It was a late-spring House of Representatives hearing, where members of Congress and attendees hoped to learn lessons from the pandemic. Witness Marty Makary made a plea.

"I want to thank you for your attempts at civility," Makary, a Johns Hopkins Medicine researcher and surgeon, said softly. Then his tone changed. His voice started to rise, blasting the "intellectual dishonesty" and "very bizarre" decisions of public health officials. Much later, he criticized the "cult" of his critics, some of whom "clap like seals" when certain studies are published. Some critics are "public health oligarchs," he said.

Makary was a marquee witness for this meeting of the Select Subcommittee on the Coronavirus Pandemic. His testimony had the rhythm of a two-step — alternating between an extended hand and a harsh rhetorical slap. It's a characteristic move of this panel, a Republican-led effort to review the response to the pandemic. Both sides of the aisle join in the dance, as members claim to seek cooperation and productive discussions before attacking their preferred coronavirus villains.

One target of the subcommittee's Republican members has drawn concern from public health experts: covid-19 vaccines. Because the attacks range from subtle to overt, there's a fear all vaccines could end up as collateral damage.

During that May 11 hearing, Republican members repeatedly raised questions about coronavirus vaccines. Right-wing star Rep. Marjorie Taylor Greene (R-Ga.) emphasized the vaccines were "experimental" and fellow Georgia Republican Rep. Rich McCormick, an emergency room physician, argued the government was "pushing" FDA-approved boosters "with no evidence and possible real harm."

Some Republican members, who have been investigating for months various pandemic-related matters, are keen to say they're supportive of vaccines — just not many of the policies surrounding covid vaccines. Rep. Brad Wenstrup (R-Ohio), who chairs the subcommittee, has said he supports vaccines and claimed he's worried about declining vaccination rates.

During the May hearing, he also two-stepped, arguing the covid shots were "safe as we know it, to a certain point." He questioned the government's safety apparatus, including VAERS, the Vaccine Adverse Event Reporting System, a database that receives reports potentially connected to vaccines. He said the committee would be "looking" at it "to make sure it's honest and to be trusted."

It's this two-step — at once proclaiming oneself in favor of vaccines, while validating concerns of vaccine-skeptical audiences — that has sparked worries of deeper vaccine hesitancy taking root.

"It seems to me to be implying the government knows the vaccine to be unsafe" and that it's "covering it up," said Matt Motta, a political scientist at Boston University specializing in public health and vaccine politics. The implication validates some long-held fringe theories about vaccinations, without completely embracing "conspiracism," he said.

Vaccine skeptics run the gamut from individuals with scientific credentials who nevertheless oppose public health policies from a libertarian perspective to individuals endorsing theories about widespread adverse events, or arguing against the need for multiple shots. VAERS is a favorite topic among the latter group. When one witness testifying during the May 11 hearing attempted to defend covid vaccination policies, Taylor Greene cited the number of reports to VAERS as evidence of the vaccines' lack of safety.

That muddles the purpose of the database, Motta said, which gathers unverified and verified reports alike. It's a signal, not a diagnosis. "It's more like a smoke alarm," he said. "It goes off when there's a fire. But it also goes off when you've left an omelet on the stove too long."

In a March hearing focusing on school reopening policies, Democratic members of the panel and a witness from a school nurses association frequently touted the important role covid vaccines played in enabling schools to reopen. Wenstrup offered generalized skepticism. "I heard we were able to get more vaccines for the children," he said. "We didn’t know fully if they needed it. A lot of data would show they don’t need to vaccinate."

Witnesses can eagerly play into vaccine-skeptical narratives. After a question from Taylor Greene premised on the idea that the covid vaccines "are not vaccines at all," and alleging the government is spreading misinformation about their effectiveness, Makary suggested that while he was not anti-vaccine, it was understandable others were. "I understand why they are angry," he said, in response. "They've been lied to," he said, before criticizing evidence standards for the newest covid boosters, tailored to combat emerging variants.

The signals aren't lost on audiences. The subcommittee has, like most congressional panels, posted important moments from its hearings to Twitter. Anti-vaccine activists and other public health skeptics reply frequently.

"It’s hard for me to think of a historical analogue for this — it’s not often that we have a Congressional committee producing content that has its fingers on the pulse of the anti-vaccine community," Motta wrote in an e-mail, after reviewing many of the subcommittee's tweets. "The committee isn’t expressly endorsing anti-vaccine positions, beyond opposition to vaccine mandates; but I think it’s quite possible that anti-vaccine activists take this information and run with it."

Motta's concern is echoed by the panel's Democratic members. "I pray this hearing does not add to vaccine hesitancy," said Rep. Kweisi Mfume (D-Md.), who represents Baltimore.

One witness reiterated that point. Many members “have a lot of skepticism about vaccines and were not afraid to express that,” Tina Tan, a specialist in pediatric infectious diseases at Northwestern University, told KFF Health News. She testified at the hearing on behalf of the minority.

Polling is showing a substantial — and politically driven — level of vaccine skepticism that reaches beyond covid. A slim minority of the country is up to date on vaccinations against the coronavirus, including the bivalent booster. And the share of kindergartners receiving the usual round of required vaccines — the measles, mumps, and rubella, or MMR, inoculation; tetanus; and chickenpox among them — dropped in the 2021-22 school year, according to the Centers for Disease Control and Prevention. Support for leaving vaccination choices to parents, not as school requirements, has risen by 12 percentage points since just before the pandemic, mostly due to a drop among Republicans, according to a recent poll by the Pew Research Center.

And vaccine skepticism is resonating beyond the halls of Congress. Some state governments are considering measures to roll back vaccine mandates for children. As part of a May 18 procedural opinion, Supreme Court Justice Neil Gorsuch cited two vaccination mandates — one in the workplace, and one for service members — and wrote that Americans "may have experienced the greatest intrusions on civil liberties in the peacetime history of this country." He made this assertion even though American military personnel have routinely been required to get shots for a host of diseases.

"We can't get to a spot where we're implicitly or explicitly sowing distrust of vaccines," cautioned California Rep. Raul Ruiz, the Democratic ranking member of the coronavirus subcommittee.

This article was reprinted from khn.org with permission from the Henry J. Kaiser Family Foundation. Kaiser Health News, an editorially independent news service, is a program of the Kaiser Family Foundation, a nonpartisan health care policy research organization unaffiliated with Kaiser Permanente.