New US vaccine strategy against monkeypox could be a huge boost to supply, but much is unknown

Still, the specific efficacy data for the vaccine is not clear, and some experts argue that not enough is known about how the low-dose intradermal strategy might affect the protection it provides in the real world.

Even at the original dosage, “there is no traditional review of this vaccine,” said Dr. Robert Califf, commissioner of the US Food and Drug Administration, Tuesday. It’s approved for emergencies based on immune response studies, not clinical results, because there have been no outbreaks of smallpox or monkeypox large enough to test it.

The intradermal route “may increase the number of doses available in an emergency situation,” according to the study’s findings. Last week, the United States declared monkeypox a national public health emergency.

US officials said Tuesday there are plans to collect real data on the vaccine and the National Institutes of Health will begin a clinical trial.

The new federal strategy still requires two doses of the vaccine 28 days apart, and it says people who get their first dose subcutaneously can get their second dose intradermally or subcutaneously.

But some people are concerned about the shift to a low-dose intradermal strategy.

“While we appreciate that the federal government is finally willing to seek solutions to address the vaccine shortage, no effort to protect people’s health should come without due diligence and research,” David Harvey, executive director of the National Coalition of STD, the director said in a statement on Tuesday.

“We are very concerned about the limited amount of research that has been done on this dose and delivery method, and we fear it will give people a false sense of confidence that they are protected. This approach is raising red flag after red flag and seems to move forward urgently without data on efficacy, safety or alternative dosing strategies.”

The Chicago Department of Public Health said Wednesday it will go along with the federal plan to expand the supply of monkeypox vaccine by moving to smaller doses given in a different way — but it won’t happen overnight. to happen.

“I think it will be a few weeks before we roll out more widely,” said Dr. Allison Arwady, commissioner of the Chicago Department of Public Health.

Other city health departments, such as Columbus Public Health in Ohio, are still reviewing the new federal strategy and what it means for their local response.

“Because this guideline is new, we are currently reviewing it to determine the impact on our vaccine effort, staffing and supplies,” Kelli Newman, a spokesperson for Columbus Public Health, wrote in an email to CNN on Wednesday.

A need for ‘formal clinical efficacy data’

The efficacy of Jynneos for the prevention of monkeypox was originally tested in animals exposed to the virus and can be inferred from antibody responses seen in humans participating in smallpox clinical trials.

But the Jynneos vaccine was originally developed to help defend the country against smallpox as a response to bioterrorism — so there’s still not much data on exactly how well it protects against monkeypox infection, even with a subcutaneous dose.

“There is no formal clinical efficacy data with the monkeypox vaccine — but that’s not a criticism of the vaccine. In fact, I think it’s a testament to the vaccine development efforts that we actually already have a monkeypox vaccine, largely before this major outbreak,” said Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston.

The FDA approved the Jynneos vaccine in 2019 to prevent smallpox and monkeypox, but the approval was mainly to offer a smallpox vaccine option that does not contain a live virus. Before that, Sanofi Pasteur Biologics’ ACAM2000 was the only FDA-approved vaccine for the prevention of smallpox. Jynneos is the vaccine of choice in the current outbreak because ACAM2000 may have more side effects and is not recommended for people with severely weakened immune systems.

“Jynneos was a second-generation smallpox vaccine whose use was a backup vaccine for individuals unable to receive ACAM2000 in the event of a biological smallpox weapon attack,” said Dr. Amesh Adalja, a senior scientist at the Johns Hopkins Center for Health Security at the Johns Hopkins Bloomberg School of Public Health.

“It was not my intention to use ACAM2000 or Jynneos for monkeypox,” he said. “While they were effective against it, it wasn’t considered something they were developing it for.”

When Jynneos was approved, FDA officials said its effectiveness for the prevention of smallpox was determined by a clinical study of about 400 healthy adults. Half of them got ACAM2000 and the other half Jynneos.

The U.S. Centers for Disease Control and Prevention estimate that: the Jynneos and ACAM2000 smallpox vaccines are at least 85% effective in preventing monkeypox.
Should I be concerned about monkey pox now?  Our medical analyst explains:

“While we have no clinical efficacy data, it is likely that Jynneos will be very effective, because of what we know about the smallpox vaccine and because of the efficacy with Jynneos against monkeypox in animals,” Barouch said.

He added that “vaccines are generally more effective at preventing the serious consequences of the disease than preventing infection with the pathogen.”

“We can be confident that this will likely be a very effective vaccine, but the details of it in terms of its exact numerical efficacy — and whether that will be prevention of infection or prevention of serious disease — those details are really unknown at this point.” said Barouch. “I do think that people at high risk should be vaccinated, but at the moment I don’t think it’s possible to give very precise guidelines on what that protection will look like.”

An opportunity to ‘significantly improve’ availability

The uncertainties surrounding the effectiveness of the Jynneos vaccine will be exacerbated by the change to a lower dose of the vaccine in the real world, outside of a clinical trial, Dr. Philip Krause, former deputy director of the FDA’s Office of Vaccines Research and Review, and infectious disease physician Dr. Luciana Borio wrote in Stat News on Tuesday.

“If the vaccine can be administered at lower doses without risking effectiveness, lower dose intradermal injections make sense,” Krause and Borio wrote. “But this strategy could also backfire. If there’s a risk to effectiveness, it might be better to focus available full doses of vaccine on those at the highest risk — men who have sex with multiple male partners — to get the best chance.” to get the outbreak under control.”

The initial strategy to vaccinate only known monkeypox contacts was "doomed to failure"  in the US, experts say:

During the outbreak, the vaccine has been given to health professionals treating people with monkeypox, to close patient contacts and to people who have been able to find doses at local clinics. The CDC estimates that at least 1.5 million people in the US are eligible for monkey pox vaccination.

“We have a line around the corner,” said Dr. Stacy Lane, a clinician at the Central Outreach Wellness Center in Pittsburgh, spoke Tuesday about the monkeypox vaccine demand at her clinic.

The United States Department of Health and Human Services has provided more than 670,000 doses of Jynneos vaccine from the Strategic National Stockpile to support local monkeypox control efforts on the ground.

In addition, the SNS is preparing to distribute approximately 400,000 additional vials to states and jurisdictions as part of the next phase of the national vaccine strategy, the White House said. “Jurisdictions that administer 90% of their current vaccine stock may be able to request additional doses sooner.”

And because of the authorization of intradermal injections, “the 400,000 vials of vaccine in the SNS’s inventory that have been allocated but not yet distributed have the potential to deliver up to 2 million doses using intradermal administration. In addition, vaccines approved by jurisdictions have received, but not yet administered, are eligible for intradermal administration.”

Lane said the shift to an intradermal strategy could “significantly improve vaccine availability.” Her clinic has ordered the shorter syringes needed to administer the vaccine intradermally, the same ones used for tuberculosis testing, she said.

“I ordered it this afternoon,” she said Tuesday, before the FDA gave her approval.

Lane said many of her patients are concerned about getting monkeypox, and she refers them to the ACAM2000 vaccine data as a reference point for how well the Jynneos vaccine can protect against monkeypox.

“What we’re informing people about is that we know from historical data that the ACAM2000 vaccine that was historically given in Africa provided about 85% protection against monkeypox. We know that these orthopox families of viruses tend to respond to the same treatment.” , as well as that the vaccine is somewhat effective,” Lane said.

She added that she does not anticipate any concerns about the new vaccination strategy.

“We don’t really see any hesitation about vaccines, at least right now,” she said.

dr. Paulette Gray Riveria agreed that the intradermal strategy could be an effective way to stretch the stock.

“Given that less vaccine volume is required for an intradermal versus a subcutaneous dose, intradermal Jynneos injections may be a reasonable option to maximize delivery without compromising vaccine protection,” Gray Riveria, family medicine physician with the virtual health platform PlushCare, and a regional medical director for the state of Louisiana, wrote in an email to CNN.

“Scientists are actively investigating whether immune cells under the skin can activate an antibody response with equal or greater efficiency compared to the subcutaneous route.”

CNN’s Jen Christensen contributed to this report.

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