"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:

β€œPregnant women who commenced vaccination with AstraZeneca are advised to complete with the same vaccine.”

But what is the rationale behind this? 2/

assets.publishing.service.gov.uk/government/upl…
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/

rcog.org.uk/en/guidelines-…
In fact, between January and April, we were vaccinating pregnant ppl with AZ and tracking safety with the Yellow Card reporting scheme and no pregnancy-specific safety concerns emerged. 4/
But what about that rare clotting-related side effect associated with AZ (called VITT). Aren’t pregnant ppl at higher risk of that, since they are at higher risk of clotting anyway?

Actually, no... 5/
During pregnancy, tendency to clot increases because of increased clotting factors in the blood. Whereas in VITT, platelets are activated by antibodies. So the clotting occurs by different pathways. 6/
There have been no reported cases of VITT in pregnant people. 7/

assets.publishing.service.gov.uk/government/upl…
It’s also worth noting that VITT is very similar to HIT (a reaction to the blood thinner heparin). HIT is actually less common in pregnant than non-pregnant ppl, so it’s even possible that pregnancy puts you at lower risk of VITT. 8/

ajog.org/article/S0002-…
This is why the JCVI recommends getting your second dose of AZ if your first dose was AZ.

But I know some ppl still feel a bit uncomfortable with this, so what are your options? 9/
Right now we do not have enough evidence on mixing and matching vaccines to feel comfortable offering ppl their second dose as an mRNA vaccine if they started with AZ.

So that’s off the table (for the time being, at least.) 10/
Which leaves you with the option of either getting your second dose of AZ or delaying it.

So let’s think about what happens if you delay... 11/
Vaccine efficacy after a single dose is 76% (and 81%) after both doses. So a single dose does give you a good level of protection.

The problem is, it’s unclear how long protection will last without the booster. So that 76% may decline over time. 12/

thelancet.com/journals/lance…
Because of this, I do think the JCVI’s advice, to get dose 2 of AZ, is probably the best course of action. But if you are worried and your personal risk factors for COVID (exposure, medical history) are low, you might consider delaying your second dose until after the birth. 13/
This is a discussion you should have with your care team, who can take into account these personal factors. But I hope the evidence above will provide a useful framework for those making these decisions.

As always, happy to chat about this. 14/14
PS. For signs of VITT, please see this useful graphic.

I’m afraid I can’t remember where I got it from so if anyone recognised it and knows the author, let me know so I can credit!

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More from @VikiLovesFACS

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? 🧡

jamanetwork.com/journals/jama/…
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/

medrxiv.org/content/10.110…
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/

bmj.com/content/370/bm…
Read 11 tweets
13 May
Today (for a change!) let's talk about how the #COVID19 #vaccine affects *male* #fertility πŸ‘¨πŸΌβ€πŸ¦°πŸ†πŸ’¦

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/

ncbi.nlm.nih.gov/pmc/articles/P…
They conclude - and I am paraphrasing here - that #COVID19 #vaccination is likely to protect your swimmers. πŸŠπŸΌβ€β™‚οΈπŸŠπŸΏβ€β™‚οΈπŸŠπŸ»β€β™‚οΈ 3/3
Read 4 tweets
12 May
This @NEJM paper did long-term follow-up on 3958 #pregnant ppl who received a #COVID19 #vaccine.

πŸ‘‰πŸ» No increased risk of pregnancy-specific adverse events (including #miscarriage).

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

10.1056/NEJMoa2104983
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
10 May
"If #COVID19 #vaccines are so safe, why aren't the manufacturers accepting liability for any potential injuries?"

It's a fair question. And it's clearly bothering a lot of people, judging by my inbox.

But actually the answer differs depending on where you are... 🧡
Starting in the UK... πŸ‡¬πŸ‡§

In the mid-70s, ppl became concerned about the potential for long-term injuries associated with the whooping cough vaccine (although it turned out there was no problem). To bolster confidence, the govt passed the Vaccine Damage Payment Act in 1979. 2/
This makes a payment of (now) Β£120,000 to anyone who suffers permanent injury as a result of a govt-recommended vaccination. Following approval, COVID19 vaccines were added to the list of vaccines for which the govt accepts liability under the act. 3/

gov.uk/vaccine-damage…
Read 14 tweets
5 May
There are already lots of studies showing that antibodies pass into breastmilk after #COVID19 #vaccination. But this new preprint looks at the properties of those antibodies in more detail, as well as reporting for the first time on T cells... πŸ’‰πŸ€±πŸΏπŸ§΅

medrxiv.org/content/10.110…
First - in agreement with the other studies - anti-Spike IgA and IgG are found in breast milk following vaccination.

(Milk shown in purple, plasma in orange). 2/
Next, they looked at what kind of IgA it was. Is it monomeric (M) like IgA in blood? Or oligomeric (O), suggesting it is produced at a mucosal surface?

The IgA in milk is mostly oligomeric, suggesting it is produced locally in the breast. 3/
Read 8 tweets

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