When is the best time in #pregnancy to get the #CovidVaccine?


Two studies came out this week that tackle the question. And (bonus!) which vaccine to go for...

But first! I should say that all the *safety* data says that it's equally safe to get the vaccine in any trimester.

So the question here is really when it's most *protective* to get the vaccine.

Links to safety data here... 2/

The first study, from @EdlowLab, looked at 158 people vaccinated in pregnancy, broken down by vaccine type and trimester of vaccination. 3/

They came back about two months later to see how good of an antibody response the person had made and then again when the baby was born to look at the antibodies in the baby. 4/
People vaccinated with Moderna and Pfizer had more antibodies than those vaccinated with Janssen...

... and so did their babies. 5/ Figure from the paper showing that people vaccinated with Pf
Although the difference was quite subtle, looking at multiple measures of antibody function, people who were vaccinated in the first or third trimester had more functional antibodies than those vaccinated in the second. 6/ Figure from the paper showing that people vaccinated in the
Looking now at the babies... those born following vaccination in the first or second trimester had the higher transfer of antibodies... 7/ Figure from the paper showing that the transplacental antibo
*But* because antibody levels decline over time, the babies born following vaccination in the first trimester have a somewhat lower *absolute* level of antibody. 8/ Figure from the paper showing the absolute level of antibody
The authors conclude...

"These results support vaccination early in pregnancy to maximize maternal protection throughout gestation, without compromising neonatal antibody protection." 9/
A second paper looked at antibody levels in the babies of 171 people vaccinated in the third trimester. Did *when* in the third trimester they were vaccinated make a difference? 10/

Vaccination earlier in the third trimester resulted in better transfer of antibody across the placenta. 11/ Figure from the paper showing higher levels of antibody tran
So from all this, when is the best time in pregnancy to get vaccinated against COVID?

If we want to maximise both antibody functionality and post-birth antibody levels in the baby, we would probably say early third trimester...

BUT... 12/
Antibody protection for the baby after birth is really a bonus. The main reason to get vaccinated in pregnancy is to avoid the increased risk of preterm birth and stillbirth that comes with catching COVID in the second half of pregnancy. 13/
Waiting til early third trimester could leave you unprotected for part of this window of vulnerability. So ideally you want to be protected earlier than that.

My view, while case rates are high, is that sooner is better. 14/
Bonus! My colleague @jackie_parchem is surveying her O&G friends to see what they think about timing of boosters in pregnancy. Let's see if they think they same...


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More from @VikiLovesFACS

17 Nov
How can we know that #COVID19 #vaccines will not harm #fertility? Could an effect unexpectedly appear years into the future?


Let’s start with the data we have on fertility right now.

👉🏻 No reduction in pregnancy rates in vaccinated (vs unvaccinated) ppl in clinical trials.

👉🏻 Egg quality, fertilisation rates and pregnancy rates are the same in vaccinated and unvaccinated IVF patients. 2/
👉🏻 No difference in sperm quality before vs after vaccination. 3/
Read 13 tweets
17 Nov
"I'm #pregnant, and I've been offered a #CovidVaccine #booster. Should I accept?"

@RCObsGyn encourage all pregnant ppl in the UK to get their booster when they are offered it... 1/

rcog.org.uk/en/guidelines-… The JCVI advises that the booster vaccine dose should be off
If you are in the USA and pregnant or recently pregnant, you will be offered a booster vaccine as soon as you are six months out from dose 2. And @acog recommends you get it. 2/

acog.org/clinical/clini… Text from new ACOG guidance. ACOG recommends that pregnant a
But what's the evidence that #CovidVaccine #boosters are safe and effective in #pregnancy? 3/
Read 7 tweets
15 Nov
Wondering if #COVID19 #vaccination affects #periods? 💉🩸🤔

So was I!

Preliminary results from my study on this are out today in preprint... 🧵

To answer this question, we recruited two cohorts.

Cohort 1 consists of 250 people recruited before they received their COVID vaccine, who are keeping a record of their periods before and after vaccination. 2/
This cohort will give us an idea of how common it is to experience a menstrual change after COVID vaccination.

But many of them are still tracking their cycles, so we still have to wait for all the data to come in! 3/
Read 16 tweets
3 Nov
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/

Read 10 tweets
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

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