Someone explain the science: pregnant and Pfizer

[Anonapapple]

I reluctantly went along to get my vaccination on Thursday. I was quite sure that I wasn't pregnant but did a pregnancy test in the morning to rule it out and it was negative. Got the shot and when I got home, noticed that a faint second line had developed. 4 subsequent tests have confirmed that I am pregnant, but it's very early days. My next period is due on Thursday, so the baby must literally have implanted when I got the vaccine. I was 8dpo.

I know the advice is for all pregnant women to get vaccinated but I wouldnt have gone through with it had I have known I was pregnant.

My next dose (pfizer) will be at 8 weeks. I just don't know what to do! I am going to speak to a dr soon but where I live (not in UK) they are not offering it to all pregnant women as standard, but on a case by case basis. I felt conflicted going through with the first one, and now feel even worse.

Can someone with scientific understanding please explain to me how the Pfizer mechanism works in relation to pregnancy?

Does anyone have first hand experience of having had Covid in pregnancy or knowing a pregnant woman who had Covid in pregnancy, and what were the outcomes? Last year the literature was saying that pregnant women were not at heightened risk and now they are?

Can someone please give me some advice?

I’m 21 weeks and had the moderna vaccine 2 weeks ago. Baby is fine and I just had a sore arm for a few days.

In a nutshell the Pfizer and moderna jabs have been chosen for pregnant women because there is data that over 100k pregnant women have had it with no ill effects in the USA.

I found it most helpful to read the below RCOG leaflet, as well as watch the Pregnant Then Screwed webinar which had scientists and doctors answering people’s questions:

www.rcog.org.uk/globalassets/documents/guidelines/2021-02-24-combined-info-sheet-and-decision-aid.pdf

I hope this helps!

Oh also, here’s a link to some info on the study which was done on pregnant women and covid, which shows increased risks. The reason the advice has changed is because of more research being done over time:

www.google.co.uk/amp/s/www.bbc.co.uk/news/health-57193361.amp

Last year the literature was saying that pregnant women were not at heightened risk and now they are?

Pregnant women are at slightly higher risk of falling seriously ill with covid - the risk is elevated mainly in the 3rd trimester
www.rcog.org.uk/en/guidelines-research-services/guidelines/coronavirus-pregnancy/covid-19-virus-infection-and-pregnancy/

As far as "mechanism" goes - all vaccines operate in the same way - they introduce an innocuous substance that matches a key part of the virus in question, into your body that your immune system will attack. In learning to attack the vaccine, your immune system has now been trained to attack the virus, should you get infected.

With the mRNA vaccines, rather than carry in this substance, they contain a strand of mRNA that tells your body's cells to produce it. The antigen in question is the spike protein of the coronavirus, however on its own it's harmless and cannot reproduce.

The side effects that some people experience, are not because of the actions of this spike protein or the mRNA, but people's own immune systems - because they have been called into action, sometimes they trigger some of these mild flu-like symptoms in order to get people to rest and let their body fight the "infection". In essence your immune system doesn't know the difference - it acts like it's facing a live virus.

No vaccine ever produced has interfered with a pregnancy, nor is there any biological reason for it to do so.

@Cafeaulait27 thank you.
The fact that the research about Covid in pregnant women has changed is making me wonder whether the research on the safety of the vaccines in pregnant women will change too. Hope that makes sense. The medic who I spoke to at the vaccination centre told me that while the evidence suggests that the vaccine in pregnancy is safe, nobody really knows for sure. And that is true. All if the literature has careful language such as 'at present', 'the evidence currently shows' etc etc.

@strangeshapedpotato thank you very much for that! You seem to have a good understanding of how the vaccines work. Please could you explain what you mean by 'nor is there any biological reason for it to do so'. This is what I am wondering about.

My worst case scenario is that the vaccine will cause some kind of deformities, or predisposition for the baby to have certain illnesses later in life. I really want to understand the biology behind it. I want to go into this second vaccination fully understanding what's happening.

I dont have a scientific background which makes me feel a bit vulnerable, especially when the rhetoric is often akin to 'dont worry your pretty little head about it, the scientists have everything under control'. The scientists are doing a fantastic job, by the way, not claiming otherwise at all, but I just need to know the ins and outs of why it's safe, at the molecular level.

I just feel like I need a colour-by-numbers explanation as to how the vaccine could not harm the baby. Hope that makes sense!

I will check out all of the links that have been shared with me so not trying to be lazy here, but have been trying to find very specific answers and cant find them.

I had Pfizer.

Thanks to anyone kind enough to humour a scientifically illiterate but concerned pregnant woman 🙂

I had Covid in second trimester and only had mild cold symptoms. Baby was born 6 weeks ago and is fine xx

The medic who I spoke to at the vaccination centre told me that while the evidence suggests that the vaccine in pregnancy is safe, nobody really knows for sure. And that is true

The same is true for paracetamol, having sex, even eating toast

You can observe large groups of pregnant women taking paracetamol or getting vaccines and see that there are no ill effects

But that’s not the same as knowing for certain it is safe

The problem is that the scientific basis for ‘totally safe’ is basically ‘can be proven it won’t do any harm’
Which is more or less impossible to ever prove in a study

But most people’s understanding of ‘safe’ is ‘highly unlikely to do anything bad’ which is of course what vaccines are

Just like we say our roads are safe and our houses are safe, despite a lot of people coming to harm on and in them every year

But when a scientist says they can’t say for certain something is safe, we take that to mean something different to what they mean

@OneOffAsIdentifiable congratulations and 5thanks for the feedback!

@GappyValley thank you. With the toast analogy, do you mean that there might be a small chance that a pregnant woman would maybe eat mouldy bread and get sick, or some kind of anomaly like that. Or that sex might possibly bring on early labour or give a woman an STD while pregnant? Am just trying to get a good understanding here of what the safety jargon really means. Hope that makes sense.

I mean that we can take a very educated guess that eating toast is safe because we’ve observed millions of pregnant women eat toast and not come to harm
But it’s the old ‘absence of proof is not proof of absence’ - we can’t categorically say there is zero chance of a pregnant woman or the baby being harmed by eating toast. We can say we can’t see any biological mechanism by which it would cause harm - like pp said about the vaccine

It’s a bit like the arguments about drinking during pregnancy
The official line is that there is no safe level of alcohol consumption during pregnancy
Some people will take that to mean ‘any and all levels of alcohol consumption are dangerous’ when what it actually means is ‘we haven’t proven there to be zero effects from drinking half a glass of wine a week and therefore can’t call it safe’

It really just comes down to that in day to day life, we all use ‘safe’ to mean ‘highly unlikely to come to any harm’ - riding a bike, driving at 30mph, eating fruit - we would all call those safe activities but people die from them all that time

However scientists have a much higher bar of what can be described as safe, especially relating to pregnancy, so we suddenly get on high alert when a scientist won’t go on the record as describing something as safe, because we assume that means it must be dangerous
What it actually means is it isn’t proven to be risk free. But nothing in life can be proven to be risk free

I forgot about choking on toast!
Thank you, that is all making more sense now.

In terms of the biological mechanisms...does the Pfizer type of vaccine get into the cells of the baby as well? I understand the spikes cant get into the nucleus of the cell but the outer bit. My baby is about the size of a dot now so not sure how it works 😄.

Recent studies show that getting Covid while pregnant more than doubles the risk of both stillbirth and prematurity.

Getting the vaccine when pregnant seems like the much better choice.

MRNA vaccines contain a code ( the instructions )for your body to read which tells your body how to make the correct antibodies to fight the real virus should it ever come into contact with it. This type of vaccine does not contain any part of a live or even dead version of the full virus particle.

One the vaccine / code is read by your body it very quickly breaks down and is gone from your body , with only the memory of how to read the instructions left.

This makes it "safe" because there just isn't anything in the vaccine itself to hang around and cause a problem. Now you might feel a bit ill as your body still has to go through to process of making antibodies and reacting to what it has read, but that is not the same as getting ill because its fighting the full on virus.

Thanks @ChimneyPot and @Bigwave.
I am going to make an appointment with a doctor soon and see what they say. I will be travelling back to the UK this summer and am a teacher so those two factors are swaying me towards getting it.

@Bigwave silly question, but does the baby's body read the code? I will be 8 weeks by the time I have the vaccine.

[quote Anonapapple]@Bigwave silly question, but does the baby's body read the code? I will be 8 weeks by the time I have the vaccine.[/quote]
From Harvard:

www.health.harvard.edu/blog/wondering-about-covid-19-vaccines-if-youre-pregnant-or-breastfeeding-2021010721722

Important points about mRNA vaccines:

-When studied during animal tests, the mRNA vaccines did not affect fertility or cause any problems with pregnancy.
-In humans, we know that other kinds of vaccines generally are safe for use in pregnancy — in fact, many are recommended. The immunity that a pregnant individual generates from vaccination can cross the placenta, and may help keep the baby safe after birth.
-mRNA vaccines do not contain any virus particles.
-mRNA particles used in the vaccine are eliminated by our bodies within hours or days, so these particles are unlikely to reach or cross the placenta.

My worst case scenario is that the vaccine will cause some kind of deformities, or predisposition for the baby to have certain illnesses later in life.

The vaccine is only present in your body for a very short timespan - most of it is gone within a few hours, although depending on where it lodges it can take a few days to completely be gone.

As I said, the side effects are all down to your immune system. People here fall into 3 categories:

1. No side effects other than perhaps a sore arm where injected.

2. General, feeling under the weather side effects (by far the most common type) - these are simply your immune system saying to you "Hey, we got a possible problem here and we need all your energy to fix it, so can you just lay down and rest, and stop doing active stuff...."

3. Serious side effects - very rare. There are two types - the first is immediate - an allergic reaction to the vaccine itself.

The second is even rarer, where the vaccine results in your immune system creating antibodies that attack things they shouldn't. With the AZ jab, this is believed to be the cause of the blood clots. The vaccine (or an impurity in the vaccine) interacts with blood platelets (mechanism uncertain) resulting in the formation of antibodies that attack a specific protein in the platelets, which then triggers clotting. While this kind of thing is alarming, it's important to note that firstly it's extremely rare, and it's ONLY been observed with the adenovirus based vaccines such as the AZ one.

The reason it's important to point out that all the side effects are caused by your body's own immune system, so you understand why problems coming to light in the far future just isn't possible with vaccines.

With other meds, problems can show up either because you are continuously taking the med over a long period of time and damage builds up, or because the med is not eradicated from your body, and it accumulates over time. Neither is the case with vaccines. The short lag with blood clots simply reflects the time it takes your immune system to build up its antibody response - that's the cut-off for any possible side effects to show up.

@strangeshapedpotato @leafyygreens

Thank you so much! That has been very useful.

Am watching the Pregnant But Screwed video now.

Just to add, Covid is not just a risk for you in third trimester - it doubles your risk of stillbirth and preterm labour (from RCOG) I had a very high risk pregnancy due to a previous stillbirth last summer and my fetal medicine consultant explained that they believe the clots Covid can cause in the body can affect the placenta, this is still rare but would absolutely have been enough to convince me to get the vaccine in pregnancy if it was available to me at that time.

@Poppy709 I am so sorry to hear of your loss. That must have been devastating. My waters broke at 36+3 weeks with my last baby and she was born 2 days later so I am at a higher risk of delivering early this time too, I think.

Other people have nicely unpicked the linguistic issues with ‘safe’.

The other slippery word is ‘harm’. We, know, for example, that if you get a fever in pregnancy (or the baby does in the first few months of life) the body slows down making teeth and bones. That shows as a mark, visible when you cut the tooth open. It’s called enamel hypoplasia. If you’re really unlucky it can be on the surface of the tooth, and so visible when you smile.

The vaccine causes fever. So I can see a mechanism where you get the vaccine, you get a fever, and the baby gets a faint mark on the teeth forming at the time. The vaccine has harmed your baby!

Is it harm you care about? Maybe. Maybe not. But until everything like that has been researched and excluded, no one can say with confidence it won’t cause harm.

Hopefully the links others have shared are at least somewhat reassuring. As others ha e said, this has been extensively used in pregnant women in the US with no issues so far. Whereas we know covid caries risks to you and your baby.

@Motorina

Other people have nicely unpicked the linguistic issues with ‘safe’.

The other slippery word is ‘harm’. We, know, for example, that if you get a fever in pregnancy (or the baby does in the first few months of life) the body slows down making teeth and bones. That shows as a mark, visible when you cut the tooth open. It’s called enamel hypoplasia. If you’re really unlucky it can be on the surface of the tooth, and so visible when you smile.

The vaccine causes fever. So I can see a mechanism where you get the vaccine, you get a fever, and the baby gets a faint mark on the teeth forming at the time. The vaccine has harmed your baby!

Is it harm you care about? Maybe. Maybe not. But until everything like that has been researched and excluded, no one can say with confidence it won’t cause harm.

Hopefully the links others have shared are at least somewhat reassuring. As others ha e said, this has been extensively used in pregnant women in the US with no issues so far. Whereas we know covid caries risks to you and your baby.

You make a fair point Motorina, although you may want to watch your wording because on first reading it sounds like you're saying, "If you take the vaccine, you will get a fever and that will mean your kid will have faulty teeth!"

When what I think you are trying to do is outline a possible (albeit highly unlikely) mechanism by which harm could occur.

Side note, I'm not aware of any direct connection between "fever" and enamel hypoplasia, although infection has been mooted as a possible factor - typically though it's genetic isn't it? Do you have a source for that?

Yes, exactly that. A hypothetical mechanism by which the vaccine might increase the risk of a relatively rare condition. Technically, therefore, harming the baby. Although probably not what most of us think when we hear ‘risk of harm’

My broader point is to exclude this possible risk - and all the other possible risks - would take decades of research, even if it could be done. So, when doctors say, “it hasn’t been proved safe” then they’re right. But that’s a long way from “you need to worry”.

(Aside: Guys dental hospital leaflet indicating fever as a possible cause. www.guysandstthomas.nhs.uk/resources/patient-information/dental/Your-child's-molar-incisor-hypomineralisation.pdf)

Try this link. The above has included the closing bracket, so it won’t work. www.guysandstthomas.nhs.uk/resources/patient-information/dental/Your-child's-molar-incisor-hypomineralisation.pdf

Try this link. The above has included the closing bracket, so it won’t work. www.guysandstthomas.nhs.uk/resources/patient-information/dental/Your-child's-molar-incisor-hypomineralisation.pdf

Definitely check in with your GP. As far as I am aware, pregnant women are advised to take the first dose as should provide enough protection from Covid without much of a side effect. The second one is essentially a booster but people seem to have a bit more of a reaction in the sense of getting a fever so the advice is to hold off on the second until after baby is born as you getting a fever could cause harm to the baby.

This is anecdotal as my friend is 20 something weeks and she was advised to wait for the second. I happened to be with SIL at the time my friend sent the message. SIL is a NHS worker and does the vaccines so I asked her why this was the case.