 8/
But the consensus, based on the V-safe data we’ve discussed here, plus a further nine studies, is that #COVID19 #vacination in #pregnancy is not associated with increased risk of miscarriage or any other pregnancy complication. 9/
If you would like to read the studies yourself, you can find them (and more!) here… 10/10


• • •

Missing some Tweet in this thread? You can try to force a refresh

Keep Current with Viki Male

Viki Male Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!


Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @VikiLovesFACS

21 Oct
Stressful times (war, famine) are associated with people experiencing more anovulatory and abnormal menstrual cycles.

But what about the pandemic? This paper used data from 18,076 ppl tracking their cycles with @NaturalCycles app to investigate… 🧵

The authors looked at user data entered from March - September 2019 (pre-pandemic) compared to March - September 2020 (Pandemic). They also asked users to rate their stress levels (retrospectively) in the pre-pandemic and pandemic periods. 2/
The average cycle length decreased from 29.4 to 29.q6 days, and the average period of menstruation increased from 4.21 to 4.23 days.

Neither of these changes is clinically significant. 3/
Read 13 tweets
17 Oct
Are you #breastfeeding? Thinking about whether to get the #COVID19 #vaccine?


This is a thread for you!

People who are breastfeeding can sometimes get forgotten in the focus on pregnancy. But your questions matter too! And I particularly want to make space to address those questions because a lot of people have contacted me, worried about one particular blog post... 2/
I'll get to that later. But let's start by saying that @RCObsGyn and @MidwivesRCM recommend the COVID vaccine if you are breastfeeding. 3/

Read 18 tweets
14 Oct
Wondering if antibodies raised against #COVID19 #vaccines can bind to the placental protein syncytin-1 and harm #fertility?


Out yesterday! More data that addresses this question!

Spoiler alert: they don’t... 🧵

But why would anyone even think that such a thing might happen? Is it even worth researching?

The rumours that COVID19 vaccines would impact fertility were started by a vaccine skeptic who proposed that this might occur, so this is something that a lot of ppl may have heard. 2/
People who work in this area never thought this was very likely, for a number of reasons.

Not least, if this did happen COVID 🦠 would be associated with infertility or problems in early pregnancy, and luckily we don’t see that. 3/

Read 7 tweets
12 Oct
A question I get asked *a lot* is…

“What are the long-term effects on babies born after #COVID19 #vaccination in #pregnancy?”

So let’s talk about what we know… 🧵
Let’s start by looking at the effects at birth. We now have eight large datasets from four countries looking at almost 79,000 people vaccinated in pregnancy. The outcomes for the babies are all normal. 2/
(The CDC has recently put out data from 2 more US studies, bringing the total to 10. But there is some overlap between the participants in these studies and the ones quoted above, so I didn't add those in as unique participants.)

From V-safe... 3/

Read 12 tweets
28 Sep
Let's take a look at the data from the @CDCgov ACIP meeting last week on #COVID19 #vaccine safety in #pregnancy.

It continues to be reassuring!

First, let's take a look at the new data from the V-safe pregnancy registry... 🧵

As of the 13th September, the registry contained 5096 participants. 2/ Among 5096 people in the re...
After they have joined, the participants are interviewed in every trimester, shortly after giving birth, and again when their babies are more than three months old. 3/ Participants are interviewe...
Read 9 tweets
8 Sep
This study looked at the effectiveness of the Pfizer #COVID19 #vaccine in #pregnancy.

👉🏻 96% effective vs. any infection

👉🏻 97% effective vs. symptomatic infection

👉🏻 89% effective vs. hospitalisation


A few additional points…

Why is effectiveness vs hospitalisation lower than against all infection? This is the opposite of what we see in larger studies of the whole population, eg. this PHE data… 2/

Very few people were hospitalised (5/10,861 in the unvaccinated group compared to 0/10,861 in the vaccinated group).

This means the confidence interval for effectiveness vs hospitalisation was wide (43 - 100%) which is likely to have lowered the central estimate. 3/
Read 6 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!