@toadmeister Morning Toby! I’m the reproductive immunologist that is quoted in that Sunday Times article, here to provide a bit of context... 1/
@toadmeister The first thing to say is that Yellow Card is very good at detecting serious side effects that don’t usually happen in the absence of vaccination. That’s what it’s designed for and it’s one of the ways we were able to pick up the rare clotting side effect associated with AZ. 2/
@toadmeister What Yellow Card is not so good at is detecting a change in the rate of non-serious events that sometimes happen anyway. People experiencing a heavy period post-vaccine is a good example of such an event. 3/
@toadmeister Partly this is because not everyone will report a heavy period to Yellow Card. That’s why I encourage anyone who notices a change to their period post-vaccination to report it, so that it’s on the record. You can report here... 4/

@toadmeister But even if everyone reports, Yellow Card is still not really set up to answer the question we want to know the answer to: Am I more likely to get (eg.) a heavy period the month of my vaccine compared to any other month? 5/
@toadmeister That’s partly because we don’t have very good data on how common it is for someone who has regular periods to have an unusual period one month. And that’s partly because this is an area that is understudied. 6/
@toadmeister We can design a study to try and work this out (indeed, I have!) but in the interim, one question a lot of people want to know the answer to is: Assuming that some people really do experience a change in their periods post-vaccine, is this something we should be worried about? 7/
@toadmeister The first thing to say to this is that almost all the reports are of short-term (one cycle, sometimes two) changes. So if you do get a funny period post-vaccine, it’s unlikely to bother you for more than a month. 8/
@toadmeister The second thing to say is that, we do know that some other vaccines also have short-term effects on the menstrual cycle, for example HPV and flu. We also know that these vaccines don’t harm fertility (indeed HPV improves it!). 9/
@toadmeister For people who worry that a change to their period means there may be a change to their fertility, hopefully knowing about these other vaccines will set their mind at rest. 11/
@toadmeister I would also encourage people who are worried about this to look at some of the reassuring data we have around COVID19 vaccines and fertility.... 12/
@toadmeister Vaccines didn’t reduce fertility in the clinical trials, or in studies of IVF patients and by March, 4804 post-vax pregnancies had been reported to the CDC. Details here... 13/

@toadmeister I hope that sets the Yellow Card reports on changes to people's periods following vaccination in context for you. 14/14

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More from @VikiLovesFACS

22 Jun
@beverleyturner @toadmeister To tackle your first tweet first. I think you are talking about the data submitted by Pfizer to the Japanese regulator? That Bryan Brindle has recently had a lot to say about? It's here... 1/

@beverleyturner @toadmeister First, it's important to note that Bridle (oops, I gave him an "n" above!) is not the inventor of these vaccines. He is actually working on a rival vaccine.

But in any case, a lot of what he says just isn't true. I talk more about this here... 2/

@beverleyturner @toadmeister It's also worth noting that the biodistribution data we're talking about here is radiolabelled lipids, not (necessarily) vaccine. 3/
Read 15 tweets
15 May
"The UK now says that #pregnant people should be offered the Pfizer or Moderna #COVID19 #vaccines. But I already had my first dose of AZ. What should I do about dose 2?” 🧵
The official guidance says:

“Pregnant women who commenced vaccination with AstraZeneca are advised to complete with the same vaccine.”

But what is the rationale behind this? 2/

The first thing to say is that the reason we are offering Pfizer/Moderna is not because we have any data to say that AZ is unsafe in pregnancy. It’s just that we have *more* data on mRNA vaccines, so we can be more confident of their safety. 3/

Read 15 tweets
14 May
It's another paper on #COVID19 #vaccination in #pregnancy and #breastfeeding, but with a twist...

How does being pregnant or breastfeeding affect responses to variants?

Does being pregnant or breastfeeding change T cell responses? 🧵

The study looked at 30 pregnant, 16 breastfeeding and 57 ppl who were neither, who had been vaccinated with Moderna or Pfizer. Also 22 pregnant ppl and 6 non-pregnant ppl who had caught COVID.... 2/
They started by looking at antibody responses. Notice that we get more anti-Spike antibody in response to vaccination than natural infection.

This has been shown in other studies of COVID19 vaccination in pregnancy. 3/

Read 12 tweets
14 May
@ElonaWise Your decision will depend on lots of factors that are specific to you. How prevalent is COVID in your area? Are you very exposed? Do you have any conditions that put you at increased risk? All of this you can discuss with your care team to make a personalised decision. But... 1/
@ElonaWise I can tell you the pros and cons of vaccination during pregnancy in general. Let's start with the pros... 2/
@ElonaWise 1. Not getting COVID! This is particularly important because catching COVID in late pregnancy is associated with an increased risk of preterm birth, stillbirth and your baby needing to spend time in intensive care. 3/

Read 11 tweets
13 May
Today (for a change!) let's talk about how the #COVID19 #vaccine affects *male* #fertility 👨🏼‍🦰🍆💦

This study looked at the semen of 43 men before and after they were vaccinated. Sperm parameters did not change. 1/

medrxiv.org/content/10.110… Image
The authors also highlight that catching COVID has been associated with a reduction in sperm counts.

In this study 6% of recovered male COVID patients had no sperm, and 18% had less than normal (compared to 1% and 3% in the general population). 2/

They conclude - and I am paraphrasing here - that #COVID19 #vaccination is likely to protect your swimmers. 🏊🏼‍♂️🏊🏿‍♂️🏊🏻‍♂️ 3/3
Read 4 tweets
12 May
This @NEJM paper did long-term follow-up on 3958 #pregnant ppl who received a #COVID19 #vaccine.

👉🏻 No increased risk of pregnancy-specific adverse events (including #miscarriage).

So why are ppl claiming it shows a 24x increased risk of miscarriage? 🧵

The rate of miscarriages reported in the paper is 12.6%.

But is that higher than we would normally see?

No... 2/
The normal range quoted in the paper, based on these references, is 10 - 26%.

The range is large because lots of things affect miscarriage rate, so it varies a lot between studies.

But note the rate in the vaccinated population is within this normal range. 3/
Read 13 tweets

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