The Miscarriage Texts

What Fauci and Walensky discussed privately in January 2021, and what pregnant women were told

The Miscarriage Texts

What Fauci and Walensky discussed privately in January 2021, and what pregnant women were told

This essay is written for both a general audience and expert scientists and physicians interested in this topic. I have been trained as a pathologist and taught pathology (as well as molecular biology) to medical students for many years, and so it should be no surprise that some of the language is rather technical.

For this, I apologize to and empathize with general-interest readers, and ask that you bear with me so I can communicate precisely with experts and policy specialists who may also read the essay. Keep in mind that, until he left the federal government, even Fauci (or one of his minions) used to open and read some of our essays, and on occasion our essays reach and impact policymakers at the highest levels of government.

In March 2026, a group at the University Hospital of Wuerzburg published what they had found in 106 term placentas collected between November 2020 and October 2022. Thirty-one were positive for SARS-CoV-2 spike protein by immunohistochemistry. The staining sat predominantly in Hofbauer cells, the fetal macrophages inside the chorionic villi, and in syncytiotrophoblast, with the trophoblast layer and the endothelium of villous capillaries also involved. Eleven of those positive placentas came from women who had been vaccinated and who reported no infection of any kind during the pregnancy.

No viral RNA was detected in any sample tested. Vaccine RNA was. A Comirnaty probe lit up cells of the decidual surface in one placenta. A Spikevax probe lit up the endothelium of villous capillaries in another, from a woman whose last dose preceded her pregnancy (Bartmann et al. 2026).

That study carries severe limits. It is descriptive work on fixed tissue and cannot establish mechanism. The cohort was drawn from uncomplicated births at term, and the authors state plainly that women with miscarriages were not included, so the study cannot speak to pregnancy loss at all. The RNA findings rest on two samples out of nine tested. And the literature is split: Santos and colleagues reported no spike glycoprotein in placentas after mRNA vaccination, and Prahl and colleagues excluded vaccine traces in twenty placentas by Western blot and PCR.

The finding establishes that the question is real, answerable by experiment, and answerable in human tissue. The compartments where the staining appeared are the compartments that express ACE2, the receptor for the protein being stained. ACE2 is a carboxypeptidase. It degrades angiotensin II to angiotensin 1-7, and in the placenta that reaction governs vasodilation, oxidative balance, and the vascular remodeling on which perfusion depends.

None of this was known when the federal government moved from telling pregnant women they could choose vaccination to telling them they should have it. Nor had anyone looked. The pivotal trials excluded pregnant women, the preclinical biodistribution work was done in nonpregnant rats, and the reproductive toxicity studies measured outcomes rather than tissue distribution.

To be blunt, as a physician/scientist, experienced biological product development and clinical research specialist, I am shocked by this absence of critical data given the policy decisions that followed. This is an example of public health malpractice. <RWM>

What did exist, in January 2021, was a conversation.

On January 25, 2021, five days after the inauguration, Dr. Vivek Murthy, Biden’s nominee for Surgeon General and a senior adviser to the incoming administration’s COVID response, texted Anthony Fauci and newly installed CDC Director Rochelle Walensky. He asked whether any data or theoretical reason favored vaccinating early or late in pregnancy, and when more robust data on risk might arrive. He added that he had been telling pregnant women no concerning outcomes had appeared in the trials, while noting that the number of pregnant subjects was probably limited (The Hill 2026).

Walensky answered first, describing a thin evidence base and pointing to the V-safe pregnancy registry, which by then had enrolled more than 15,000 pregnant women (Tampa Free Press 2026). Fauci replied that there were “no data or theoretical reason” to prefer early over late vaccination (The Hill 2026). He added that some people, including female health care professionals, were uneasy about a genetic vaccine early in pregnancy, and that the concern about effects on genes was a misperception.

Roughly two hours later, he wrote again. He had asked around further, and another issue had come up that the others needed to know about. Because many people experience significant cytokine response and fever after the second dose, this “theoretically could be associated with miscarriage in the 1st trimester” (CNN 2026). Walensky replied that it was a good point, especially after dose two (Forbes 2026). The affirmative federal recommendation that pregnant women be vaccinated was issued on August 11, 2021. Nothing in that exchange, and no equivalent of it, reached the public in the intervening seven months.

That is what makes these texts so consequential.

The scandal is not that scientists discussed uncertainty privately. Scientists are supposed to discuss uncertainty.

The scandal is that uncertainty may have disappeared not because the science had answered the question, but because they believed that the public-health message required certainty.

Pregnant women deserved to know the difference.

And they deserved to know it before they rolled up their sleeves.

What the public heard in the same weeks

On January 26, Murthy flagged the World Health Organization’s recommendation against routinely administering the Moderna vaccine to pregnant women. His stated concern, however, was not whether the WHO was correct. It was what the recommendation might do to pregnant women’s confidence in vaccination.

Fauci’s answer set out the standard he was applying. Where data are lacking in pregnant women, one must weigh potential risks against benefits. COVID can be serious in pregnancy. More than 10,000 pregnant women had been vaccinated with no issues reported. FDA, the CDC advisory committee and the American College of Obstetricians and Gynecologists all left the decision to the individual (CBS News 2026).

That position was defensible and it matched CDC’s clinical guidance, which held that a pregnant woman in an eligible group may choose vaccination. It is also not what he said in public a week later. Speaking with Howard Bauchner, then editor of JAMA, Fauci reported that FDA had found no red flags among the pregnant women vaccinated to that point, and said he would rather take his chances with the vaccine than with infection while pregnant (The Hill 2026).

The private discussion included a plausible mechanism for harm, specific concern about the second dose, and an acknowledgment that the necessary data did not yet exist.

The public discussion emphasized the absence of red flags and offered a personal endorsement.

A week earlier, Fauci had privately identified a theoretical risk of miscarriage. When he spoke publicly, that part of the risk-benefit calculation was gone. The uncertainty had not disappeared. It had simply disappeared from the message.

One mechanism, two registers

Fever is the clinical expression of cytokine release. The mechanism Fauci described privately in January was therefore not a private discovery, and that makes the sequence worse.

CDC’s clinical guidance in December 2020 already advised that pregnant women who develop fever after vaccination may be counseled to take acetaminophen, on the stated ground that fever has been associated with adverse pregnancy outcomes (Newsweek 2020). The agency had accepted the causal premise in print before the first pregnant woman was vaccinated. Fauci’s January text restated the same pathway in mechanistic language and added two specifics: that the response concentrates after the second dose, and that the outcome at issue is loss in the first trimester.

So the agency was not unaware. It published the countermeasure in December, discussed the mechanism privately in January, and by August had dropped the subject. The August 11 statement contained no fever caution of any kind.

A risk that CDC had acknowledged in its own guidance eight months earlier stopped being mentioned precisely when its recommendation became universal.

Evidence ran the other way too. The April 2021 registry analysis found that pregnant participants reported fever, chills, headache and myalgia less frequently than nonpregnant women of the same ages. Of the whole inflammatory pathway, reactogenicity was the one element CDC measured, and the measurement was reassuring. That finding belonged in the public conversation as much as the caution did, and neither appeared in August.

Since these texts became public, the mechanism has been misdescribed in both directions. Post-vaccination fever is a finding consistent with a cytokine-mediated systemic response. In most recipients, that response is transient reactogenicity and nothing more, and anyone claiming these vaccines routinely produce cytokine storm is misusing a term that names a defined pathological syndrome.

But a pathologist asks a different question, and that question does not appear to have been asked at all.

Any biological insult applied across a large population produces a distribution of host responses. Clinically important events often occur in the tails of that distribution, not at its mean. A reassuring average therefore cannot, by itself, exclude an uncommon susceptible subgroup.

The relevant question was not whether the average pregnant woman experienced a cytokine storm. She plainly did not. The question was whether the inflammatory response following vaccination could become sufficiently pronounced in some subset of pregnant women to alter pregnancy risk, particularly during the first trimester, and if so, whether those women could be identified.

A woman with an underlying inflammatory or thrombophilic tendency, a history of recurrent pregnancy loss, or some other susceptibility is not the modal recipient. Her risk cannot be inferred simply from the modal result.

That was the safety question hiding inside Fauci’s January text. And before the recommendation became universal, it was a question that deserved an answer.

Why there were no data

Pregnant women were excluded from the pivotal trials of both mRNA vaccines. That exclusion followed a convention in vaccine and drug development that long predated 2020. But its consequence was unavoidable: at the moment of authorization, there was no randomized evidence for pregnancy outcomes. And once mass vaccination began, that missing randomized evidence could not simply be recreated after the fact.

What largely replaced it was V-safe, CDC’s voluntary smartphone-based surveillance system, with a pregnancy registry attached. Participants enrolled and reported their own outcomes. A registry of that design can be useful for detecting a large safety signal quickly. But it is not a randomized trial. It cannot by itself establish a population rate without an appropriate denominator, it has no contemporaneous unvaccinated control group, and it necessarily reflects the women who enroll and continue reporting.

Those limitations do not make the data worthless. They define what conclusions the data can support.

On August 11, CDC told pregnant women the vaccines were safe and recommended vaccination. Twelve days later, FDA approved Pfizer's vaccine while still requiring the company to conduct the pregnancy study necessary to characterize pregnancy and infant outcomes.

And that distinction matters, because much of the reassurance offered about vaccination during pregnancy in the critical months between December 2020 and September 2021 rested on precisely this kind of observational surveillance.

The government was not reassuring pregnant women on the basis of evidence generated in pregnant women before authorization. It was vaccinating them first and accumulating the pregnancy safety evidence afterward.

By any recognizable standard of medical and research ethics, this is profoundly troubling. It runs directly against the Preles of informed consent and protection of human subjects embodied in the Nuremberg Code, the Declaration of Helsinki, and the Belmont Report.

Suspending the default

Pregnancy medicine has traditionally operated from a precautionary default. When adequate evidence of safety is absent, exposure to a new drug or biological product is approached cautiously. Thalidomide and diethylstilbestrol helped build that posture, and modern federal labeling rules preserve the underlying principle by requiring labels to state when human pregnancy data are unavailable. The reason is obvious: pregnancy is precisely the circumstance in which controlled experimentation is difficult and the cost of guessing wrong may fall on someone who never consented.

Fauci identified the principle that could override that default. Where data are lacking in pregnant women, he wrote on January 26, potential risks must be weighed against potential benefits.

That is the correct standard.

But performing such a calculation requires both sides of the equation.

The harm term was largely unquantified because the pivotal trials had excluded pregnant women. The benefit term rested principally on the risk COVID posed to the mother, and CDC had attempted to measure that.

Zambrano and colleagues, reporting in November 2020 on 409,462 symptomatic women aged 15 to 44, found that pregnant women were more likely than nonpregnant women to be admitted to intensive care, at 10.5 versus 3.9 per thousand; to receive extracorporeal membrane oxygenation, at 0.7 versus 0.3 per thousand; and to die, at 1.5 versus 1.2 per thousand. The adjusted risk ratios were 3.0, 2.4, and 1.7, respectively.

Their own summary captured an important distinction: although the absolute risks of severe outcomes were low, pregnant women were at increased relative risk for severe illness.

Both statements were true. Only the second traveled.

Consider mortality. The observed difference was 0.3 deaths per thousand symptomatic infections, or three additional deaths per 10,000. CDC’s earlier June 2020 analysis had found mortality among pregnant women statistically indistinguishable from nonpregnant women of the same ages, with an adjusted risk ratio of 0.9.

The November report contained another comparison that received considerably less attention. Citing the 2009 H1N1 pandemic, its authors noted that the absolute risks of severe outcomes among pregnant women during H1N1 exceeded those then being observed with COVID-19.

There was another curious feature in the COVID data.

The relative risks diminished as the endpoints became harder: ICU admission carried an adjusted risk ratio of 3.0, ECMO 2.4, and death 1.7. In the earlier June analysis, death had carried a ratio of 0.9 and had not reached statistical significance.

That pattern does not prove bias. But it should have raised an obvious question about how much of the apparent elevation reflected biology and how much reflected clinical decision-making.

ICU admission is not purely a biological endpoint. It is also a clinical decision, and obstetrics has long maintained a lower threshold for escalating care because the physician is managing two patients and fetal monitoring may be easier at higher acuity.

ECMO introduces another selection problem. Candidacy favors younger patients without major underlying disease, characteristics disproportionately represented among pregnant women. A higher rate of receiving ECMO therefore does not necessarily translate directly into an equivalent increase in underlying disease severity.

The clinical environment could reinforce these effects. Throughout 2020 and 2021, physicians were repeatedly told that pregnancy was a high-risk condition for COVID-19, with these same surveillance figures offered as evidence. That creates the possibility of a feedback loop: clinicians expecting greater risk may admit or escalate pregnant patients sooner, and those admissions then enter surveillance datasets as evidence of greater risk.

CDC acknowledged a version of this problem one level down. Its data could not reliably distinguish hospitalization because of COVID deterioration from hospitalization for another reason, including delivery.

The COVID-NET hospitalization surveillance report from September 2020 illustrates the problem. Among 598 hospitalized pregnant women with laboratory-confirmed SARS-CoV-2 infection, 54.5 percent were asymptomatic on admission. Many had entered the hospital for obstetric care and were discovered to be infected through testing.

Two further limitations appear in the November report’s own footnotes. Death information was missing for 22.0 percent of pregnant women and 17.2 percent of nonpregnant women, with those missing outcomes assumed to represent survival. ECMO information was missing for roughly 78 percent of both groups, with missing values assumed to mean ECMO had not occurred. Importantly, the missingness on the mortality variable differed between the groups.

None of this establishes that pregnancy carried no additional COVID risk.

There were sound biological reasons to suspect that it might. Pregnancy reduces functional residual capacity, elevates the diaphragm, increases oxygen consumption, produces a hypercoagulable state, and alters immune function. Influenza had already demonstrated that respiratory infections can behave differently during pregnancy.

Zambrano also restricted the analysis to symptomatic women, reducing part of the ascertainment problem.

And the subsequent literature was not uniform. A prospective single-center comparison of obstetric and non-obstetric COVID cohorts in India found no difference in ICU admission, length of stay, or mortality, and significantly less need for ventilatory support among pregnant patients, although differences between the cohorts limit what can be inferred from that comparison (Kumari et al. 2022).

The point is not that CDC had demonstrated there was no additional maternal risk.

The point is that it had not measured that risk with anything approaching the precision implied by the public message.

Its estimates were influenced by endpoints partly determined by clinical judgment, generated within a clinical environment already primed to regard pregnancy as high risk, and accompanied by important missing-data and ascertainment limitations.

Yet those estimates supplied the benefit side of the calculation used to overcome the precautionary default.

Those qualifications persisted into the September 2021 advisory. Its 161 deaths among more than 125,000 confirmed cases corresponds to roughly 1.3 deaths per thousand, broadly consistent with the absolute mortality Zambrano had reported a year earlier. Its more striking figure, that approximately 97 percent of hospitalized pregnant patients were unvaccinated, included hospitalization for COVID illness or for labor and delivery, as the advisory itself acknowledged.

What reached the public were principally the counts and relative risks. The absolute rates, uncertainties, endpoint problems, and confounders remained largely buried in the underlying literature.

Meanwhile, the other side of Fauci’s equation remained poorly characterized.

The mistake was not literally assigning vaccine risk a value of zero. It was allowing an absence of adequate evidence of harm to function, increasingly, as evidence of safety.

That distinction is especially important in pregnancy.

A risk-benefit calculation can tolerate uncertainty when uncertainty exists on both sides, but it cannot manufacture a missing quantity. If the potential benefit is estimated from imperfect observational evidence while the potential harm cannot yet be reliably measured, the result is not a conventional risk-benefit calculation. It is a decision made under profound uncertainty.

And profound uncertainty is precisely why the precautionary default exists.

Invoking risk-benefit analysis to override a precaution designed for circumstances in which one side of that analysis cannot yet be adequately measured turns the purpose of the precaution on its head.

There is an uncomfortable parallel in Fauci’s own public assessment of COVID risk.

On February 8, 2020, his diary recorded a denominator-adjusted case-fatality estimate of 0.2 to 0.3 percent. On February 28, writing with H. Clifford Lane and Robert Redfield in the New England Journal of Medicine, he suggested that the overall clinical consequences of COVID-19 might ultimately resemble those of a severe seasonal influenza, with a case fatality rate perhaps near 0.1 percent.

Less than two weeks later, on March 11, Fauci told the House Oversight Committee that COVID-19 mortality was approximately one percent and that the virus was therefore roughly ten times more lethal than seasonal influenza.

The numbers were being generated from a rapidly evolving epidemic, with an uncertain denominator, so changing estimates were inevitable.

But that is precisely the point.

Uncertainty was treated as grounds for precaution when estimating the virus's danger.

When estimating the danger of vaccination during pregnancy, uncertainty increasingly became a reason for reassurance.

The paper, the denominator, and the correction

On April 21, 2021, Shimabukuro and colleagues published preliminary V-safe pregnancy findings in the New England Journal of Medicine. Among 827 participants whose pregnancies had reached a recorded outcome, 104 had experienced spontaneous abortion before 20 weeks. The paper presented that as 12.6 percent and described the proportion as similar to the background rate in the general population. In the accompanying table, the authors placed a published incidence range of 10 to 26 percent beside it.

There was a serious denominator problem.

A footnote to the same table disclosed that 700 of those 827 women had received their first eligible vaccine dose during the third trimester. By definition, those women had already passed 20 weeks of pregnancy and therefore were no longer at risk of an event defined as spontaneous abortion before 20 weeks.

Including them in the denominator necessarily drives the apparent miscarriage proportion downward.

Put simply, the calculation asked how often an event occurring before 20 weeks happened in a group dominated by women who were already beyond 20 weeks when they entered the analysis.

The resulting 12.6 percent was therefore not a valid estimate of miscarriage risk following vaccination in early pregnancy.

Hong Sun raised this objection in the American Journal of Obstetrics and Gynecology on August 3, 2021. On September 8, three of the CDC authors responded in the New England Journal of Medicine and agreed with the essential point: 827 completed pregnancies was not an appropriate denominator for estimating the risk or rate of spontaneous abortion. Such an estimate needed to be based on women vaccinated before 20 weeks of gestation (Meaney-Delman, Ellington, and Shimabukuro 2021).

On October 14, the journal formally corrected the article. The 10-to-26-percent background comparator beside the spontaneous-abortion figure was replaced with “Not applicable,” removing the comparison that had made the original 12.6-percent figure appear directly comparable with the expected population rate.

There is an important arithmetic trap here, because the opposite error has circulated ever since.

If the 700 third-trimester pregnancies are simply removed from 827, that leaves 127 completed pregnancies. Dividing 104 miscarriages by 127 produces approximately 82 percent.

That number is also invalid.

It fails for the mirror-image reason. The March 30 cutoff preferentially captured early pregnancies that had already ended, while many women vaccinated early in pregnancy were still pregnant and therefore had no completed outcome to enter the denominator. Miscarriages occur earlier than live births, so counting only pregnancies that had already finished at an early cutoff inevitably overrepresents losses.

The original calculation diluted the numerator with women who could no longer miscarry. The 82-percent calculation does the opposite: it excludes many pregnancies that had not yet had time to reach a successful outcome.

Neither 12.6 percent nor 82 percent is a valid miscarriage rate.

The scientifically defensible conclusion from the April dataset was much simpler and much less reassuring than the headline number suggested:

At that point, the registry did not yet contain enough appropriately followed early-pregnancy exposures to calculate a reliable miscarriage rate.

August 11

CDC announced its affirmative recommendation on August 11, 2021, under the headline “New CDC Data: COVID-19 Vaccination Safe for Pregnant People.” The agency cited an analysis of roughly 2,500 women who had received at least one vaccine dose before 20 weeks of pregnancy. It reported no increased risk of miscarriage, with a rate near 13 percent, within the expected background range.

This was, in substance, the corrected calculation. It restricted the analysis to women who had actually been vaccinated during the period in which spontaneous abortion could occur, precisely the denominator problem critics had identified in the April paper.

And its central finding has held up.

Published as Zauche and colleagues on September 8, 2021, the analysis estimated a cumulative spontaneous-abortion risk of 14.1 percent, or 12.8 percent after age standardization, among 2,456 participants. Subsequent studies encompassing more than a million pregnancies have likewise found no overall increase in miscarriage following COVID-19 vaccination.

That evidence matters. But so do the limits of what it established.

The cohort underlying a universal recommendation is therefore worth examining. Of the 2,456 participants, 88.8 percent were health care personnel and 78.3 percent were non-Hispanic white. More than one quarter reported at least one previous spontaneous abortion. Thirty-five women who reported a loss before six completed weeks were excluded from the analysis. That is a methodologically defensible choice, given how frequently very early pregnancy losses go unrecognized in the general population, but it is still a choice that belongs in any description of what was measured.

Composition determines more than whom a study represents. It also affects what the study is capable of detecting.

A cohort composed overwhelmingly of working health care personnel is not necessarily representative of the entire pregnant population to whom a universal recommendation will apply. More importantly, a study of approximately 2,500 pregnancies can provide useful reassurance about a substantial increase in overall miscarriage risk while remaining poorly equipped to identify a smaller increase confined to an uncommon susceptible subgroup.

Those are different questions.

The timing presents another problem. CDC announced the conclusion four weeks before the analysis was published, meaning the public received the answer before outside scientists could examine the methods and data underlying it. The announcement also arrived while the April New England Journal of Medicine paper still stood uncorrected, with its inappropriate denominator and population comparator remaining in print until October 14.

Walensky’s August 11 statement urged all pregnant people, those considering pregnancy, and those breastfeeding to be vaccinated, describing COVID-19 vaccines as safe and effective during the urgency of the Delta wave (CDC 2021a).

But notice the distance between the evidence and the claim.

The new analysis addressed one outcome: spontaneous abortion before 20 weeks, in one voluntary, self-reported surveillance cohort.

The public conclusion was much broader:

COVID-19 vaccination was safe in pregnancy.

Those are not equivalent statements.

On September 29 CDC followed with a health advisory, CDCHAN-00453, calling for urgent action. Its summary stated that CDC “strongly recommends COVID-19 vaccination either before or during pregnancy because the benefits of vaccination outweigh known or potential risks” (CDC 2021b).

The advisory reported more than 125,000 laboratory-confirmed cases in pregnant people, more than 22,000 hospitalizations and 161 deaths as of September 27, with 22 of those deaths in August alone, and noted that roughly 97 percent of pregnant people hospitalized with confirmed infection were unvaccinated. Those figures are serious and they are the strongest part of the case CDC made. The advisory now carries a retired designation in the agency’s own document archive.

The question that was not asked

Fauci’s concern ran from cytokine response and fever to first trimester loss. Fever in early pregnancy is a recognized risk, so the pathway is real, and it is the pathway an immunologist reaches for. It was also the only pathway anyone in that exchange raised.

The antigen these vaccines instruct cells to produce carries biological activity of its own. Spike is a receptor-binding protein, and its receptor had already been mapped to the tissue at issue. Li and colleagues, publishing in PLOS ONE in April 2020 from a preprint that February, reanalyzed roughly 65,000 cells from placentae of six to fourteen weeks and found ACE2 expressed in decidual stromal cells, decidual perivascular cells, villous cytotrophoblast and syncytiotrophoblast. Ashary and colleagues reported that July that syncytiotrophoblast carried the highest proportion of ACE2-expressing cells in the first trimester placenta, and noted that extravillous trophoblast, which acquires ACE2 expression later, is the population that invades the maternal decidua and remodels the spiral arteries.

That map was not new even then. Valdes and colleagues had localized ACE2 and angiotensin (1-7) to syncytiotrophoblast, cytotrophoblast, villous endothelium and vascular smooth muscle, and to invading trophoblast and decidual cells in the maternal stroma, in Placenta in 2006 (Valdes et al. 2006).

The two-proline modification does not change any of this. The substitutions sit at the junction of heptad repeat 1 and the central helix, in the fusion machinery. The receptor-binding domain is untouched. What 2P prevents is the transition to the postfusion state, and receptor engagement occurs upstream of that transition. Wrapp and colleagues established the point in the paper that defined the antigen: their cryo-EM structure showed the predominant state of the stabilized trimer with one receptor-binding domain rotated up in a receptor-accessible conformation, and their surface plasmon resonance measured ACE2 binding at roughly 15 nanomolar, some 10 to 20 fold tighter than SARS-CoV spike (Wrapp et al. 2020). Both measurements were made on the 2P construct. Corbett and Graham of the NIAID Vaccine Research Center are authors on it. The canonical statement that this spike binds ACE2 with high affinity is a measurement of the vaccine antigen.

Spike binding drives ACE2 into the endocytic pathway and lysosomal degradation, an effect mapped to both the receptor-binding domain and S2, and one that tracked with clinical severity across variants. A physiology review of ACE2 in pregnancy states the consequence directly: downregulation of placental ACE2, whether by inhibition or by spike protein binding, produces placental inflammation and oxidative stress, limits fetal growth, and generates the classical picture of preeclampsia.

Whether the antigen reaches that tissue at concentrations approaching its affinity is the operative question, and the arithmetic constrains the argument. Ogata and colleagues measured circulating vaccine antigen after mRNA-1273 and found S1 detectable from day one, peaking on average near 68 picograms per millilitre (Ogata et al. 2022). At roughly 76 kilodaltons that is about 0.9 picomolar, some four orders of magnitude below the 15 nanomolar dissociation constant. In bulk plasma, receptor occupancy would be negligible. The question lives in local tissue concentration, not in blood.

The Wuerzburg placentas are not the only place investigators have found the material since. A team at NYU Langone reported, in a research letter funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, vaccine mRNA in human placental tissue by in situ hybridization, with signal in the decidua and in the villi from recipients of both products (Lin et al. 2024). In pregnant mice given intramuscular mRNA-1273, the construct crossed the placenta within an hour, reached fetal circulation, accumulated in fetal tissue and was translated into spike protein there (Chen et al. 2025). Lipid nanoparticles resembling those in the vaccines transfect placental trophoblast, endothelium and immune cells, which is why an entire field now engineers them deliberately for placental delivery.

The decidua and the villi are where the mRNA was found. They are also where ACE2 sits. What the antigen does to decidual stroma, decidual perivascular cells, villous cytotrophoblast and syncytiotrophoblast has not been characterized, and it was not characterized before pregnant women were told the vaccines were safe for them. The receptor map dated to 2006, the affinity measurement to February 2020 from the antigen’s own designers, and the experiment joining them to the tissue has still not been done.

The same receptor distribution ties together presentations that were handled as separate topics. Decidual stromal and perivascular cells express ACE2. The decidua governs menstrual bleeding, sheds whole in decidual cast shedding, and fails in early pregnancy loss. Through the spring of 2021 women were reporting all three. Kate Clancy and Katharine Lee gathered roughly 130,000 accounts of menstrual disturbance in the same months the pregnancy registry was being assembled. The menstrual reports went to content moderation and to a survey run by two anthropologists. The pregnancy question went to a registry. No federal analysis treated them as observations on one organ.

Redfield

Robert Redfield left the CDC directorship on January 20, 2021, five days before that text chain, and is not a participant in it. He is the third author on the February 2020 New England Journal editorial with Fauci and Lane, and he ran the agency when ACIP voted in December 2020 and when the permissive guidance issued.

On August 11, 2026, responding to the released texts, he said he never thought pregnant women should be vaccinated, described it as a policy recommendation he had not favored, and called it an error in judgment (NewsNation 2026). He said he has seen no data establishing a link between the vaccine and miscarriage. His objection was to the risk-benefit reasoning and, more sharply, to the absence of the open discussion that would have let women decide for themselves.

Redfield’s current positions on mRNA vaccines contradict the account that academic public health and the obstetric professional societies still promote, and that CDC and FDA officials promoted through 2024. Critics will use that to set him aside. What he said about the January 2021 posture is consistent with the guidance in force when he left.

Just as importantly, Redfield did not claim that the vaccines had been shown to cause miscarriage. He said he had seen no data establishing such a link.

His objection was different, and more fundamental.

The evidence was inadequate to justify replacing individual risk-benefit judgment with a universal recommendation, and the uncertainties should have been discussed openly with the women being asked to make that decision.

Redfield’s current views on mRNA vaccines diverge sharply from those still advanced by much of academic public health and the obstetric professional societies, and from positions maintained by CDC and FDA officials through 2024. That makes it easy for critics to dismiss his 2026 comments as retrospective dissent.

But there is a contemporaneous record against which his claim can be tested.

When Redfield left CDC on January 20, 2021, the agency he had been running did not recommend COVID vaccination for all pregnant women. It explicitly left the decision to them.

Five days later, Fauci privately raised the theoretical possibility of first-trimester miscarriage.

Seven months later, CDC recommended vaccination for every pregnant woman.

What the record supports

No one concealed a known harm.

The mechanism Fauci raised has not been borne out as a miscarriage signal, and the large studies that followed have not found an overall increase in miscarriage after COVID-19 vaccination. That matters, and any honest account of this episode has to say so.

But it does not dispose of what the documentary record shows.

Three of the most influential officials shaping the federal COVID response privately acknowledged that pregnancy data were inadequate. Fauci raised a specific theoretical concern about first-trimester miscarriage following the inflammatory response to vaccination, particularly after the second dose. Walensky immediately recognized the point.

That specific concern was not communicated to pregnant women.

The reassurance offered in the months that followed initially rested in part on a miscarriage calculation that the agency’s own authors later acknowledged used an inappropriate denominator. The corrected analysis was considerably more reassuring, and its central finding has subsequently held. But CDC announced its affirmative recommendation four weeks before that analysis was published and therefore before independent scientists could examine it.

And the headline went considerably further than the evidence beneath it.

“New CDC Data: COVID-19 Vaccination Safe for Pregnant People.”

The new data addressed one outcome, miscarriage before 20 weeks, in a voluntary surveillance registry heavily composed of health care personnel. It did not establish the absence of every potential pregnancy risk, nor could a cohort of that size exclude a risk concentrated in a small susceptible subgroup.

Yet a limited and reassuring finding about one outcome became a categorical statement about safety in pregnancy.

In fact, there have been very limited studies since then.

The studies that were supposed to fill the evidentiary hole did not entirely fill it. Pfizer eventually completed a randomized pregnancy trial, but with 683 participants rather than the thousands originally planned, and vaccination began at 24 to 34 weeks, too late to test the first-trimester miscarriage concern Fauci had raised privately.

Moderna's prospective pregnancy registry was supposed to enroll approximately 600 women. It enrolled twenty and was terminated for low enrollment. By then, of course, the policy decision had long since been made.

Again, no data…

It is unclear whether ACIP ever actually voted to recommend COVID-19 vaccination specifically for pregnant women in 2021. No corresponding 2021 Morbidity and Mortality Weekly Report recommendation has been identified, and the pregnancy guidance instead appears in CDC’s Interim Clinical Considerations, a staff document that changed repeatedly over time.

An inquiry is now with CDC, and the agency has said it is looking into the question.

The answer matters.

If ACIP did vote on the pregnancy recommendation, the record should be straightforward to produce: the meeting, the motion, the vote, the evidence presented, the conflicts disclosed, and the resulting recommendation.

If it did not, then CDC appears to have moved from individual choice to a universal recommendation for a population excluded from the pivotal trials without a specific vote of the independent advisory committee normally expected to publicly examine vaccine recommendations.

That would mean the most consequential change in pregnancy vaccine policy during the pandemic occurred without the public deliberation, recorded vote, conflict disclosures, and recusal procedures that the advisory process is designed to provide.

Redfield identified the deeper failure correctly.

Government scientists will discuss uncertainties privately. They should. Medicine advances because scientists argue about mechanisms, challenge assumptions, worry about signals, and ask questions for which they do not yet have answers.

The ethical failure is not that Fauci had doubts. The ethical failure is that pregnant women were not permitted to share fully in those doubts while being asked to bear the consequences of the decision.

They were entitled to know that the pregnancy data were limited. They were entitled to know what was reassuring. They were entitled to know what remained unknown. And they were entitled to know that the government’s own senior scientists had discussed a theoretical risk that had not yet been resolved.

That is informed consent.

It does not require government scientists to know every answer.

It requires them to tell patients when they do not.

RWM/JGM

References

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