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Home » COVID-19 vaccine and pregnancy – expert recommendations on safety

COVID-19 vaccine and pregnancy – expert recommendations on safety

One of the questions that keep entering the discourse on the COVID-19 vaccine is whether it should be given during pregnancy. There’s not a definitive answer, but there is some good advice based on evidence from leading infectious disease experts.

I’m not here to make a recommendation one way or another regarding whether the COVID-19 vaccine should be given during pregnancy. My job is to provide the evidence and the recommendations so that every woman can be armed with this when speaking to their healthcare provider.

COVID-19 vaccine pregnancy

The mRNA vaccines will not change DNA

One of the big myths being pushed by the anti-vaccine crowd is that somehow the COVID-19 mRNA vaccines will harm one’s DNA. Of course, during pregnancy, that myth would make one wonder if it harmed the fetus’ DNA.

As I have written, this myth is about as close to “impossible” as one can say about anything in medicine. There is no plausible way that the mRNA in vaccines will have any effect on your or your baby’s DNA. 

In case you don’t feel like clicking on the links above, let me repeat what I’ve written previously. 

The Pfizer and Moderna Therapeutics COVID-19 vaccines are mRNA vaccines that rely upon an mRNA, or messenger RNA, fragment to induce an immune response. However, it does not do this directly.

Normally, during the process called transcription, RNA polymerase makes a copy of a gene from its DNA to mRNA as signaled by the cell. In other words, the mRNA sequences in the cell usually correspond directly to the DNA sequences in our genes. These mRNA sequences “carry” that genetic message to a ribosome for translation, where tRNA triplets, which code for one amino acid, attach to the appropriate mRNA triplet, adding one amino acid to the protein chain. 

As in DNA, genetic information in mRNA is contained in the sequence of nucleotides, which are arranged into codons consisting of three ribonucleotides each. Each codon codes for a specific amino acid, except the stop codons, which terminate protein synthesis.

AT this point, note that the mRNA does nothing to the DNA strand in your genes – it merely reads the sequence.

mrna vaccines

Once the mRNA has created a protein, it is then ripped apart by enzymes in the cell, so that the individual RNA nucleotides can go back to being reused in a whole new mRNA sequence. The cellular machinery of translating DNA into proteins is constantly recirculating itself.

So, let’s summarize. The mRNA vaccines make use of the cell’s ribosome to create the S-protein of the SARS-CoV-2 virus. That antigen induces an adaptive immune system response that will “remember” that antigen allowing the immune system to quickly attack the virus if it shows up.

The mRNA molecule merely reads the DNA information and carries it to the ribosome. It does not change the DNA message in any way, it’s not how the whole process of translation works.

Furthermore, the mRNA from the Pfizer and Moderna vaccines don’t interact with your DNA in any way. They cause the ribosome to produce the S-protein antigen, and that’s it. Once a few copies of that S-protein are manufactured, the mRNA is broken down into individual nucleotides to be reused by the cell. And in case you were wondering, RNA nucleotides are the same whether they’re manufactured by cells or in a test tube. They are molecularly exactly alike.

Repeating this over and over, so everyone gets it.

If mRNA could functionally change the DNA, it would open up a wonderful world of genetic medicine. We could fix all kinds of genetic diseases with this mechanism.

But that’s not how mRNA works, so we can’t.

There are actually other reasons why these mRNA vaccines are not going to affect your DNA:

  1. Your cells’ genome (DNA) is contained within the nucleus of the cell, which is surrounded by a double-membrane. It allows for large molecules, such as mRNA which has read the DNA, to leave the nucleus, but blocks large molecules from entering it. So the S-protein mRNA from the vaccine will not enter the nucleus until it is broken down into individual nucleotides, at which point, they are exactly the same as all of the other nucleotides.
  2. Even if the mRNA molecule could affect the DNA and even if it could get into the nucleus, there are all kinds of error correction machinery in our DNA to keep out random bits of code. With trillions of cells in each human, each containing billions of DNA base pairs, there are naturally a lot of errors that could kill a human if the quality control machinery of the DNA didn’t keep close watch over errors.
  3. Similarly, this mRNA cannot get into the mitochondria (which have their own DNA) and cause damage to its DNA. Even though the mitochondrion lacks a cell nucleus, it does have its own ribosomes and genes, and they would react to the S-protein mRNA in the same ways as the cell – it would not change its DNA.

I think this is one of the biggest concerns regarding the mRNA that I’ve read lately, but this is one myth about the COVID-19 vaccine that should not be of concern to pregnant women. 


Are COVID-19 vaccines safe during pregnancy?

Vaccines are generally not generally tested in pregnant or breastfeeding women, and it was the same with the COVID-19 vaccines. Instead, safety and efficacy data are often gathered through other means, such as animal and observational studies, and these studies are used to weigh the risks and benefits of each vaccination.

There is little biological plausibility that would support a hypothesis that the COVID-19 vaccines would be harmful during pregnancy or lactation. Moreover, there is no evidence that they would pose a risk to developing fetuses or breastfed babies.

There are several reasons why we believe these vaccines are safe:

  1. There were no major safety signals for serious adverse events during the clinical trials of the Moderna and Pfizer vaccines.
  2. Neither vaccine contains a live virus, so there is no way that the vaccine will cause the disease.
  3. The mRNA breaks down quickly and cannot cause harm itself.
  4. The S-protein produced from the mRNA cannot cause harm itself, as it is just a tiny piece of the SARS-CoV-2 virus.

But the most important issue is that the risks of catching COVID-19 during pregnancy probably outweigh the potential risks of the vaccine. Published evidence suggests that pregnant women with COVID-19 are at an increased risk of more severe illness compared with nonpregnant women. For example, COVID-19 may increase the risk of adverse pregnancy outcomes, such as preterm birth.

Furthermore, the COVID-19 vaccine can provide passive immunity to the newborn baby during pregnancy as the antibodies to the virus will be passed from the mother to the baby. This can protect the newborn from COVID-19 until such time that the baby begins producing its own antibodies (if we have a COVID-19 vaccine for children in the future).

What are the expert’s recommendations?

Well, I’m not an expert, so let’s go to the real experts, the American College of Obstetricians and Gynecologists. Their recommendations are:

  • ACOG recommends that COVID-19 vaccines should not be withheld from pregnant individuals who meet the criteria for vaccination based on ACIP-recommended priority groups.
  • COVID-19 vaccines should be offered to lactating individuals similar to non-lactating individuals when they meet the criteria for receipt of the vaccine based on prioritization groups outlined by the ACIP.
  • Individuals considering a COVID-19 vaccine should have access to available information about the safety and efficacy of the vaccine, including information about data that is not available.
  • Pregnancy testing should not be a requirement prior to receiving any EUA-approved COVID-19 vaccine.
  • Pregnant patients who decline vaccination should be supported in their decision. Regardless of their decision to receive or not receive the vaccine, these conversations provide an opportunity to remind patients about the importance of other prevention measures such as hand washing, physical distancing, and wearing a mask.
  • Expected side effects should be explained as part of counseling patients, including that they are a normal part of the body’s reaction to the vaccine and developing antibodies to protect against COVID-19 illness.

In an article published on 10 December 2020 in the American Journal of Obstetrics & Gynecology MFM, the authors wrote:

There is a theoretical risk for fetal harm from any untested medical intervention and this is no different for COVID-19 vaccines.

Pregnant individuals should be given the opportunity, along with their obstetric provider, to weigh the potential risk of severe maternal disease against the unknown risk of fetal exposure, and make an autonomous decision about whether or not to accept vaccine until pregnancy safety data are available.

FDA-approved COVID-19 vaccines should not be withheld from women solely based on their pregnancy or lactation status, when they otherwise meet criteria for vaccination. Considering data available regarding increased maternal morbidity and mortality associated with COVID-19 infection in pregnancy, withholding FDA approved vaccines from this population based on theoretical risks would be unethical.

Of course, these recommendations make it clear it’s a decision process that must weigh the potential benefits of preventing COVID-19 compared to potential risks of the new vaccines. 

There are serious risks to pregnant women and their developing fetus, based on a lot of published, peer-reviewed evidence. And there does not appear to be serious risks to the COVID-19 vaccine during pregnancy.

Weighing those two sides of the equation may seem difficult, but women should take their advice from their physician and certainly not from anti-vaccine websites.

I know it’s a tough decision, but it appears that the benefits of the COVID-19 vaccine during pregnancy far outweigh the risks.

Update 17 February 2021

In an interview with the JAMA Network, White House health advisor Dr. Anthony Fauci stated that there have been “no red flags” seen in the more than 10,000 pregnant women who have received either the Pfizer or Moderna COVID-19 vaccines.

There have been “no red flags” seen in the more than 10,000 pregnant women who have received Covid-19 vaccine shots so far, White House health advisor Dr. Anthony Fauci said Wednesday. During the interview, Dr. Fauci said:

The FDA, as part of the typical follow up you have following the initial issuing of any [emergency use authorization] have found, thus far, and we’ve got to be careful, but thus far, no red flags about that, about pregnant women.



Michael Simpson

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