Internal memos that recently surfaced as part of a lawsuit against the U.S. Department of Health and Human Services (HHS) reveal that the decision to rescind Covid-19 vaccine recommendations for pregnant individuals and children was based on limited data.

Critics argue that these memos ignored numerous studies demonstrating the safety and benefits of Covid-19 vaccinations. They warn that this move could set a concerning precedent where changes to vaccine recommendations are driven more by ideology than by scientific evidence.

As U.S. health officials consider significant alterations to immunization guidelines, members of the Advisory Committee on Immunization Practices (ACIP) have indicated they are examining the issue of vaccines during pregnancy. The committee, which includes several members known for their anti-vaccine positions, is scheduled to convene on Wednesday and Thursday. Recently, they reportedly abandoned plans to discontinue recommendations for all mRNA-based Covid-19 vaccines.

On May 27, Robert F. Kennedy Jr., a longtime vaccine critic and current HHS secretary, announced a notable shift in Covid-19 vaccine recommendations via a post on X. This announcement marked the beginning of a series of substantial changes to the U.S. health leaders’ stance on routine immunizations, stating that vaccines would no longer be advised for “healthy” children and pregnant individuals.

Two memos, both dated May 12, which discuss vaccination during pregnancy and childhood, were circulated within U.S. health agencies prior to the decision. These documents have now been disclosed as part of the lawsuit filed by the American Academy of Pediatrics (AAP) against the current administration.

Kevin Ault, an obstetrician and gynecologist who previously contributed as an expert to ACIP working groups, expressed surprise at the contents of these memos. He criticized the officials for overlooking the vast majority of relevant data in their analysis. Ault described the process of independently assembling an evidence base and making decisions via internal memos as “highly unusual.”

Naima Joseph, a maternal fetal medicine specialist at Boston Medical Center who served on the ACIP working group for the Covid vaccine, said: “The citations were not evidence-based, but more like biased perspectives.” Taking away the recommendations is “not aligned with international recommendations, such as the WHO”, she added, and the move put the US out of step with other nations.

Tracy Beth Høeg, who was at the time the senior adviser for clinical sciences to Marty Makary, commissioner of the US Food and Drug Administration (FDA), wrote a short memo with only 12 citations, including two of her own studies, on Covid vaccines in pregnancy. She pointed out that the initial randomized clinical trials from “Pfizer, Modern [sic] and Novavax excluded pregnant women”, but did not note that some people became pregnant during the trials and showed no adverse side effects – and at least 258 studies have since shown the safety and effectiveness of Covid vaccination in pregnancy.

The evidence on Covid vaccination was “misconstrued” and “distorted”, Joseph said. Data from the US Centers for Disease Control and Prevention (CDC) shows no increased risk of short- or long-term complications from vaccination, she said: “The data are so reassuring, and it’s really, at this point, a very well-studied vaccine in pregnancy.”

The risk of Covid infection, conversely, remains a big concern. Covid infects the placenta, which can lead to poor intrauterine growth, prematurity, stillbirth and other complications. Compared with unvaccinated individuals, people who receive Covid vaccines in pregnancy have a lower risk of complications, keeping recipients out of the hospital and the intensive care unit and preventing pre-term delivery.

Even after years of immunity acquired by infection, “we’re still seeing data to support that vaccination helps,” Joseph said. Ending the recommendation “puts pregnant women and their infants at higher risk for complications that are preventable”, she said.

There are benefits to vaccination in pregnancy that extend far beyond birth. Babies under the age of six months cannot get vaccinated against Covid, and they have one of the highest rates of hospitalization for the virus. Vaccination in pregnancy can help protect them against serious illness. There is also some evidence that forgoing vaccines in pregnancy may lead to delayed or skipped vaccination for babies. “It gets the whole process off to a poor start – if there’s confusion about maternal vaccines, that can bleed over into the first year or two of vaccines for the newborn,” Ault said.

Officials in May also took aim at Covid vaccines for children. A memo from Matt Memoli, principal deputy director at the National Institutes of Health (NIH), and Sara Brenner, principal deputy commissioner of the FDA, said that there was “no clear evidence” that the benefits of Covid vaccination “outweigh the risk of harm in children under 18 years of age” – but they cited at least one study that concluded Covid deaths in children had fallen significantly in part because of vaccination. Other studies, not mentioned by the officials, show Covid vaccination in childhood helps reduce long-term symptoms, complications like myocarditis and hospitalization.

The HHS did not respond by press time to questions about claims made in the memos and the role they played in restricting vaccines.

Members of ACIP said they had created a working group for vaccination in pregnancy in December. Previously, every working group already included obstetricians and gynecologists as outside experts, but they were excluded from the discussions under Kennedy. After being excluded, the AAP left the meetings, and the American College of Obstetricians and Gynecologists (ACOG) recently announced it would no longer participate as well.