Officials struggle to decide whether to allow a new monkeypox vaccination strategy

WASHINGTON – It seemed like a simple solution to the monkeypox vaccine shortage: simply by changing the way the doses are injected, the federal government could vaccinate five times more people with the supply it holds.

But the approach – injecting a fifth of the current dose into the skin instead of a full dose into the underlying fat – isn’t actually that simple, experts say. And some federal officials are concerned about changing the method without further research, though Dr. Robert M. Califf, the head of the Food and Drug Administration, on Thursday described the proposal as promising.

Some outside experts are also urgently cautious. “From a basic scientific standpoint, this should work,” said Dr. Jay K. Varma, director of the Cornell Center for Pandemic Prevention and Response. “But obviously, there are a lot of things in life, in science, that we think should work, and then when we actually do them, they don’t.”

Extending the doses of the vaccine, Jynneos, could help the federal government resolve a situation partly of its own making. Although it has invested more than $ 1 billion in developing the two-dose vaccine for use against both monkeypox and smallpox, the government only has 1.1 million vaccinations on hand, in part because it has been slow in ordering bulk vaccine stocks to be turned into vials.

That supply is enough to cover 550,000 people, but roughly triple the doses are needed to cover the 1.6 million and 1.7 million Americans who, according to the Centers for Disease Control and Prevention, are at high risk of monkeypox. . For now, the virus has mainly spread through skin-to-skin contact during sex between gay and bisexual men, the CDC said.

Some federal officials hope that by injecting a smaller dose of the vaccine between the layers of the skin, called an intradermal injection, the Biden administration can quell the outbreak before it spreads more widely.

But some experts argue that this approach has not been sufficiently studied. They also warn that some vaccinators will need training to properly deliver shots, which could slow vaccination efforts. Otherwise, the government could end up wasting doses, not saving them.

Intradermal injection consists of carefully guiding a needle into the layers of the skin, a thin space with immune cells. If a vaccinator goes too deep and inserts the dose into the fat, the patient may not get enough vaccine, experts say. But if the needle is not inserted far enough, some of the vaccine may leak.

“If you are giving a lower dose and you are not injecting it properly into the skin – you may be injecting it in the wrong place – you may not be giving a protective vaccine,” said Dr. Phil Krause, who last year stepped down as the FDA’s vaccine regulator and worked on licensing the Jynneos agency. “If you ask for this to be done nationwide in millions of doses, mistakes are much more likely to be made in vaccine administration.”

On the other hand, the method has a track record. It has been used in polio vaccination campaigns when doses have been limited, as well as for rabies and tuberculosis skin tests.

“It’s not a brand new concept,” said Dr. Anthony S. Fauci, President Biden’s chief medical adviser. “We were thinking of this as a vaccine shortage strategy years ago.”

Vaccinators used special bifurcated needles in smallpox inoculation campaigns which allowed them to perform intradermal injections more evenly and economically.

Dr John Beigel, an associate director of clinical research at the National Institutes of Health, said a government-sponsored study of Jynneos published in 2015 compared the intradermal approach to the standard injection method and found that it activated a level comparable to neutralizing antibodies, a measure of the strength of the immune response. The intradermal method caused more redness, swelling, and itching, but the standard injection was more painful.

Dr Beigel said switching to the intradermal method was a better option for preserving the vaccine than administering a single shot, as some jurisdictions are doing now, because research has shown that a shot is not as strong as an immune response. .

“One dose is likely not effective,” he said, adding that the intradermal method “is an acceptable way to go.”

Although the 2015 study involved hundreds of participants, some experts note that it was a single study limited in what it measured. The NIH researchers had planned to test the intradermal strategy for Jynneos in a process that was due to begin in a few weeks. But results weren’t expected until late fall or early winter, and that plan is in the air for now.

Dr H. Clifford Lane, the clinical director of Dr. Fauci’s National Institute of Allergy and Infectious Diseases at the NIH, said that while researchers could glean information from tracking people who are vaccinated, a traditional clinical trial would provide a framework clearer.

“I can understand doing it as long as it’s very clear why it’s done,” he said of the intradermal strategy. “The question is, how can we extend current supplies without significantly compromising effectiveness?”

Another question is how well the vaccine will actually work – it was licensed in 2019 for use against both monkeypox and smallpox after studies showed it provoked a stronger immune response than a previous vaccine. That drug itself was approved because it compared to an even earlier vaccine, federal officials said.

Monkeypox is rarely fatal, and no deaths have been reported in the United States. Symptoms typically resolve within two to four weeks. But with the outbreak going from eight reported cases in late May to 7,510 now, the administration is rushing to try to improve vaccination rates and the availability of tests and treatments.

As of now, the outbreak is almost entirely limited to men who have sex with men, with those having multiple partners considered particularly at risk. But five cases involving children have been reported so far. On Friday, the Illinois Department of Public Health announced that an adult working at a day care center had tested positive for monkeypox and that children and other staff had been screened.

Thursday’s health emergency statement allowed the federal government to expedite monkeypox investigations and approve grants, but did not invoke the FDA’s emergency powers. Changing the injection mode would require a second type of emergency declaration, giving the Food and Drug Administration more leeway to issue emergency use authorizations.

Federal regulatory authorities may issue emergency product authorizations when they believe the potential benefits outweigh the potential risks. At the start of the coronavirus pandemic, the Trump administration issued the same type of emergency declaration, allowing the FDA to make Covid-19 vaccines available to Americans many months before regulators released full approval.

Dr Califf, the FDA commissioner, said Thursday that regulators will continue to ensure that the vaccine is delivered safely and effectively. He said regulators would likely decide in the next few days whether to adopt the intradermal strategy, but that “it was doing well right now,” a comment some outside experts said seemed to anticipate career regulators’ deliberations.


Emily Cochrane and Tracey Tully contributed to the reporting.