Experts say Robert F. Kennedy Jr., Secretary of Health and Human Services.

According to a HHS spokesman, under Kennedy’s change, all new vaccines require placebo-controlled clinical trials (some get actual shots, while others get inactive stuff, such as saline shots, to compare results.

For most new vaccines, running trials that include the placebo group are already routine.

The initial Covid vaccine from Pfizer and Hyundai was approved in late 2020 and passed a placebo-controlled trial. But as the virus continues to mutate, vaccines need to be updated to match circulating strains, pharmaceuticals moved to influenza-like vaccine-like models – using smaller studies to test how updated lenses trigger immune responses to the variants in question.

Like the annual flu vaccine, the updated COVID vaccine is not considered a brand new product, as they still use the same formula, simply adjusting the target vector of the vaccine. An mRNA covid vaccine was designed so that such changes were particularly easy to make when a rapid update was required.

In this case, it was quickly proven to be several months. To prepare for enough doses to fall, vaccine manufacturers are told in the spring which strains to target.

The Food and Drug Administration’s Vaccine Advisory Committee is expected to meet in May or June to recommend that strains should be included in the next round of shooting. A person familiar with the matter has no right to speak out publicly, saying the FDA plans to schedule a May 22 meeting. A HHS spokesperson declined to comment on the meeting date.

Experts say that if the FDA believes that "new" products of Pfizer and Hyundai require new trials, the dose cannot be prepared for the fall.

The change will almost certainly delay "months" of Pfizer and Hyundai's updated lenses as it will take time to design new trials and participants, said Dr. Paul Offit, director of the Center for Vaccine Education in Children's Hospital in Philadelphia and a member of the FDA's Vaccine Advisory Committee.

That will just start - then the drugmaker will have to conduct actual trials, which will take at least a few months and analyze the results.

Even the "most successful government science program" is known as the "most successful government science program" even as it is known as the "most successful government science program."

A HHS spokesman did not directly answer questions about whether Pfizer and Moderna vaccines require new clinical trials.

However, the spokesperson said in a statement: "FDA Commissioner Dr. Marty Makary noted that significant updates to existing vaccines, such as those that address seasonal strain changes or antigen drift, may be viewed as "new products" that require additional clinical evaluation."

"As we said before, four years ago trials have been tried for people without natural immunity," the spokesman said. "One year trial is not a blank check for new vaccines without clinical trial data every year." They added that the flu vaccine will not be exempted from the new rules because it "has been over 80 years of review and testing."

The FDA has postponed approval of Novavax's updated Covid vaccine, requiring the company to conduct new clinical trials as the pressure in SHOT differs from the initial authorization differences.

Vaccine experts have made new demands.

Offit said it was “immoral”, noting that when there was already an approved product that could protect them, the scientific community often frowned a placebo.

Pediatrician Dr. Stanley Plotkin, who played a key role in developing a rubella vaccine, said the move “does not make sense.”

"What's reasonable is to compare the old vaccines to the new ones to see if the new vaccines provide a better immune response," Plotkin said. "We have vaccines for Covid, where we have fairly specific ideas about what works and doesn't work. We know they're not perfect, but we know vaccines that work."

A spokesperson for Pfizer and Moderna did not immediately respond to a request for comment.

Former administration officials said HHS, under Kennedy, is taking approval of a slow-walking vaccine, including imposing new regulatory barriers to drugmakers, such as changing approval requirements or seeking other clinical trial data.

Vaccine experts also worry that rule changes are part of Kennedy’s broader effort to sow vaccines distrust and limit public use.

"The goal is to make the vaccine more cumbersome, and test it by asking these wrong safety issues or false effectiveness issues," Offit said.

Dr. Sean O'Leary, chairman of the American Council on Pediatric Diseases, said the change is unlikely to affect a brand new vaccine. However, due to the expensive placebo trials, more time is required, which may have a significant impact on the vaccines that may require renewal (such as RSV).

"It's really not feasible and it will lead to many hospitalizations and deaths," O'Leary said.

Plotkin added that vaccines developed for incurable infections like HIV may also be at risk.

"Suppose you want to develop a new HIV vaccine?" he asked. "Will you do a placebo-controlled trial in this case? I mean putting a child in a very serious illness without providing anything."